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7mm Creedmoor/GDC (Page 1 of 2)
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Posted: 7/11/2015 12:00:42 AM EDT
[Last Edit: 7/11/2015 10:18:48 AM EDT by steinhab]
It's either a 6.5 Creedmoor necked up to take 7mm, or a 30TC necked down. Way better velocities than 7-08, but fits in the standard SA mags with VLD bullets loaded long. I'm interested in shooting Hornady 162 Amax bullets, with H4350, but not100% on the reloading, as I'm a novice when it comes to that part.

Anyone have any experience or knowledge about this wildcat cartridge? Specifically about names of smiths that do barrels and provide reloading dies? I've heard of Short Action Customs from some old SH posts but not much talk about it recently.

Is it worth going .280 Remington for the simpler reloading?
Link Posted: 7/11/2015 12:10:50 AM EDT
284 seems to be the next big thing.  Its been around but has seen a resurgence in LR shooting.
Link Posted: 7/11/2015 12:14:33 AM EDT
280 gets you a long action and no one wants that. You'd be better off going with a magnum and using AICS magnum magazines.

I'm interested in 7MM Creedmor as well.  Haven't seen much about it lately.
Link Posted: 7/11/2015 10:25:38 AM EDT
I was originally thinking of going with a 7 Wsm or a 7 SAUM but with both you get the lower round counts and much more expensive brass. My goal is to have a good long range shooter that bucks the wind like a champ but won't break the bank to reload and won't need to be rebarrelled often.

After reading about 7 Creedmoor, I'm pretty stoked about it but it seems that resizing brass is a pain in the butt, with the creator of 7 GDC recommending to resize Lapua 308 palma brass, and then fire form it. I've heard complaints that necking up 6.5 Creedmoor brass, which would be the easiest process, creates donuts at the neck.



Link Posted: 7/11/2015 12:29:12 PM EDT
I've seen a LOT of posts on the 6 Creedmoor and would be interested in a 7 Creedmoor.

Donuts are somewhat easily rectified with neck turning. The 162 Amax would be an awesome projectile for this cartridge. Be very interested in what others have to say.
Link Posted: 7/11/2015 12:35:11 PM EDT
[Last Edit: 7/11/2015 12:35:37 PM EDT by steinhab]
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Originally Posted By capreppy:
I've seen a LOT of posts on the 6 Creedmoor and would be interested in a 7 Creedmoor.

Donuts are somewhat easily rectified with neck turning. The 162 Amax would be an awesome projectile for this cartridge. Be very interested in what others have to say.
View Quote


Can you neck turn the inside of the neck, near the shoulder? Because I think that's where the donut forms. Some people have said that because of the Amax's shape and that it is usually loaded long, the donuts don't even matter.



Link Posted: 7/11/2015 3:57:52 PM EDT
[Last Edit: 7/11/2015 3:59:00 PM EDT by mathecb]
Originally Posted By steinhab:
Way better velocities than 7-08
View Quote


How much more velocity are we talking over the 7mm-08 assuming both are being handloaded?
Link Posted: 7/11/2015 10:09:00 PM EDT
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Originally Posted By mathecb:


How much more velocity are we talking over the 7mm-08 assuming both are being handloaded?
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Originally Posted By mathecb:
Originally Posted By steinhab:
Way better velocities than 7-08


How much more velocity are we talking over the 7mm-08 assuming both are being handloaded?


Now this is only coming from a quick Google search, but a 7mm-08 with a 24" barrel and a 162 gr Amax will get about 2700-50 fps. A 7mm Creedmoor will get about 2850-2900 out of the same length barrel, with slightly less powder as well (maybe a grain less). This is mainly due to the better shoulder angle of the Creedmoor casing, 30 degrees vs. 20 for the 7-08.

Additionally, and this is just from what I've read and why I'm kind of digging the idea of a wildcat like 7mm Creedmoor, the 6.5 and 7mm Creedmore rounds can be loaded longer with a VLD bullet and still fit mag-length, due to the shorter case, as compared to a 260 or 7mm-08, which both have a bit of trouble fitting mag length in anything but a few types of detachable mag chassis systems, which will fit longer than normal COAL rounds, like the Wyatts DBM. The 6.5 Creedmoor is probably better than the 260, slightly under the 7-08 in ballistics but much easier to load easier. But the 7mm VLD bullets are just so much better than the 6.5 bullets, especially in wind deflection. I live in Texas and I want something that will handle the wind better, so if I made a slightly off wind call, maybe 2-4 mph off what actual conditions are, it wont matter too much unless at a very long range. And using a non-magnum short action, with little recoil, is the tits.  

I'm far from an expert but this basically some of the info I've picked up reading online on various forums. Its not gospel.
Link Posted: 7/11/2015 10:13:04 PM EDT
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Originally Posted By steinhab:


Can you neck turn the inside of the neck, near the shoulder? Because I think that's where the donut forms. Some people have said that because of the Amax's shape and that it is usually loaded long, the donuts don't even matter.

http://www.singleactions.com/images/Neck_Donut.jpg

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Originally Posted By steinhab:
Originally Posted By capreppy:
I've seen a LOT of posts on the 6 Creedmoor and would be interested in a 7 Creedmoor.

Donuts are somewhat easily rectified with neck turning. The 162 Amax would be an awesome projectile for this cartridge. Be very interested in what others have to say.


Can you neck turn the inside of the neck, near the shoulder? Because I think that's where the donut forms. Some people have said that because of the Amax's shape and that it is usually loaded long, the donuts don't even matter.

http://www.singleactions.com/images/Neck_Donut.jpg



Yes, K&M makes a cutting arbor that would easily solve that problem.
Link Posted: 7/11/2015 10:21:43 PM EDT
[Last Edit: 7/11/2015 10:28:31 PM EDT by SuperJlarge]
2850-2900 with a 162? If a 6.5cm with 140's is pushing that, how will a 7mm do that with a heavier bullet and the same or less case capacity

260 VLD's feed ok from AICS mags. The big gripe is they don't work as well in the AR-10 style mags.
Link Posted: 7/11/2015 10:52:06 PM EDT
I am not understanding how it is picking up speed with a heavier bullet either. Seems like a unicorn.
Link Posted: 7/11/2015 10:54:34 PM EDT
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Originally Posted By capreppy:


Yes, K&M makes a cutting arbor that would easily solve that problem.
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Originally Posted By capreppy:
Originally Posted By steinhab:
Originally Posted By capreppy:
I've seen a LOT of posts on the 6 Creedmoor and would be interested in a 7 Creedmoor.

Donuts are somewhat easily rectified with neck turning. The 162 Amax would be an awesome projectile for this cartridge. Be very interested in what others have to say.


Can you neck turn the inside of the neck, near the shoulder? Because I think that's where the donut forms. Some people have said that because of the Amax's shape and that it is usually loaded long, the donuts don't even matter.

http://www.singleactions.com/images/Neck_Donut.jpg



Yes, K&M makes a cutting arbor that would easily solve that problem.


Do you have a link to it? I'd like to look into it.
Link Posted: 7/11/2015 11:06:46 PM EDT
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Originally Posted By SuperJlarge:
2850-2900 with a 162? If a 6.5cm with 140's is pushing that, how will a 7mm do that with a heavier bullet and the same or less case capacity

260 VLD's feed ok from AICS mags. The big gripe is they don't work as well in the AR-10 style mags.
View Quote


For 6.5 Creedmore, I found this thread:

"While reloaders will indubitably try to hotrod the cartridge, factory ammunition is limited to 58,000 psi and shoots the 140-gr A-MAX (BC 0.585) at 2810 fps from a 26-inch barrel. ...
The recipe for the 140-grain A-MAX load is 41.7 grains of H4350 with a Federal 210 Match primer loaded to 2.820 inches; my reloads shot to within 10 fps of the factory-loaded ammunition"

For 7mm Creedmore, In this snipers hide thread, a poster states this:

"The low velocity was 2869 fps and the high 2875 fps. That's with 41gr of XBR, 162gr A-Max and 210M primers"

The 7mm load is using XBR, which burns much faster than H4350 (the preferred 6.5 creedmoor barrel). With H4350 shooters are reporting only 2650 or so with the 7mm Creedmoor. So the 7mm load might be a high pressure hotter load or at least it moves better with XBR, which is quite like Varget, a quick burning powder and very temperature stable.
Link Posted: 7/11/2015 11:15:34 PM EDT
I think it would be cool to neck up and 6.5 creedmoor to a 30 cal. Oh Wait, Nevermind.
Link Posted: 7/11/2015 11:28:53 PM EDT
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Originally Posted By Bluegrasshopper:
I think it would be cool to neck up and 6.5 creedmoor to a 30 cal. Oh Wait, Nevermind.
View Quote


It would be the original case, a 30TC. Why would you bother though? No .30 cal bullet can compare in external ballistics until you surpass 210 grains, which wouldn't work for shit in anything under a 300 Winmag (too slow).

The more I look into it, the more I realize that 30 cal sucks in anything short of a winmag shooting huge bullets.
Link Posted: 7/12/2015 9:39:55 AM EDT
I was just curious because the 6.5 Creed and .260 are roughly the same as far as velocity goes. The Creed does have a steeper shoulder angle but also has a shorter case. I would like to see a comparison between the two with same length barrels. When I shot a .260 I could get 2875 with the 140's from a 26" tube. It gave up nothing to the 6.5 Creed.
Link Posted: 7/12/2015 12:16:51 PM EDT
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Originally Posted By steinhab:


For 6.5 Creedmore, I found this thread:

"While reloaders will indubitably try to hotrod the cartridge, factory ammunition is limited to 58,000 psi and shoots the 140-gr A-MAX (BC 0.585) at 2810 fps from a 26-inch barrel. ...
The recipe for the 140-grain A-MAX load is 41.7 grains of H4350 with a Federal 210 Match primer loaded to 2.820 inches; my reloads shot to within 10 fps of the factory-loaded ammunition"

For 7mm Creedmore, In this snipers hide thread, a poster states this:

"The low velocity was 2869 fps and the high 2875 fps. That's with 41gr of XBR, 162gr A-Max and 210M primers"

The 7mm load is using XBR, which burns much faster than H4350 (the preferred 6.5 creedmoor barrel). With H4350 shooters are reporting only 2650 or so with the 7mm Creedmoor. So the 7mm load might be a high pressure hotter load or at least it moves better with XBR, which is quite like Varget, a quick burning powder and very temperature stable.
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Originally Posted By steinhab:
Originally Posted By SuperJlarge:
2850-2900 with a 162? If a 6.5cm with 140's is pushing that, how will a 7mm do that with a heavier bullet and the same or less case capacity

260 VLD's feed ok from AICS mags. The big gripe is they don't work as well in the AR-10 style mags.


For 6.5 Creedmore, I found this thread:

"While reloaders will indubitably try to hotrod the cartridge, factory ammunition is limited to 58,000 psi and shoots the 140-gr A-MAX (BC 0.585) at 2810 fps from a 26-inch barrel. ...
The recipe for the 140-grain A-MAX load is 41.7 grains of H4350 with a Federal 210 Match primer loaded to 2.820 inches; my reloads shot to within 10 fps of the factory-loaded ammunition"

For 7mm Creedmore, In this snipers hide thread, a poster states this:

"The low velocity was 2869 fps and the high 2875 fps. That's with 41gr of XBR, 162gr A-Max and 210M primers"

The 7mm load is using XBR, which burns much faster than H4350 (the preferred 6.5 creedmoor barrel). With H4350 shooters are reporting only 2650 or so with the 7mm Creedmoor. So the 7mm load might be a high pressure hotter load or at least it moves better with XBR, which is quite like Varget, a quick burning powder and very temperature stable.


No doubt that you can get faster velocities by changing to powders of different burn rates, but even that poster stated that it was hot! Achieving that velocity and doing it safely are two different things. The other thing to consider is barrel speed and measuring equipment. Another poster stated that he used the same hot load and only achieved 2802fps in a 24.9" barrel. This seems more in line with what I would anticipate without pushing the pressures too high with a sub 26" barrel. Being how that thread is from 2012, and there isn't a lot of new info, it appears that people just stuck with the less efficient 7-08 and 7-08AI.
Link Posted: 7/16/2015 7:09:19 PM EDT
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Originally Posted By steinhab:


Do you have a link to it? I'd like to look into it.
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Originally Posted By steinhab:
Originally Posted By capreppy:
Originally Posted By steinhab:
Originally Posted By capreppy:
I've seen a LOT of posts on the 6 Creedmoor and would be interested in a 7 Creedmoor.

Donuts are somewhat easily rectified with neck turning. The 162 Amax would be an awesome projectile for this cartridge. Be very interested in what others have to say.


Can you neck turn the inside of the neck, near the shoulder? Because I think that's where the donut forms. Some people have said that because of the Amax's shape and that it is usually loaded long, the donuts don't even matter.

http://www.singleactions.com/images/Neck_Donut.jpg



Yes, K&M makes a cutting arbor that would easily solve that problem.


Do you have a link to it? I'd like to look into it.


https://www.kmshooting.com/catalog/with-carbide-cutting-pilot-and-carbide-cutter/micro-adjustable-neck-turner-complete-with-carbide-cutting-pilot_carbide-cutter_and-shell-holder.html

This is one of many options. The cutting pilot does exactly what I described above.
Link Posted: 7/17/2015 9:48:24 AM EDT
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Originally Posted By capreppy:

https://www.kmshooting.com/catalog/with-carbide-cutting-pilot-and-carbide-cutter/micro-adjustable-neck-turner-complete-with-carbide-cutting-pilot_carbide-cutter_and-shell-holder.html

This is one of many options. The cutting pilot does exactly what I described above.
View Quote


Thanks
Link Posted: 7/17/2015 9:59:48 AM EDT
I've been conversing with Phillip Grady, creator of the 7mm Grady Precision Cartridge (GPC), a wildcat pretty much identical to the 7mm Creedmoor. He gave me permission to post parts of our email exchange:

In terms of basic case prep:

My favorite way, but also the most difficult is to take Lapua 308 Palma(In
my experience the small primer pocket provides better consistency,
accuracy, and produces higher velocities), sort it by most consistent
weight, trim it to length, resize it to 30TC, neck it down to 7mm, trim to
length again, turn the necks to proper uniform thickness(or you can inside
neck ream after first firing if you prefer), check brass for proper
concentricity, anneal, then fireform. After 3-4 fireformings the brass
will be perfect. Then anneal and trim as needed. This is the method I use
for my competition rifles.

For our hunting rifles we usually use 30TC brass(I have a lot of this
lying around), neck it down to 7mm, trim to length, sort by weight and
concentricity, anneal, load them and start shooting.

Another common method is using 6.5 creedmoor brass(being made by norma and
nosler now), same process as with the 30TC brass just necking up instead
of down.

Additionally you can use any offspring cartridge of the 308 but if you are
looking for a good combination of accuracy and ease I would go with the
norma or the nosler 6.5 creedmoor brass. This will give you really good
accuracy with far simpler and faster case preparation...

Any time you neck a cartridge up or down there is potential for donuts to
occur in the neck of the brass. Depending on the level of precision you
are after this may or may not be an issue. The only way to remedy this is
to either turn the necks or inside neck ream them (or both) to a uniform
thickness. But first you need a precision tool to check the concentricity
and to insure you are getting them all the same.
View Quote



So overall it seems a bit complicated in terms of reloading. As I barely know what I'm doing in that regards, the cartridge might be a bit out of depth for me. But for ballistics, it is definitely superior to .308, .260, and even 6.5 Creedmoor, its probably the best non-magnum short action cartridge available in terms of external ballistics.

I wish they SAAMI spec'ed the 7mm Creedmoor or someone made brass for it that was competitively priced with regular 6.5 Creedmoor brass. How is this not more popular?
Link Posted: 7/17/2015 3:01:38 PM EDT
What would a good estimate for barrel life be, would it be in-between the 6.5creedmoor/260 and 308 or shorter more like a 6mm creedmoor/243? I've been hoping for something in a short action to take better advantage of those heavier 7mm bullets out there. Hopefully we'll see 7 Creedmoor and 7x47 Lapua starting to gain more popularity.
Link Posted: 7/17/2015 3:22:47 PM EDT
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Originally Posted By Brosome:
What would a good estimate for barrel life be, would it be in-between the 6.5creedmoor/260 and 308 or shorter more like a 6mm creedmoor/243? I've been hoping for something in a short action to take better advantage of those heavier 7mm bullets out there. Hopefully we'll see 7 Creedmoor and 7x47 Lapua starting to gain more popularity.
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Just from what I read its about 2-3000. But that would definitely depend on how hot rounds are being loaded and other factories like firing rate, cleaning, barrel hardness and make, etc.
Link Posted: 7/17/2015 3:26:04 PM EDT
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Originally Posted By steinhab:


Can you neck turn the inside of the neck, near the shoulder? Because I think that's where the donut forms. Some people have said that because of the Amax's shape and that it is usually loaded long, the donuts don't even matter.

http://www.singleactions.com/images/Neck_Donut.jpg

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Originally Posted By steinhab:
Originally Posted By capreppy:
I've seen a LOT of posts on the 6 Creedmoor and would be interested in a 7 Creedmoor.

Donuts are somewhat easily rectified with neck turning. The 162 Amax would be an awesome projectile for this cartridge. Be very interested in what others have to say.


Can you neck turn the inside of the neck, near the shoulder? Because I think that's where the donut forms. Some people have said that because of the Amax's shape and that it is usually loaded long, the donuts don't even matter.

http://www.singleactions.com/images/Neck_Donut.jpg


When you turn the neck properly, you cut into the shoulder a little and the donut pops to the outside.
Link Posted: 7/17/2015 4:08:52 PM EDT
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Originally Posted By ziarifleman:

When you turn the neck properly, you cut into the shoulder a little and the donut pops to the outside.
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Originally Posted By ziarifleman:
Originally Posted By steinhab:
Originally Posted By capreppy:
I've seen a LOT of posts on the 6 Creedmoor and would be interested in a 7 Creedmoor.

Donuts are somewhat easily rectified with neck turning. The 162 Amax would be an awesome projectile for this cartridge. Be very interested in what others have to say.


Can you neck turn the inside of the neck, near the shoulder? Because I think that's where the donut forms. Some people have said that because of the Amax's shape and that it is usually loaded long, the donuts don't even matter.

http://www.singleactions.com/images/Neck_Donut.jpg


When you turn the neck properly, you cut into the shoulder a little and the donut pops to the outside.


I'm new to reloading, that kind of went right over my head. So if you reform the brass and a donut forms on the inside, how will neck turning, which I thought was shaving the outside of the neck for concentricity. How will shaving the outside remove a donut from the inside?
Link Posted: 7/17/2015 4:50:47 PM EDT
I'll try to answer that tonight when I get on a real computer.
Link Posted: 7/17/2015 4:55:33 PM EDT
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Originally Posted By ziarifleman:
I'll try to answer that tonight when I get on a real computer.
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Appreciate it.
Link Posted: 7/17/2015 5:47:17 PM EDT
Why not follow the SLR LINE OF THOUGHT?

6.5. Slr.   260, 243, 7/08 brass. One pass through the die, trim and shoot.  

6 SLR.   243 brass  same thing
Link Posted: 7/17/2015 5:51:31 PM EDT
[Last Edit: 7/17/2015 5:53:18 PM EDT by steinhab]
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Originally Posted By StockDog:
Why not follow the SLR LINE OF THOUGHT?

6.5. Slr.   260, 243, 7/08 brass. One pass through the die, trim and shoot.  

6 SLR.   243 brass  same thing
View Quote


How well does that fit mag length? That's one of the problems with the 260/7-08 cartridges, they have issues fitting in normal mags. What is normal COAL for a VLD bullet in a 6.5 SLR?
Link Posted: 7/17/2015 6:16:34 PM EDT
They depends on the reamer. Whitleys got a reamer that works best for AICS mags and one for gas guns restricted to a 2.8" COAL
Link Posted: 7/19/2015 12:44:18 PM EDT
If you use 139 grain scenars the 260 has no trouble fitting in 2.800 overall length magazines.  I'm getting 2875 fps with 139 grain lapua scenar in a 260 with 42.8 grains of H4350 and had success hitting targets out to 1665 at 750 ft elevation with that load.  I have a hard time believing a heavier bullet can produce a higher velocity in the same size cartridge if both are using appropriate powders.  Using a powder with a "faster" burn rate in the same size case with a heavier bullet usually increases pressure, but not muzzle velocity.  The slower burning powder that can reach max safe pressure with the case completely full is usually the one that gives the highest safe muzzle velocity.  So I think you are making a mistake by basing your expectations for that caliber off of that one source of information.  The guy could have been trashing brass after a single firing and flirting with disaster for all you know.

Of all the 7mm's that can be run in a short action I would go with a 284.  There is a reason it is the hot item in 1000 yard f class right now.  Most of them are necking up 6.5-284 lapua brass.  If it wasn't for barrel life I would have a 6.5-284 right now, but I am in the planning stages of a 284 build.  The problem with a 284 in a short action is it will be single loaded and may have to remove the bolt to extract a loaded round.  In F class this is not a problem.  The truth is I wouldn't be afraid of a long action either I don't know why people think of them as the devil.
Link Posted: 7/19/2015 5:09:07 PM EDT
[Last Edit: 7/19/2015 5:09:38 PM EDT by steinhab]
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Originally Posted By lefty-weaver-g19:
If you use 139 grain scenars the 260 has no trouble fitting in 2.800 overall length magazines.  I'm getting 2875 fps with 139 grain lapua scenar in a 260 with 42.8 grains of H4350 and had success hitting targets out to 1665 at 750 ft elevation with that load.  I have a hard time believing a heavier bullet can produce a higher velocity in the same size cartridge if both are using appropriate powders.  Using a powder with a "faster" burn rate in the same size case with a heavier bullet usually increases pressure, but not muzzle velocity.  The slower burning powder that can reach max safe pressure with the case completely full is usually the one that gives the highest safe muzzle velocity.  So I think you are making a mistake by basing your expectations for that caliber off of that one source of information.  The guy could have been trashing brass after a single firing and flirting with disaster for all you know.

Of all the 7mm's that can be run in a short action I would go with a 284.  There is a reason it is the hot item in 1000 yard f class right now.  Most of them are necking up 6.5-284 lapua brass.  If it wasn't for barrel life I would have a 6.5-284 right now, but I am in the planning stages of a 284 build.  The problem with a 284 in a short action is it will be single loaded and may have to remove the bolt to extract a loaded round.  In F class this is not a problem.  The truth is I wouldn't be afraid of a long action either I don't know why people think of them as the devil.
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I think its the shoulder angle of the Creedmoor/30TC based cartridges that allows for the greater velocities compared to rounds based off the .308 Win case.

The 6.5 creedmoor is a necked down 30TC, which was designed as, and succeeded with, bettering the traditional .308 Win casing. So same bullets, powder, primers, a 30TC would beat out a .308 in velocity. It just never caught on unfortunately.

Link Posted: 7/19/2015 7:45:50 PM EDT
[Last Edit: 7/19/2015 7:56:16 PM EDT by SuperJlarge]
Using that logic, a 308 based case converted to AI with a 40 degree shoulder should produce greater velocity and allow for more case capacity. It's not uncommon for a 260AI to push 140's at 2950 safely. They can fit typical DBM mags too. In addition, there's a lot of choices for brass which may make it cheaper.

If I was building a gas gun, a shorter cartridge like the 6.5cm/7cm would be at the top of the list. For a bolt gun, there's nothing wrong with sticking to a .308 based case.

Link Posted: 7/19/2015 10:02:24 PM EDT
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Originally Posted By SuperJlarge:
Using that logic, a 308 based case converted to AI with a 40 degree shoulder should produce greater velocity and allow for more case capacity. It's not uncommon for a 260AI to push 140's at 2950 safely. They can fit typical DBM mags too. In addition, there's a lot of choices for brass which may make it cheaper.

If I was building a gas gun, a shorter cartridge like the 6.5cm/7cm would be at the top of the list. For a bolt gun, there's nothing wrong with sticking to a .308 based case.

View Quote


For a .260 to compete with a 6.5 Creedmoor it needs a DBM chassis for longer COAL and it needs Ackley Improved chambering for higher velocities. Difficult meaning custom barreled rifles and hand loaded ammo. Versus the common and available 6.5 Creedmoor which is sold everywhere.

7-08 suffers the same shoulder angle/lower velocity problems of the .260 as well as even more problems with COAL. A 7mm Creedmoor/GPC seems to be vastly superior in ballistics but it's even more complicated to get a rifle and ammo than .260 AI.

Hopefully someone SAAIMI specs the 7mm Creedmoor and its own case is released.  It would make one of the best SA calibers available for bolt and gas guns.
Link Posted: 7/20/2015 12:03:24 AM EDT
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Originally Posted By steinhab:


For a .260 to compete with a 6.5 Creedmoor it needs a DBM chassis for longer COAL and it needs Ackley Improved chambering for higher velocities. Difficult meaning custom barreled rifles and hand loaded ammo. Versus the common and available 6.5 Creedmoor which is sold everywhere.
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Originally Posted By steinhab:
Originally Posted By SuperJlarge:
Using that logic, a 308 based case converted to AI with a 40 degree shoulder should produce greater velocity and allow for more case capacity. It's not uncommon for a 260AI to push 140's at 2950 safely. They can fit typical DBM mags too. In addition, there's a lot of choices for brass which may make it cheaper.

If I was building a gas gun, a shorter cartridge like the 6.5cm/7cm would be at the top of the list. For a bolt gun, there's nothing wrong with sticking to a .308 based case.



For a .260 to compete with a 6.5 Creedmoor it needs a DBM chassis for longer COAL and it needs Ackley Improved chambering for higher velocities. Difficult meaning custom barreled rifles and hand loaded ammo. Versus the common and available 6.5 Creedmoor which is sold everywhere.


I'll have to disagree. I've ran a 6.5cm and 260 Savage 12LRP. No issues feeding either. The 260 actually had higher velocity.  Corbon 260 139 loads can achieve 2820-2840 from a 26" barrel. I'm not sure how much experience that you have with the 260, 6.5cm and 6.5x47, but their velocity and ballistics are very similar.

Link Posted: 7/20/2015 9:38:53 AM EDT
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Originally Posted By SuperJlarge:


I'll have to disagree. I've ran a 6.5cm and 260 Savage 12LRP. No issues feeding either. The 260 actually had higher velocity.  Corbon 260 139 loads can achieve 2820-2840 from a 26" barrel. I'm not sure how much experience that you have with the 260, 6.5cm and 6.5x47, but their velocity and ballistics are very similar.

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Originally Posted By SuperJlarge:
Originally Posted By steinhab:
Originally Posted By SuperJlarge:
Using that logic, a 308 based case converted to AI with a 40 degree shoulder should produce greater velocity and allow for more case capacity. It's not uncommon for a 260AI to push 140's at 2950 safely. They can fit typical DBM mags too. In addition, there's a lot of choices for brass which may make it cheaper.

If I was building a gas gun, a shorter cartridge like the 6.5cm/7cm would be at the top of the list. For a bolt gun, there's nothing wrong with sticking to a .308 based case.



For a .260 to compete with a 6.5 Creedmoor it needs a DBM chassis for longer COAL and it needs Ackley Improved chambering for higher velocities. Difficult meaning custom barreled rifles and hand loaded ammo. Versus the common and available 6.5 Creedmoor which is sold everywhere.


I'll have to disagree. I've ran a 6.5cm and 260 Savage 12LRP. No issues feeding either. The 260 actually had higher velocity.  Corbon 260 139 loads can achieve 2820-2840 from a 26" barrel. I'm not sure how much experience that you have with the 260, 6.5cm and 6.5x47, but their velocity and ballistics are very similar.



There is definitely some inaccurate information being spread here by the OP.  I can only speak about things I've actually done, but a 260 loaded with 139 grain lapua scenars has no problem feeding from a standard magazine or even the factory internal box magazine of a Remington 700.  From everything I've seen the muzzle velocity of a 6.5 creedmoor and a 260 rem are identical.  The 260 actually has a slightly larger case capacity.  You can find outliers from either caliber to show much higher or lower than normal velocities, but taking an average you will find they are nearly identical.  Getting 2850 fps out of either a 260 or 6.5 creedmoor is pretty common out of a 24-26" barrel.  So I don't know where you got the idea that the creedmoor produces higher velocities than the 260.

Lapua makes brass for the 260 which is easy to find, but you can also make brass from 308 which is every where.

As far as the 7mm options I prefer the 284 win.  Launching a 180 grain bullet at 2900+ fps out of a short or long action with good barrel life.

Link Posted: 7/20/2015 10:40:12 AM EDT
[Last Edit: 7/20/2015 11:12:19 AM EDT by steinhab]
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Originally Posted By SuperJlarge:


I'll have to disagree. I've ran a 6.5cm and 260 Savage 12LRP. No issues feeding either. The 260 actually had higher velocity.  Corbon 260 139 loads can achieve 2820-2840 from a 26" barrel. I'm not sure how much experience that you have with the 260, 6.5cm and 6.5x47, but their velocity and ballistics are very similar.

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Originally Posted By SuperJlarge:
Originally Posted By steinhab:
Originally Posted By SuperJlarge:
Using that logic, a 308 based case converted to AI with a 40 degree shoulder should produce greater velocity and allow for more case capacity. It's not uncommon for a 260AI to push 140's at 2950 safely. They can fit typical DBM mags too. In addition, there's a lot of choices for brass which may make it cheaper.

If I was building a gas gun, a shorter cartridge like the 6.5cm/7cm would be at the top of the list. For a bolt gun, there's nothing wrong with sticking to a .308 based case.



For a .260 to compete with a 6.5 Creedmoor it needs a DBM chassis for longer COAL and it needs Ackley Improved chambering for higher velocities. Difficult meaning custom barreled rifles and hand loaded ammo. Versus the common and available 6.5 Creedmoor which is sold everywhere.


I'll have to disagree. I've ran a 6.5cm and 260 Savage 12LRP. No issues feeding either. The 260 actually had higher velocity.  Corbon 260 139 loads can achieve 2820-2840 from a 26" barrel. I'm not sure how much experience that you have with the 260, 6.5cm and 6.5x47, but their velocity and ballistics are very similar.



Corbon list the MV of its 260 139 Lapua scenar load at 2750, which is far less than what your claiming.
Corbon 260/139 scenar
Link Posted: 7/20/2015 12:49:16 PM EDT
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Originally Posted By steinhab:


Corbon list the MV of its 260 139 Lapua scenar load at 2750, which is far less than what your claiming.
Corbon 260/139 scenar
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Originally Posted By steinhab:
Originally Posted By SuperJlarge:
Originally Posted By steinhab:
Originally Posted By SuperJlarge:
Using that logic, a 308 based case converted to AI with a 40 degree shoulder should produce greater velocity and allow for more case capacity. It's not uncommon for a 260AI to push 140's at 2950 safely. They can fit typical DBM mags too. In addition, there's a lot of choices for brass which may make it cheaper.

If I was building a gas gun, a shorter cartridge like the 6.5cm/7cm would be at the top of the list. For a bolt gun, there's nothing wrong with sticking to a .308 based case.



For a .260 to compete with a 6.5 Creedmoor it needs a DBM chassis for longer COAL and it needs Ackley Improved chambering for higher velocities. Difficult meaning custom barreled rifles and hand loaded ammo. Versus the common and available 6.5 Creedmoor which is sold everywhere.


I'll have to disagree. I've ran a 6.5cm and 260 Savage 12LRP. No issues feeding either. The 260 actually had higher velocity.  Corbon 260 139 loads can achieve 2820-2840 from a 26" barrel. I'm not sure how much experience that you have with the 260, 6.5cm and 6.5x47, but their velocity and ballistics are very similar.



Corbon list the MV of its 260 139 Lapua scenar load at 2750, which is far less than what your claiming.
Corbon 260/139 scenar

I notice that your link didn't specify a barrel length, while my quote did. 2748fps has been reported from the Corbon 139's in a 22" barrel. I STRONGLY suggest you read up more on the common loadings of the 260, 6.5 and 6x47 before making more wild claims.
Velocity Test
Link Posted: 7/20/2015 2:44:26 PM EDT
[Last Edit: 7/20/2015 2:45:39 PM EDT by steinhab]
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Originally Posted By SuperJlarge:

I notice that your link didn't specify a barrel length, while my quote did. 2748fps has been reported from the Corbon 139's in a 22" barrel. I STRONGLY suggest you read up more on the common loadings of the 260, 6.5 and 6x47 before making more wild claims.
Velocity Test
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This info comes from Corbon's website itself and states MV is 2750fps with a 24" barrel weight. Stop getting defensive over a cartridge, I'm not making anything up, I'm not making wild claims. If you don't agree with Corbon's own claims, go notify them. If you have further issues that you want to get defensive over, save it for another thread.
Link Posted: 7/20/2015 3:13:31 PM EDT
Not being defensive, but making sure accurate info is presented. This is a tech forum. I'm showing data that supports a 260 at 2820-2840fps with factory loads from a 26" barrel. The 6.5cm Hornady 140amax loads are rated at 2810fps in a 26" tube if memory serves correct. I think initially they were rated at 2710 from a 24" barrel. Unless Hornady has changed their 24" barrel velocities, which may have happened due to powder changes, the two examples in 24" barrels confirms that the 260 is equal or slightly faster with comparable bullets in factory loaded ammo.
Link Posted: 7/21/2015 9:17:14 AM EDT
Link Posted: 7/21/2015 9:48:02 AM EDT
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Originally Posted By steinhab:


I'm new to reloading, that kind of went right over my head. So if you reform the brass and a donut forms on the inside, how will neck turning, which I thought was shaving the outside of the neck for concentricity. How will shaving the outside remove a donut from the inside?
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Originally Posted By steinhab:
Originally Posted By ziarifleman:
Originally Posted By steinhab:
Originally Posted By capreppy:
I've seen a LOT of posts on the 6 Creedmoor and would be interested in a 7 Creedmoor.

Donuts are somewhat easily rectified with neck turning. The 162 Amax would be an awesome projectile for this cartridge. Be very interested in what others have to say.


Can you neck turn the inside of the neck, near the shoulder? Because I think that's where the donut forms. Some people have said that because of the Amax's shape and that it is usually loaded long, the donuts don't even matter.

http://www.singleactions.com/images/Neck_Donut.jpg


When you turn the neck properly, you cut into the shoulder a little and the donut pops to the outside.


I'm new to reloading, that kind of went right over my head. So if you reform the brass and a donut forms on the inside, how will neck turning, which I thought was shaving the outside of the neck for concentricity. How will shaving the outside remove a donut from the inside?


I'd also like to hear this explained.  I've heard this said before, but I also can't make any sense of how it would actually work.
Link Posted: 7/21/2015 12:37:07 PM EDT
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Originally Posted By steinhab:


How well does that fit mag length? That's one of the problems with the 260/7-08 cartridges, they have issues fitting in normal mags. What is normal COAL for a VLD bullet in a 6.5 SLR?
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Originally Posted By steinhab:
Originally Posted By StockDog:
Why not follow the SLR LINE OF THOUGHT?

6.5. Slr.   260, 243, 7/08 brass. One pass through the die, trim and shoot.  

6 SLR.   243 brass  same thing


How well does that fit mag length? That's one of the problems with the 260/7-08 cartridges, they have issues fitting in normal mags. What is normal COAL for a VLD bullet in a 6.5 SLR?


It will seat the longer bullets at standard maglength just like creedmoor.  Same case length but slightly longer neck.  

The shoulder is bumped back just like the creedmore but cases are made with one pass through tge die.  No fireforming needed.  

Personally, I debate going creedmore but I want to be able to make brass from commonly available components like .243 or 7/08 brass.  Creedmoor is great but if you try to make from .308 based cases there are several steps in the process and you may still need fireforming.
Link Posted: 7/21/2015 12:43:08 PM EDT
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Originally Posted By StockDog:

It will seat the longer bullets at standard maglength just like creedmoor.  Same case length but slightly longer neck.  

The shoulder is bumped back just like the creedmore but cases are made with one pass through tge die.  No fireforming needed.  

Personally, I debate going creedmore but I want to be able to make brass from commonly available components like .243 or 7/08 brass.  Creedmoor is great but if you try to make from .308 based cases there are several steps in the process and you may still need fireforming.
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So the 6.5 SLR is just reformed .243 brass? No donut issues? Does Lapua .243 brass work? Sounds like this round might be better than 6.5 Creedmoor for shooters that are willing to build a custom rifle and reload their ammo.

Has anyone created a 7mm  Super LR yet?
Link Posted: 7/21/2015 1:45:18 PM EDT
I was thinking 7mmSLR as well.  

Here's more info.
link
http://www.6mmar.com/site/mobile?url=http%3A%2F%2Fwww.6mmar.com%2FBarrels.php#3018
Link Posted: 7/21/2015 1:51:56 PM EDT
Actually, I was wrong.  

It basically sets back the shoulder and increases the neck length to accommodate higher BC bullets without having the bullets take up case capacity.  

If you read further on the link it does a good job of explaining this.
Link Posted: 7/30/2018 1:11:21 AM EDT
Very interested in this!
Link Posted: 7/30/2018 10:09:42 AM EDT
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Originally Posted By badkarmaiii:
Very interested in this!
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3 year old thread, and this stuff hasn't gotten anymore popular than it was then.
Link Posted: 8/18/2018 3:30:22 AM EDT
I'd love a DPMS GII -in 7mm GPC!
Link Posted: 2/3/2019 8:48:27 PM EDT
Took my new 7mm SAW AR to the range today for the first time.
It's like a 7mm SLR, only pushing the shoulder steeper and the neck longer from 308 brass.
Only had 20 rounds of ammo loaded by my friend.
He doesn't have any good powders for it so velocity was only 2509 avg with 162gr ELD-M.
Group was half MOA or so.
Shot smooth and hit the 800 and 1000 yard targets when I called the wind correctly.
Better powders should get around 2700 fps from my 24" 3-groove Deadshot Barrels custom barrel.
So far, I'm pleased with the results despite it not being too expensive.
Link Posted: 2/3/2019 10:23:03 PM EDT
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Originally Posted By steinhab:
I'm new to reloading, that kind of went right over my head. So if you reform the brass and a donut forms on the inside, how will neck turning, which I thought was shaving the outside of the neck for concentricity. How will shaving the outside remove a donut from the inside?
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Originally Posted By steinhab:
Originally Posted By ziarifleman:
Originally Posted By steinhab:
Originally Posted By capreppy:
I've seen a LOT of posts on the 6 Creedmoor and would be interested in a 7 Creedmoor.

Donuts are somewhat easily rectified with neck turning. The 162 Amax would be an awesome projectile for this cartridge. Be very interested in what others have to say.
Can you neck turn the inside of the neck, near the shoulder? Because I think that's where the donut forms. Some people have said that because of the Amax's shape and that it is usually loaded long, the donuts don't even matter.

http://www.singleactions.com/images/Neck_Donut.jpg
When you turn the neck properly, you cut into the shoulder a little and the donut pops to the outside.
I'm new to reloading, that kind of went right over my head. So if you reform the brass and a donut forms on the inside, how will neck turning, which I thought was shaving the outside of the neck for concentricity. How will shaving the outside remove a donut from the inside?
Maybe this will help, if you notice on the cut case the cutter just gets into the shoulder of the case...when fired this thin spot allows case pressure to push the neck material outward instead of allowing a internal bulge to form...

Attachment Attached File


On to the second case and you can see after being fired a few times you cannot see the cut line anymore since the pressure has pushed the case outwards...

Attachment Attached File


What I have found is case trim length(case head to shoulder) becomes very very important for neck turning and where the cutter stops in relation to the shoulder in order to get consistent results from case to case...Also the RCBS 3 angle cutter does have a cutter on the internal mandrel ..

Attachment Attached File


Attachment Attached File


Attachment Attached File
Link Posted: 2/4/2019 4:31:48 PM EDT
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Originally Posted By badkarmaiii:
Took my new 7mm SAW AR to the range today for the first time.
It's like a 7mm SLR, only pushing the shoulder steeper and the neck longer from 308 brass.
Only had 20 rounds of ammo loaded by my friend.
He doesn't have any good powders for it so velocity was only 2509 avg with 162gr ELD-M.
Group was half MOA or so.
Shot smooth and hit the 800 and 1000 yard targets when I called the wind correctly.
Better powders should get around 2700 fps from my 24" 3-groove Deadshot Barrels custom barrel.
So far, I'm pleased with the results despite it not being too expensive.
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So I went this route, with a 7-08 just to see what it could do.

I have run the numbers to death on this.

7mm anything doesn't make sense unless you are running a bullet with a G1 BC of at least .7.

So this means 180 ELD-Ms, as they have a G1 BC of .79.

Now in order for this to make sense over 6.5 CM, 6.5 x 47 or a .260, the 7mm 180gr. ELD has to be going at least 2,650+ FPS.

Problem is that the 180gr. ELD is too long, so now even with AI mags, case capacity becomes a problem in short actions.

There isn't enough powder to get that speed from either the Creedmoor or .308 case to push a 180gr. 7mm bullet to those speeds.

Fastest I was able to go was 2,600 FPS from a 24" barrel.  However, the accuracy was best at 2,550 FPS.

You run the numbers on a 180gr. ELDM @ 2,550 FPS and it is inferior to the 6.5mm options.

The other negative I noticed was there is a significant recoil increase over a 6.5mm.

This was an interesting but expensive dead end for me.
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