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Posted: 8/18/2010 9:46:28 PM EDT
[Last Edit: 8/18/2010 9:51:20 PM EDT by RuLins05]
I have an itch and from what I've read so do most of the members of this forum and if you don't think you do you're still in denial. So when I say I want to build a non 308 large frame rifle, its not because I don't want a 308, its that my safe isn't full. Anyway, I've been debating between a 243 Win and a 260 Rem for a DPMS LR build and I think I've settled on the 260 Remington unless I can be swayed, but this is not the purpose of this thread. What I want to know is what barrel? I like the 24" ss bull but they are heavy (I have an LR-308 and holy crap). Is the 24" needed or at least beneficial compared to a 20" heavy. What if I got the 24" re-profiled, or what? Does dimpling remove more weight than fluting? If I do get it re-profiled, I assume ADCO? (had them thread a barrel and it looked NICE!) Thanks in advance for your help!
Link Posted: 8/18/2010 9:51:01 PM EDT
As I understand it 6.5 Creedmoor fits better in magazines.
Link Posted: 8/18/2010 10:02:19 PM EDT
Really? I thought the 6.5 was actually longer than the .260? I really didn't want to go with the Creedmoor because of the age of the round (will it last) and the fact that the price/availability issues aren't really justified by the difference in performance.
Link Posted: 8/18/2010 11:14:46 PM EDT
I went with the 260 rem for the ballistics compared to the 308 (lighter projectiles).

As for profiles, If you're doing benchrest shooting paper then leave it SS bull (which I did).

If you're wanting to use it for hunting, aesthetics, weight, etc. then reprofile it.

I like mine the way it is, but might just thread the muzzle and do a recessed crown.
Link Posted: 8/19/2010 2:11:59 AM EDT
Originally Posted By RuLins05:
Really? I thought the 6.5 was actually longer than the .260? I really didn't want to go with the Creedmoor because of the age of the round (will it last) and the fact that the price/availability issues aren't really justified by the difference in performance.


I have both the 260 and the Creedmoor in 24 inch. Yes, the 24" is god-aweful heavy. What barrel you want really depends on what you want the rifle for, obviously.

On the price/availability issue, the Creedmoor isn't as bad an option as you might initially think.

1. For some reason, you can currently buy DPMS 6.5 Creedmoor 24" complete rifles for just under $1000 –– at least a couple of hundred less than you will pay for an identical rifle barreled in 260.

2. If you are building, the component prices (the barrel is the only thing that is different) are the same.

3. Ammunition availability for the 6.5 Creedmoor has been an issue, but the options are beginning to grow.....and Hornady's complete line of 6.5 Creedmoor ammo is a good bit cheaper than just about everything you can buy in 260.
Link Posted: 8/19/2010 8:04:39 AM EDT
[Last Edit: 8/19/2010 8:05:48 AM EDT by RuLins05]
So if i were to get it re-profiled could I leave the 24" length or would some of that have to go. DPMS doesn't sell their Creedmoor barrels and I have already assembled lots of parts for this build hence another reason I would like to stay 260 or 243 rather than the Creedmoor. Its easier on my wife if I only spend a couple hundred every now and then rather than a grand all at once.

bowslngr - having both which do you prefer?

Does anyone else offer Creedmoor barrels for the DPMS platform?
Link Posted: 8/19/2010 9:13:59 AM EDT
Yes, you could re-profile and leave the length at 24" if you wanted to.

I was surprised to see that DPMS is not selling their Creedmoor barrels. I could swear I saw them for sale on the DPMS site about two months ago when I was contemplate the buy vs build decision when I was looking for one for my dad.

I can appreciate your position on spending a little at a time vs. it all at once. That said, I just looked at R&R arms and they are selling the complete Creedmoor rifle (although I don't believe it is fluted) for $934. That is several hundred cheaper that you are going to be able to build the similar DPMS 260 for.
Link Posted: 8/19/2010 10:23:56 AM EDT
Well another advantage to building slowly is that I get to buy items when they are on sale or when I'm already going to order something else

TM Lower 200
DPMS LKP 58 - Midwayusa
Gas Block .936 20 - Midwayusa
RRA A2 Stock w/tube, screw/spacer 45 - RRA
DPMS 308 Buffer/Spring from EE 15 - ARFcom
DPMS 260 24" ss barrel 205 - JSESurplus
DPMS A3 Assembled Upper 165 - JSESurplus
DPMS BCG 210 - JSESurplus
DPMS Rilfe Length gas tube w/pin 10 - JSESurplus
Free Float ventilated Handguard FREE - Some guy at the range

Total of $928

Now if I reprofile the barrel there will be an increase around $100 and I have enough magazines to arm the Chinese! To keep shipping down I only order when I need a refill on reloading supplies or whatever that way shipping goes up by one or two dollars or shop at places like RRA where no shipping is charged, but back to the issue at hand when you send a barrel to be reprofiled are the dimensions predetermined or do I have to specify? If I do have to specify what should I ask for?
Link Posted: 8/19/2010 10:38:54 AM EDT
This is something I'm also looking at doing. I would like a large frame 6.5 AR and both the .260 and the 6.5 Creedmore have the performance I'm looking for.

I think I'm going to go with the .260 because even if the round fails and factory ammo goes away completely I can still form brass from another member of the .308 family (.260 is just a necked down .308 if I'm not mistaken). I don't think that is an option for the Creedmore and you would have to obtain brass specific to that application.

Someone please correct me if I'm wrong. This is just what I've come across doing research on these two cartridges.
Link Posted: 8/19/2010 11:12:58 AM EDT
Originally Posted By Combat_Jack:
As I understand it 6.5 Creedmoor fits better in magazines.


I don't see how the creedmore would work in .308 mags better then a round that uses a .308 case necked to .264.

I used to build rifles for DPMS, I built myself a REPR in .260 shortly before I left. everything was std to the REPR but I had a one off bbl made by Kreiger , 24" SST heavy bull with no taper and 11degree target crown.

I did deer hunt with it last year (got 2 with it) and its really not that bad with a decent sling, half mile walk to my deer stand BTW. but if you want it lighter I would definitely get a lighter profile then a shorter bbl, when you see what it can do you will want all the MV that you can get.
rather then having a bbl turned smaller, why not just get one from Kreiger or another bbl maker that is already the profile you want? the std ones are about $300ish right from Kreiger(mine cost me nearly $800)

Link Posted: 8/19/2010 11:58:25 AM EDT
Okay thats one sick rifle, but if I spent any where near that on my barrel my wife would use it on me before I even got it together! I checked Kreiger's site and it quotes $400 plus $100 for chambering, any other barrel manufactures out there for the 260 Rem in the DPMS platform? What are the disadvantages to getting it profiled say to a heavy barrel rather than a bull (other than the barrel will heat up quicker I don't plan on any rapid fire)?
Link Posted: 8/19/2010 12:48:08 PM EDT
Originally Posted By RuLins05:
Okay thats one sick rifle, but if I spent any where near that on my barrel my wife would use it on me before I even got it together! I checked Kreiger's site and it quotes $400 plus $100 for chambering, any other barrel manufactures out there for the 260 Rem in the DPMS platform? What are the disadvantages to getting it profiled say to a heavy barrel rather than a bull (other than the barrel will heat up quicker I don't plan on any rapid fire)?


I can't help you on barrel manufacturers but when it comes to barrel profile here's how it breaks down:

The thinner the barrel the faster it heats up and the faster it cools down. A heavier barrel has more mass so it heats up slower but it also has less surface area per unit of mass so it cools slower as well. Fluting a heavy barrel mitigates this as it reduces mass but adds surface area. Fluting also makes the barrel more rigid (more on that later).

The other major difference is in accuracy. The thicker a barrel is for a given length the more rigid it will be, making it more accurate. A longer barrel is not more accurate than a short barrel, it just provides more time for the expanding gasses to work on the bullet giving increases in muzzle velocity. In theory if two barrels were exactly the same except one was 16" and the other was 24" the 16" would be more rigid and theoretically more accurate as rigidity reduces harmonics and barrel flex. As mentioned above, fluting can increase rigidity of the barrel while also reducing weight and adding surface area.

In the end, accuracy is more dependant on the quality of the barrel than the profile. Given two barrels of equal quality and length the thicker barrel should be more accurate than the thin barrel.
Link Posted: 8/19/2010 7:15:05 PM EDT
Originally Posted By Altair:
This is something I'm also looking at doing. I would like a large frame 6.5 AR and both the .260 and the 6.5 Creedmore have the performance I'm looking for.

I think I'm going to go with the .260 because even if the round fails and factory ammo goes away completely I can still form brass from another member of the .308 family (.260 is just a necked down .308 if I'm not mistaken). I don't think that is an option for the Creedmore and you would have to obtain brass specific to that application.

Someone please correct me if I'm wrong. This is just what I've come across doing research on these two cartridges.


The 6.5 Creedmoor is a necked down variant of the .30 TC (Thompson Center). Reference to .30 TC necked down

From what I understand, the .260 Rem cannot be loaded with heavier (=longer) bullets without encroaching on too much capacity or exceeding magazine length (~2.8"). Reference for .260 Remington claim
Link Posted: 8/19/2010 7:57:15 PM EDT
my pet load for my REPR is
140gr Berger Match VLD, 42.8gr IMR 4350 loaded to 2.810COAL MV 2715FPS.
perfect function in both the DPMS steel mags and in the magpull mags. its not a max load, just what is most accurate in my rifle, started to see pressure signs at 43.2gr.
as far as I know, the only bullet that is longer is the 144gr Lapua and I think I saw a 160gr solid but its not something you would be shooting for LR accuracy(RNFB)
Link Posted: 8/20/2010 12:17:16 PM EDT
The advantage to the .260 is that you can use Lapua .243 Win brass to form cases. There is no Lapua brass for the Creedmoor.

Otherwise, the ballistics are the same pretty much. The mag fit is the same as well. Both are great as far as I am concerned. I have had no problems with my .260 AR-10.
Link Posted: 8/20/2010 12:24:02 PM EDT
Originally Posted By FLICK-244:
Originally Posted By Altair:
This is something I'm also looking at doing. I would like a large frame 6.5 AR and both the .260 and the 6.5 Creedmore have the performance I'm looking for.

I think I'm going to go with the .260 because even if the round fails and factory ammo goes away completely I can still form brass from another member of the .308 family (.260 is just a necked down .308 if I'm not mistaken). I don't think that is an option for the Creedmore and you would have to obtain brass specific to that application.

Someone please correct me if I'm wrong. This is just what I've come across doing research on these two cartridges.


The 6.5 Creedmoor is a necked down variant of the .30 TC (Thompson Center). Reference to .30 TC necked down

From what I understand, the .260 Rem cannot be loaded with heavier (=longer) bullets without encroaching on too much capacity or exceeding magazine length (~2.8"). Reference for .260 Remington claim


The 140gr bullets encroach a small amount into the case with the .260. Only you can say weather that matters to you. In a mag fed gun you are going to have to load the creedmoor and the 260 to the same length anyway. To me the lapua brass is a bigger advantage than the slightly larger case capacity of the creedmoor (if any).


Link Posted: 8/20/2010 1:28:28 PM EDT
Originally Posted By Altair:

The thinner the barrel the faster it heats up and the faster it cools down. A heavier barrel has more mass so it heats up slower but it also has less surface area per unit of mass so it cools slower as well. Fluting a heavy barrel mitigates this as it reduces mass but adds surface area. Fluting also makes the barrel more rigid (more on that later).
.


Not sure the physics statements here are all correct, but that is for a whole different debate.

Can someone post pictures of 260 Rem, 6.5 Creedmore and 6.5 x 47 loaded rounds in the mag? That might help some folks, being visual learners.

On the "fluting makes a barrel rigid" - somewhere on these forums a very well written post with all the appropriate equations showed this was a mis-statement. You cannot make something more rigid by removing mass. The comparison has to be accurate: two barrels of same DIAMETER - one fluted, one solid. The solid barrel will be more rigid, but also heavier. Two barrels of same MASS - one fluted, one solid - the solid barrel will have a smaller diameter and as a result will be less rigid. ADDING fluting to an existing barrel will not make it more rigid, on the contrary. However, replacing a solid non-fluted barrel with a fluted barrel of same mass will necessarily require a larger diameter barrel which in turn will mean that the replacement barrel will be more rigid.

Link Posted: 8/20/2010 3:10:18 PM EDT
Originally Posted By MartytW:
Originally Posted By Altair:

The thinner the barrel the faster it heats up and the faster it cools down. A heavier barrel has more mass so it heats up slower but it also has less surface area per unit of mass so it cools slower as well. Fluting a heavy barrel mitigates this as it reduces mass but adds surface area. Fluting also makes the barrel more rigid (more on that later).
.


Not sure the physics statements here are all correct, but that is for a whole different debate.

Can someone post pictures of 260 Rem, 6.5 Creedmore and 6.5 x 47 loaded rounds in the mag? That might help some folks, being visual learners.

On the "fluting makes a barrel rigid" - somewhere on these forums a very well written post with all the appropriate equations showed this was a mis-statement. You cannot make something more rigid by removing mass. The comparison has to be accurate: two barrels of same DIAMETER - one fluted, one solid. The solid barrel will be more rigid, but also heavier. Two barrels of same MASS - one fluted, one solid - the solid barrel will have a smaller diameter and as a result will be less rigid. ADDING fluting to an existing barrel will not make it more rigid, on the contrary. However, replacing a solid non-fluted barrel with a fluted barrel of same mass will necessarily require a larger diameter barrel which in turn will mean that the replacement barrel will be more rigid.



As for the heating up and cooling if a given barrel diameter and length lets look at two examples. For simplicity's sake we'll assume two 20" barrels with .224" bores, one of 1" diameter and one of .5" diameter. I'm not suggesting using .5" as a diameter for a .223 barrel, it is just for illustration purposes. For that matter, I'm not adjusting for surface area of lands and grooves or the chamber etc. I'm also not adding the surface area of the ends of the barrel. This is just an example. I used 3.14 for Pi.

A 20" barrel of 1" diameter would have 14.912 cubic inches of steel (15.7 - .7878 for the bore). This same barrel would have 76.8672 square inches of surface area (62.8 + 14.0672 for the bore). That is a ratio of 5.1547 square inches of surface area per cubic inch of steel.

A 20" barrel of .5" diameter would have 3.1372 cubic inches of steel (3.925 - .7878 for the bore). This barrel would have 45.4672 square inches of surface area (31.4 + 14.0672 for the bore). That is a ratio of 14.4929 square inches of surface area per cubic inch of steel.

The barrel of 1/2 the diamter has almost 3 times the ratio of surface area, which facilitates faster cooling. The drawback is that it has about 1/5 the volume (since density is constant this would translate to mass) so it heats up quicker. This is the reason heavier barrels are better for machine guns. Thin barrels don't have enough mass to soak up the heat and get too hot too fast.

Fluting decreases mass but adds surface area. It also improves the surface area to volume (or mass) ration, making a fluted barrel of the same mass cool quicker even though it can absorb the same amout of heat.

Marty is correct (as usual) that fluting an exsisting barrel does not make it more rigid. If two barrels are of equal mass the fluted one will be more rigid than the traditional round barrel. I should have been more specific.

Formulas:

Volume: Pi * radius squared * length
Surface Area: Pi * diameter * length
Total volume: volume of barrel - volume of bore
Total surface area: area of barrel + area of bore
Link Posted: 8/20/2010 3:13:22 PM EDT
Bring back radial flutes...
Link Posted: 8/21/2010 12:02:43 PM EDT
Originally Posted By MartytW:

Can someone post pictures of 260 Rem, 6.5 Creedmore and 6.5 x 47 loaded rounds in the mag? That might help some folks, being visual learners.


you mean like this?


.260 rem,
Hornaday 140gr interbond SST, 42.8gr IMR4350, 2.810 COAL, MV ~2715FPS...
no powder crunching while seating the bullet, and as you can see, plenty of room in the mag.
Link Posted: 8/21/2010 2:58:42 PM EDT
FYI-
.260 rem bbl's from clasifieds here
Link Posted: 8/22/2010 5:47:31 AM EDT
[Last Edit: 8/22/2010 5:58:18 AM EDT by 320pf]
Originally Posted By FLICK-244:
Originally Posted By Altair:
This is something I'm also looking at doing. I would like a large frame 6.5 AR and both the .260 and the 6.5 Creedmore have the performance I'm looking for.

I think I'm going to go with the .260 because even if the round fails and factory ammo goes away completely I can still form brass from another member of the .308 family (.260 is just a necked down .308 if I'm not mistaken). I don't think that is an option for the Creedmore and you would have to obtain brass specific to that application.

Someone please correct me if I'm wrong. This is just what I've come across doing research on these two cartridges.


The 6.5 Creedmoor is a necked down variant of the .30 TC (Thompson Center). Reference to .30 TC necked down

From what I understand, the .260 Rem cannot be loaded with heavier (=longer) bullets without encroaching on too much capacity or exceeding magazine length (~2.8"). Reference for .260 Remington claim


Actually, If you look at the overall case dimensions you will find the the 30 TCU is closely related to the old 300 Savage that came out circa 1920. In addition, the 300 Savage served as the base cartridge for the 308 Win.

Of course, the 300 Savage was derived from the 250-3000 Savage that came out circa 1915, and all of these are based on the 30-06 case.

If you check out the case dimensions of the 6.5 Creedmore and compare them the the 250 Savage Ackley Improved you will find that all the folks at Hornaday did was basically neck up the 250 Savage Ackley Improved from 0.257 to 0.264.

There is not really that many new things that someone has not already thought about or tried.

320pf
Link Posted: 8/22/2010 5:56:33 AM EDT
Originally Posted By J75player:
no powder crunching while seating the bullet, and as you can see, plenty of room in the mag.


Try the 139 Scenar.
Link Posted: 8/22/2010 7:21:34 AM EDT
Originally Posted By J75player:
Originally Posted By Combat_Jack:
As I understand it 6.5 Creedmoor fits better in magazines.


I don't see how the creedmore would work in .308 mags better then a round that uses a .308 case necked to .264.

I used to build rifles for DPMS, I built myself a REPR in .260 shortly before I left. everything was std to the REPR but I had a one off bbl made by Kreiger , 24" SST heavy bull with no taper and 11degree target crown.
http://i27.photobucket.com/albums/c183/J75player/REPR.jpg
I did deer hunt with it last year (got 2 with it) and its really not that bad with a decent sling, half mile walk to my deer stand BTW. but if you want it lighter I would definitely get a lighter profile then a shorter bbl, when you see what it can do you will want all the MV that you can get.
rather then having a bbl turned smaller, why not just get one from Kreiger or another bbl maker that is already the profile you want? the std ones are about $300ish right from Kreiger(mine cost me nearly $800)



Been meaning to ask - what hand guard is that?
Link Posted: 8/22/2010 9:20:33 AM EDT
[Last Edit: 8/22/2010 9:32:40 AM EDT by J75player]
Originally Posted By MartytW:
Originally Posted By J75player:
Originally Posted By Combat_Jack:
As I understand it 6.5 Creedmoor fits better in magazines.


I don't see how the creedmore would work in .308 mags better then a round that uses a .308 case necked to .264.

I used to build rifles for DPMS, I built myself a REPR in .260 shortly before I left. everything was std to the REPR but I had a one off bbl made by Kreiger , 24" SST heavy bull with no taper and 11degree target crown.
http://i27.photobucket.com/albums/c183/J75player/REPR.jpg
I did deer hunt with it last year (got 2 with it) and its really not that bad with a decent sling, half mile walk to my deer stand BTW. but if you want it lighter I would definitely get a lighter profile then a shorter bbl, when you see what it can do you will want all the MV that you can get.
rather then having a bbl turned smaller, why not just get one from Kreiger or another bbl maker that is already the profile you want? the std ones are about $300ish right from Kreiger(mine cost me nearly $800)



Been meaning to ask - what hand guard is that?


its the DPMS REPR handguard. actualy its one of the prototype forends as i built mine before the REPR was released.

Originally Posted By Combat_Jack:
Originally Posted By J75player:
no powder crunching while seating the bullet, and as you can see, plenty of room in the mag.


Try the 139 Scenar.


i dont have that bullet, but i do use the 140 gr Berger Match VLD's, they area about as long as it gets, still no crunching.
Link Posted: 8/22/2010 10:05:01 AM EDT
I'd go with the 260 Rem, in fact I'm considering a 260 Rem for an extra FAL receiver I have laying around here someplace.
Link Posted: 9/15/2010 8:26:32 PM EDT
Well I went with the 260 Rem with a 24" bull for now. Its pretty freakin sweet. Seems to be pretty accurate with Remington Corelokt 140gr haven' t received my dies yet so factory ammo is all for now. Thanks all for your help
Link Posted: 9/15/2010 9:56:33 PM EDT
what about just cutting down the 24" to a 20 or 18". would a person lose much range with it?
Link Posted: 9/16/2010 6:35:59 AM EDT
Originally Posted By Aramark:
what about just cutting down the 24" to a 20 or 18". would a person lose much range with it?


That would probably cost you 100 to 200 fps which won't cost alot of range. Maybe 100 yards on the far end at the most, which with a .260 is a long way out. Think of the .260 as a Grendel on steriods. The Grendel can shoot to 1000 so a 20" barrel on a .260 will at least get you there. I suspect you could shoot 1000 with a 16" .260 as well.
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