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Posted: 9/11/2017 8:59:25 PM EDT
Hey guys,

I am digging deeper into the never-ending-precision-ammo-making-techniques. New focus is bullet seating depth. I am wanting to know where your sweet spot is on your AR. Maybe you could use this template? Please let me know!

Bullet type and weight:
Caliber:
Distance off lands:
Barrel length and brand:

I have an AR in .223, 6.5G and 6.5C and am curious to know where yall stand. My tools for measuring ogive show up in a few more days so I don't have input yet. I will be making another thread on seating depth with range results here in the next few weeks and they will include Bartlein, Shilen and Larue:)
Link Posted: 9/11/2017 9:09:07 PM EDT
[#1]
In my experience you will run into mag length issues before you are able to get very close to the lands in an AR-15 style rifle...
Link Posted: 9/11/2017 9:30:28 PM EDT
[#2]
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Quoted:
In my experience you will run into mag length issues before you are able to get very close to the lands in an AR-15 style rifle...
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This. Except for 300blk.
Link Posted: 9/11/2017 9:41:19 PM EDT
[#3]
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Quoted:
In my experience you will run into mag length issues before you are able to get very close to the lands in an AR-15 style rifle...
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This
Link Posted: 9/11/2017 9:41:26 PM EDT
[#4]
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Quoted:


This. Except for 300blk.
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Not with ASC mags. They give you a little over 50 thou more room:) I have them for all my AR's
Link Posted: 9/11/2017 10:04:23 PM EDT
[#5]
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Quoted:


Not with ASC mags. They give you a little over 50 thou more room:) I have them for all my AR's
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No sure if you're alluding to .223 or 300blk. Even with .05 extra, most .233 loads won't be into the lands. With 300blk, certain bullets can be into the lands at much less than mag length.
Link Posted: 9/11/2017 10:09:37 PM EDT
[#6]
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Quoted:
In my experience you will run into mag length issues before you are able to get very close to the lands in an AR-15 style rifle...
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^ The man's right, you know!
Link Posted: 9/11/2017 10:12:58 PM EDT
[#7]
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Quoted:
^ The man's right, you know!
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Quoted:
Quoted:
In my experience you will run into mag length issues before you are able to get very close to the lands in an AR-15 style rifle...
^ The man's right, you know!
Depends on the chamber.

In my Krieger barreled rifle, 77 grain Sierra Matchkings at mag length are .020 off the lands.
SMKs aren't jump sensitive so it isn't a make-or-break deal, but closer is better
Link Posted: 9/11/2017 10:34:40 PM EDT
[#8]
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Quoted:


No sure if you're alluding to .223 or 300blk. Even with .05 extra, most .233 loads won't be into the lands. With 300blk, certain bullets can be into the lands at much less than mag length.
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Quoted:


No sure if you're alluding to .223 or 300blk. Even with .05 extra, most .233 loads won't be into the lands. With 300blk, certain bullets can be into the lands at much less than mag length.
That is the case for all ASC mags, or at least their mags for .223, 6.5G, 6.5C and 308. 50 thou, based on your chamber, could be 50% or more closer to the lands so I'd consider that significant.

Quoted:


Depends on the chamber.

In my Krieger barreled rifle, 77 grain Sierra Matchkings at mag length are .020 off the lands.
SMKs aren't jump sensitive so it isn't a make-or-break deal, but closer is better
Good to know. How does it shoot?
Link Posted: 9/11/2017 10:39:25 PM EDT
[#9]
For the ar platform, mag length

If I am going to worry about bullet position to the lands, I will build a bolt gun
Link Posted: 9/11/2017 10:46:06 PM EDT
[#10]
Link Posted: 9/11/2017 10:47:04 PM EDT
[#11]
You can single load...
Link Posted: 9/12/2017 1:37:01 AM EDT
[#12]
Using the split-neck method, a 77gr SMK usually soft seats to about 2.36", however most 5.56/Wylde reamers show about 0.060" long freebore and the leade is a little longer than that.

Unless single loading, load to 2.26", find a node with powder charge, then seat deeper in hopes groups shrink further.
Link Posted: 9/12/2017 5:16:30 AM EDT
[#13]
Reducing bullet jump can help but personally I think too much emphasis is put on it at times.

When you actually go though the sequence of events when the cartridge is fired the neck of the casing is probably the last thing to expand and by the time it does the bullet which starts moving with much less pressure has already slid forward to the lands while still being fully supported by neck tension.

I do measure zero jump length on just about everything I load and record it on my load card file. So when I get a chance I'll see if I can post some numbers for you.

They really don't do me any good in the AR-15 anyway because of the aforementioned magazine length limitations.

As far as accuracy goes I'm well pleased and wouldn't bother buying a magazine to gain .050"

Motor
Link Posted: 9/12/2017 5:23:08 AM EDT
[#14]
I work up .010" off the lands and leave it there.

This makes for:

.223
2.615" for 80eldm
2.585" for 90smk

6.5G
2.395" 147eldm
2.465" 140hyb
Link Posted: 9/12/2017 8:59:32 PM EDT
[#15]
White Oak National Match upper: Wylde chamber Krieger barrel
---To the lands with Hornady 75 gr. A-Max 2.420"------single load only                                                                                                                                                                                                      ------------Hornady 55 FMJ's to touch the lands in a Rock River and Colt 5.56---2.370" in one and 2.390" in the other.  Hornady 55 fmj's almost falling out of the neck at these lengths. Load to Hornady's recommended oal or out to 2.230"
---Sierra 77 Matchking to touch the lands---2.316". I load these at magazine length and better reliability at 2.255" rather than maximum of 2.260"
-----------Sierra 80 gr. Matchking to touch the lands 2.472". I load these to be .005" to .015" off the lands as per some recommendations for the 80 gr. Sie MK. These are single loaded.
 In my one bolt action Rem .223 Hornady 55 FMJ's touch the lands at 2.246". In my one 6.5 Grendel using only Hornady 123 A-Max I load to match Hornady's factory loads I've used. Oal to match Hornady's is 2.244" to 2.246". Feeds and shoots great at this oal.  Your rifles may differ and probably do from my WOA National Match AR.
Link Posted: 9/15/2017 1:41:52 PM EDT
[#16]
Link Posted: 9/15/2017 1:52:28 PM EDT
[#17]
I have some of the ASC .223 mags. The internal length is 2.316".

I played with COAL for my 77 gr. TMK load with 23.4 gr. IMR 8208xbr.

Cartridges were loaded at 2.290", 2.270", and 2.255". The standard mag length load was at least as accurate as the others, while also having the lowest SD and ES.
Link Posted: 9/15/2017 5:17:59 PM EDT
[#18]
Short less than 65 gr bullets will fall out of the case before reaching the lands.
Old rule of thumb.  You need on caliber of bearing surface in the case neck.  
Light wt bullets do not have all that much bearing surface to begin with.  
What is the point? None.


I have loads with TAC that have the 75/77gr OTM bullets being very accurate.  Not as accurate as say 75gr VLD Bergers, mind you.  But nice!

It is one thing for competitive reasons, but real life is a waste of time!
Link Posted: 9/17/2017 11:02:26 AM EDT
[#19]
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Quoted:
No sure if you're alluding to .223 or 300blk. Even with .05 extra, most .233 loads won't be into the lands. With 300blk, certain bullets can be into the lands at much less than mag length.
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Discussion ForumsJump to Quoted PostQuote History
Quoted:
Quoted:


Not with ASC mags. They give you a little over 50 thou more room:) I have them for all my AR's
No sure if you're alluding to .223 or 300blk. Even with .05 extra, most .233 loads won't be into the lands. With 300blk, certain bullets can be into the lands at much less than mag length.
Its not just about getting them closer to the lands, the bullets we are talking about are generally jump tolerant, loading them longer also reduces pressure ~3K PSI from 2.26 to 2.31 (Quickload)
Link Posted: 9/17/2017 12:16:49 PM EDT
[#20]
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Quoted:


Its not just about getting them closer to the lands, the bullets we are talking about are generally jump tolerant, loading them longer also reduces pressure ~3K PSI from 2.26 to 2.31 (Quickload)
View Quote
Not sure how this pertains to my post.

Very simply, most bullets loaded to mag length(regardless of brand), will not be into the lands on a standard chambered .223/5.56 AR. Never even bothered to check actual jump personally. Seems like a waste for mag fed shooting.
Link Posted: 9/17/2017 2:46:41 PM EDT
[#21]
It is just a reason 0.050" may matter in some situations.
Link Posted: 9/18/2017 1:08:29 AM EDT
[#22]
Quoted:
I am digging deeper into the never-ending-precision-ammo-making-techniques.
View Quote


With an AR-15?

If you have an AR-15 with a 5.56 chamber, you are not going to get anywhere close "to the lands" with any round that will fit in the magazine.  

If you have an "off the rack" AR-15, "chasing the lands" is ultimately going to be an exercise in futility.  If you want the precision that comes from loading ammunition just off the lands, get a bolt action rifle chambered in .223 Remington.  And then work on becoming part of the "five shots, one hole" fraternity.  Otherwise, load the cartridges to the OAL specified in the manual and go out to the range and have fun.
Link Posted: 9/18/2017 1:16:22 PM EDT
[#23]
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Quoted:
I have some of the ASC .223 mags. The internal length is 2.316".

I played with COAL for my 77 gr. TMK load with 23.4 gr. IMR 8208xbr.

Cartridges were loaded at 2.290", 2.270", and 2.255". The standard mag length load was at least as accurate as the others, while also having the lowest SD and ES.
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Quoted:
I have some of the ASC .223 mags. The internal length is 2.316".

I played with COAL for my 77 gr. TMK load with 23.4 gr. IMR 8208xbr.

Cartridges were loaded at 2.290", 2.270", and 2.255". The standard mag length load was at least as accurate as the others, while also having the lowest SD and ES.
Interesting, have you tried testing with any other bullets?


Quoted:


Its not just about getting them closer to the lands, the bullets we are talking about are generally jump tolerant, loading them longer also reduces pressure ~3K PSI from 2.26 to 2.31 (Quickload)
Really? I thought pressures go up when the bullets were closer?

Quoted:
With an AR-15?

If you have an AR-15 with a 5.56 chamber, you are not going to get anywhere close "to the lands" with any round that will fit in the magazine.  

If you have an "off the rack" AR-15, "chasing the lands" is ultimately going to be an exercise in futility.  If you want the precision that comes from loading ammunition just off the lands, get a bolt action rifle chambered in .223 Remington.  And then work on becoming part of the "five shots, one hole" fraternity.  Otherwise, load the cartridges to the OAL specified in the manual and go out to the range and have fun.
I don't think guys would come here and make this thread if they had rack grade AR's. I've shot in the .3's with my AR and am just trying to see if it can get better. I've measured my chamber and distance to the lands and believe I can get pretty close. My comparator just came in so I'm going to see exactly how far off the pet loads are. I'm one of those weirdos that likes to shoot my AR @1000 yards and have pretty good success. If I can get another .1moa out of seating depth my average hit ratio will go up.

What I didn't tell anyone is the whole goal for this is 75% or higher hit ratio @1000. I'm at about 40% right now on a 1.5moa plate. Also still haven't got a cold bore hit @1000 yet either
Link Posted: 9/18/2017 4:47:31 PM EDT
[#24]
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Quoted:


Interesting, have you tried testing with any other bullets?




Really? I thought pressures go up when the bullets were closer?



I don't think guys would come here and make this thread if they had rack grade AR's. I've shot in the .3's with my AR and am just trying to see if it can get better. I've measured my chamber and distance to the lands and believe I can get pretty close. My comparator just came in so I'm going to see exactly how far off the pet loads are. I'm one of those weirdos that likes to shoot my AR @1000 yards and have pretty good success. If I can get another .1moa out of seating depth my average hit ratio will go up.

What I didn't tell anyone is the whole goal for this is 75% or higher hit ratio @1000. I'm at about 40% right now on a 1.5moa plate. Also still haven't got a cold bore hit @1000 yet either
View Quote
Moving the bullet out with a given powder charge increases empty case volume which reduces pressure.

Develop a near max load at .030" off the lands, then move the bullet out to the lands with that charge weight you will likely see a pressure increase from the proximity to the lands.



.1-.2moa smaller groups won't do shit at 1k. Higher BC bullets and/or lower SDs/ESs and/or better wind reading will do more for you than small increases in precision.

If you want 75% at 1k you better just use a 4moa plate.





Lets assume you are an expert wind reader(to 1mph) and nail the atmospherics perfectly and your load is .2moa(it won't be) and every bullet has the exact same BC( they won't).

My 147eldm 24" 6.5grendel load(2435fps) has the highest hit % over all other weights 72%

Same but in .223 with a 90gr VLD @2700fps(24" velocity) 68% hits on 1.5x1.5moa plate

Same but in .223 with a 80gr eldm @2850fps(24" velocity) 69% hits on 1.5x1.5moa plate







Now I will leave everything but the precision, I will put that at 1moa instead of .2moa.

My 147eldm 24" 6.5grendel load(2435fps)  67%

Same but in .223 with a 90gr VLD @2700fps(24" velocity) 64% hits on 1.5x1.5moa plate

Same but in .223 with a 80gr eldm @2850fps(24" velocity) 65% hits on 1.5x1.5moa plate

So you can see going from 1moa to .2moa only gives you a few % increase in hits at 1K. If you are at 40% now getting your precision into the zeros won't help much.
Link Posted: 9/18/2017 10:22:38 PM EDT
[#25]
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Quoted:
That is the case for all ASC mags, or at least their mags for .223, 6.5G, 6.5C and 308. 50 thou, based on your chamber, could be 50% or more closer to the lands so I'd consider that significant.

Good to know. How does it shoot?
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Quoted:
Quoted:


No sure if you're alluding to .223 or 300blk. Even with .05 extra, most .233 loads won't be into the lands. With 300blk, certain bullets can be into the lands at much less than mag length.
That is the case for all ASC mags, or at least their mags for .223, 6.5G, 6.5C and 308. 50 thou, based on your chamber, could be 50% or more closer to the lands so I'd consider that significant.

Quoted:


Depends on the chamber.

In my Krieger barreled rifle, 77 grain Sierra Matchkings at mag length are .020 off the lands.
SMKs aren't jump sensitive so it isn't a make-or-break deal, but closer is better
Good to know. How does it shoot?
It runs in the 0.7-ish range.
Better than I'd hoped or expected for an autolader, especially with just a forged upper.
Link Posted: 9/19/2017 8:12:49 PM EDT
[#26]
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Quoted:
Moving the bullet out with a given powder charge increases empty case volume which reduces pressure.

Develop a near max load at .030" off the lands, then move the bullet out to the lands with that charge weight you will likely see a pressure increase from the proximity to the lands.

So you can see going from 1moa to .2moa only gives you a few % increase in hits at 1K. If you are at 40% now getting your precision into the zeros won't help much.
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Discussion ForumsJump to Quoted PostQuote History
Quoted:
Moving the bullet out with a given powder charge increases empty case volume which reduces pressure.

Develop a near max load at .030" off the lands, then move the bullet out to the lands with that charge weight you will likely see a pressure increase from the proximity to the lands.

So you can see going from 1moa to .2moa only gives you a few % increase in hits at 1K. If you are at 40% now getting your precision into the zeros won't help much.
Thanks for the info.

Quoted:


It runs in the 0.7-ish range.
Better than I'd hoped or expected for an autolader, especially with just a forged upper.
Yeah it's pretty hard to make them work perfectly every round.

So I went to the range yesterday and tried some different depths. At normal mag-length I am .073 off the lands. I seated .007" closer to the lands on 4 different groups and the last group I seated .010 off the lands or .063 deeper than mag length. The very first and last group were my control groups aka standard pet/mag length load.

It was 100 degrees outside so I am sure that didn't help. I was shooting fast and not really allowing for barrel to cool so it is what it is. Also a few of these I pulled so shooter certainly isn't perfect and needs work too.

The groups read like a book in that order.
The 2 holes on this page with lines next to them were me fouling and sighting in scope. I did this on a freshly cleaned and copper removed bore.



Rig
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