AR 308 260 Rem blowing out primer pockets

[krh625]

I am new to the forum and hit a road block with my new build. 

I have searched the internet extensively and read several threads but none seem to address my current issue.  I built a AR-308 in a 260 Rem.  The issue I am having is that I loose about 25% of my factory brass to swelled primer pockets and the others last one reload.  I have 2-300 rounds through the gun.  I didn't notice this issue with I first started to break in the barrel and initial load development.   

Its is configured as such -

Aero Precision M5 Receivers

Brownell BCG and bolt with small firing pin 

Wilson Combat 24 inch barrel with rifle length gas system

Wilson Combat M2 - 2 stage trigger

Superlative adjustable gas block

Stoner 9 oz buffer (Recently replace 5.4 oz buffer)

Factory loads are Federal Premium 140 gr Trophy Bonded Bear Claws (Factory Seconds)

I have a bolt action 260 Rem and the factory ammo shows no signs of pressure.  I checked the head space when the gun was assemble and re-checked recently.  I had read that it could be from bolt starting to open too soon and that is why I put in the heavier buffer.  Last weekend I shot it to adjust the gas block for the heavier buffer. Pressure signs on the brass weren't as noticeable with hardly any ejector mark. The brass I lost could have been from when I was adjusting the block. Once it was set I shot 3 - 3 shot groups with my hand loads and tossed all 9 brass.  The hand load is 45.4 gr R22 with 140 gr Nosler RDF. This load is on the higher end for R22 but I didn't have any issues during the load development.   Any thoughts or suggestions would be very helpful. 

Thanks

 

[Armed Eye Doc]

Do you have pictures of the brass, both the damaged and undamaged ones for comparison?  What receiver extension (buffer tube) do you have and what is the internal depth?  What spring are you using?

[jtallen83]

Yep, pictures are a must, get the bolt face as well as the brass. Have you cycled through loaded rounds to see if your getting any bullet setback? Headspace would have been my first question, what brand gauges did you use? I have that same barrel sitting in a parts box so I'll be following along here for sure.

and Welcome From Iowa!

[98Z5V]

13 hours ago, krh625 said:

The hand load is 45.4 gr R22 with 140 gr Nosler RDF. This load is on the higher end for R22 but I didn't have any issues during the load development.  

 

 

That's a fuckin' STOUT LOAD for a .260 Rem and RL-22.  That thing has to be just screamin'!.  Not to mention the extra 4" of dwell time that you have, over what I shoot.  What's your muzzle velocity out of that thing? 

[Magwa]

47 minutes ago, 98Z5V said:

That's a fuckin' STOUT LOAD for a .260 Rem and RL-22.  That thing has to be just screamin'!.  Not to mention the extra 4" of dwell time that you have, over what I shoot.  What's your muzzle velocity out of that thing? 

The load is to hot! you need to drop back till you get no brass malfunction or primer pocket issues what works in one gun may not work in another but that is a hot load..

[98Z5V]

read this thread, to get the scope - of the kinda detail that we need to "diagnose this over the internet..."   You stated the buffer weight change - but you never mentioned the receiver extension length, or what specific spring you're using.  That's just an example.

Same thing with gas system specs.  All we know is "rifle gas system on 24" WC barrel."  That's it.  No reference to what gas tube used, how far it protrudes into the upper, gas port diameter, etc.

Check it:

 

After checking that one out, just to kind of understand the level of detail needed - online - to figure out your gun... then read this one:

There's alot to shake out here - and WAY MORE information will be needed.

P.S.  Your .260 Rem load is hot as fuk.  Please get me that muzzle velocity.

[98Z5V]

2 minutes ago, Magwa said:

The load is to hot! you need to drop back till you get no brass malfunction or primer pocket issues what works in one gun may not work in another but that is a hot load..

Especially bolt-gun loads that you shoot in semi's...   I've got some bolt gun loads that are fine.  In a bolt.  If I shoot that shiit through the ARs - I'll have blown up AR guns. 

[98Z5V]

16 hours ago, krh625 said:

The hand load is 45.4 gr R22 with 140 gr Nosler RDF. This load is on the higher end for R22 but I didn't have any issues during the load development.   Any thoughts or suggestions would be very helpful.

I'll dump my .260 Rem load details here, but only after I hear your load details first.  I'm really curious about the details - especially your muzzle velocity - and how you came up with that powder load. I'm reloading with nothing but RL-22, since I built this gun 3-ish years ago - no other powder has ever touched this gun.   My MV is 2650fps from a 20" rifle-gas barrel, and it's a laser, for precision, and still supersonic to 1,500 yards on 17.2 mils of dial, and that's a 100-yard zero for dope.  My next goal for this gun is getting it to 1,760 yards, beyond that trans-sonic "shake", and see if I can repeatedly get it there.   

That 45.4gr charge of RL-22 is high as hell, especially for the dwell time of a 24" barrel that's rifle-gas.  That's alot of dwell time, and alot of time to dump that pressure into the BCG. Please spill the details.  Cases, primers, trim length, where you're getting the brass from, loaded COL, etc.  All the other details of the gun need to spill, too - all the ones that I referenced above.

This is workable.  We just need details.

EDIT - For clarification from my part - I only have one .260 Rem, and it's an AR.  I don't have any others, and no bolt guns in that caliber.  The only load development I've ever done on .260 Rem is all gas-gun load development. 

Edited March 9, 2021 by 98Z5V

[krh625]

Thanks for letting me the know the information that I need to post for more help.

As I mentioned I am running a 9 oz AR Stoner buffer with a AR Stoner LR 308 buffer spring in a rifle length buffer tube.

Head spacing gauge is Clymer 1.630 Go and 1.634 No Go.

I know the R22 hand load is hot.  Looking through my data I am getting 2750 psi with the RDF bullet and breaking 2800 fps with a 140 gr MatchKing. My goal is the get teh gun setup so I don't ruin the factory brass.  A t this time I don't have any pictures of primers or bolt face .  I started to reload the factory brass after I switched the buffer and spring to see if that helped.  It did help some since the bolt face doesn't have a ring of material from the outside of the primer on it now.  I had to readjust my gas block so that could have cause some pressure issues until it was set. Currently It is only 1.25 turns open. Hopefully I will get out this weekend and will be able to take more pictures.  

I have attached pictures of the gas tube length which is short.  

Thanks

 

 

[98Z5V]

13 hours ago, krh625 said:

Thanks for letting me the know the information that I need to post for more help.

As I mentioned I am running a 9 oz AR Stoner buffer with a AR Stoner LR 308 buffer spring in a rifle length buffer tube.

I know the R22 hand load is hot.  Looking through my data I am getting 2750 psi with the RDF bullet and breaking 2800 fps with a 140 gr MatchKing. My goal is the get teh gun setup so I don't ruin the factory brass.  A t this time I don't have any pictures of primers or bolt face .  I started to reload the factory brass after I switched the buffer and spring to see if that helped.  It did help some since the bolt face doesn't have a ring of material from the outside of the primer on it now.  I had to readjust my gas block so that could have cause some pressure issues until it was set. Currently It is only 1.25 turns open. Hopefully I will get out this weekend and will be able to take more pictures. 

You should be higher on that muzzle velocity, for that load - wouldn't matter which projectile, as both are 140s.  I punched in my load information to ShootersNotes Velocity Estimator, then added your info as the change.  You should be jamming those things pretty close to 2950fps.  Click it a few times, it gets bigger...

 

If it were mine, I'd verify the internal depth of the rifle receiver extension - it should be 9 11/16" internal depth.  Then, I'd change the spring to a known, quality spring, and that would be the Armalite EA1095 spring.  Buffer weight is good, as long as that buffer is 5.200" long.

The only brass is use for my load is Hornady .308 Win Match cases, resized for the .260 Rem, and all necks turned.  I check length after every firing, and bring them all to 2.035" if any went longer.  This just gives me a uniform crimp everytime, through a Lee Factory Crimp Die.  I load RL-22 at 43.0 grains, use CCI 200 primers, and use Hornady 147 ELD-M projectiles, loaded to 2.795" OAL.  This is giving me dead-on 2650 fps through a 20" rifle-gas Wilson Combat Tactical Hunter barrel.

That load you're running is very hot.  I'd back that thing down, and start over.  That short gas tube is leaving some gas timing on the table, that you could use, but with that load, I don't think it would matter if the gas tube were correct - that BCG has to be just MOVING... 

 

[98Z5V]

The only other things that I use RL-22 powder for are my .300 Win Mag loads, flinging 225gr ELD-Ms at 2932 fps through a Rem 700 26" heavy barrel, and in the .338 Lapua Magnum loads with the Hornady 285gr ELD-Ms.   

[krh625]

Today I was finally able to get out to the range.  I shot 3 shots with each of 140 gr factory, 140 gr MK and 140 gr RDF though a clean gun over my chrono.  The only change that I make was installing a Strike AR10 flat wire spring.  It had more recoil but the gas block did not need any adjusting.  I put the original spring back in when I got home. I did measure the depth of the buffer tube and it is correct.  Here are the pictures.

Federal Premium 140 gr Sierra Game King Avg velocity 2740 fps with chrono set 10 ft from muzzle.  

Reload with 45.4 gr RL22 and 140 gr Sierra Match King Avg Velocity 2810 fps

Reload with 45.4 gr RL22 and 140 gr Nosler RDF Avg Velocity 2710 fps 

The picture of the bolt face is after the 9 shots.  

[98Z5V]

1 hour ago, krh625 said:

 

 

 

Groups are great, but you've got some pretty heavy primer cratering going on.  Ejector smears are visible - they'd be alot worse if that was a square-faced ejector, so be glad that it's a round one.  You're still way up there on the load, looking at that brass.  Doesn't mean anything, but if it was mine, I'd go in 0.2gr increments, and back that thing down to the next accuracy node, and stay there.  What's you're COL on those? 

P.S  I hate Federal brass, unless it's Gold Medal Match brass.  All other (standard) Fed brass work-hardens pretty quick.