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Posted: 8/10/2020 4:53:42 PM EDT
[Last Edit: 9/5/2020 8:46:12 PM EDT by gman556]
I installed a new Rainier Arms Ultramatch MOD2 18" Barrel on my DPMS gen ll 308 about a month ago.

Gas block is .800 size.

Everything started out fine for the break-in with some factory loads and a few of my mild hand loads.

I got to about 80 rounds through it and started getting stuck cases with just my reloads. I figured I must be under sizing or she could be over gassed. First I made sure that my hand loads were sized down properly and fit the case gauge and chamber of the barrel. Second I ordered an adjustable bleed off gas block from Rainier that is made by SLR I believe.

I've been using IMR 4895 and I thought maybe this powder was burning a little too quick so I switched to Varget and proceeded to work some loads up for it this past weekend and just about every other case stuck in the chamber and had to be tapped out with a cleaning rod.

When this happens it looks like a typical overpressure load with the rim torn off by the extractor and the case stuck in the chamber. The primers on these cases even looked like they were a little flat. This was with the starting charge so I didn't even get a chance to test all the loads and was only able to fire about four rounds after giving up and packing in due to being cautious.


I have cleaned the chamber and barrel after each range session so I think I can rule out a dirty chamber.

I'm using an RCBS Chargemaster combo and I'm wondering if this thing could be that far off and overcharging? The loads did not feel like they were hot when firing and after inspecting the chamber it didn't seem rough, but so far to start diagnosing the problem I did polish it with flitz.

Brass is LC,PPU and FC.

Last session I adjusted the gas block all the way out to the bleed off point than 20 clicks in, cases were ejecting at 4 o'clock and  the factory loads still did not feel like they were hot when shooting but yet I'm still getting stuck cases.

I'm stumped here and would appreciate any suggestions.

Could it be a headspace issue? I'm going to get out my gauges and check that tonight.
Link Posted: 8/10/2020 5:07:15 PM EDT
[Last Edit: 8/10/2020 5:08:24 PM EDT by lokifox]
The Rainier barrels have has issues in the past. I would take a good look at it.

Inspect a fired case for signs of a burr in the chamber.

Up your buffer weight. Seriously that’s step one. The GII rifle bolts are too light in my opinion. The bleed off is a gimmick IMO. It adds more complexity to the equation.

In an autoloader, your max load could be what the load data lists as a starting load. With Varget it’s basically impossible to overcharge enough to cause problems, but then again - autoloader. 42-43gr. with a 168 will likely start showing pressure. Again buffer weight will help. I’m running a 11.6 oz. buffer in my G2 243. It’s not an apples to apples comparison, but it is important.
Link Posted: 8/10/2020 5:23:08 PM EDT
[Last Edit: 8/10/2020 5:26:30 PM EDT by gman556]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By lokifox:
The Rainier barrels have has issues in the past. I would take a good look at it.

Inspect a fired case for signs of a burr in the chamber.

Up your buffer weight. Seriously that’s step one. The GII rifle bolts are too light in my opinion. The bleed off is a gimmick IMO. It adds more complexity to the equation.

In an autoloader, your max load could be what the load data lists as a starting load. With Varget it’s basically impossible to overcharge enough to cause problems, but then again - autoloader. 42-43gr. with a 168 will likely start showing pressure. Again buffer weight will help. I’m running a 11.6 oz. buffer in my G2 243. It’s not an apples to apples comparison, but it is important.
View Quote


Forgot to ad add that I upped my buffer weight to 6.4 from 5.4 and added another tungsten weight to bring it up too 7.4.

I did try an 11.6 from heavy buffers with the Original factory barrel, and it didn't seem to dampen the recoil a bit but the casings were coming right straight back over my shoulder to almost 530 6 o'clock, maybe not a big deal? I was thinking a try and that buffer again next time around.

Yes the BCG does seem a bit light for an AR 10 on the G2

It does seem like the stuck cases started once I installed the adjustable gas block. Unfortunately I can't remember for sure though. Man I wish I wrote this crap down I was thinking of putting the regular gas block back on and just going with a heavier buffer next time, not sure?

Forgot to add also that it is an intermediate 18 inch barreled gas system with a .85 size gas port.
Link Posted: 8/10/2020 5:55:34 PM EDT
I've yet to get my Rainer arms 6.5 creedmore barrel to be relieble.
Link Posted: 8/10/2020 6:22:40 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By jbirdious:
I've yet to get my Rainer arms 6.5 creedmore barrel to be relieble.
View Quote


That's not good

Was thinking of ordering a Craddock Precision barrel but not sure I want to spend almost $600 and have the same issues as with the Rainier.

Dumba@#@ that I am I had to have a "Match" barrel

I got so bumbed out about it the other day that I sold off all my spare Gen ll parts. I am having second thoughts and regrets so I was really hoping it was my handloads, hence why I posted in this forum.

Link Posted: 8/10/2020 6:34:47 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By gman556:


That's not good

Was thinking of ordering a Craddock Precision barrel but not sure I want to spend almost $600 and have the same issues as with the Rainier.

Dumba@#@ that I am I had to have a "Match" barrel

I got so bumbed out about it the other day that I sold off all my spare Gen ll parts. I am having second thoughts and regrets so I was really hoping it was my handloads, hence why I posted in this forum.

View Quote View All Quotes
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Discussion ForumsJump to Quoted PostQuote History
Originally Posted By gman556:
Originally Posted By jbirdious:
I've yet to get my Rainer arms 6.5 creedmore barrel to be relieble.


That's not good

Was thinking of ordering a Craddock Precision barrel but not sure I want to spend almost $600 and have the same issues as with the Rainier.

Dumba@#@ that I am I had to have a "Match" barrel

I got so bumbed out about it the other day that I sold off all my spare Gen ll parts. I am having second thoughts and regrets so I was really hoping it was my handloads, hence why I posted in this forum.



Order a couple of the 20" 260 barrels from CDNN. $80 a piece.

The 243 barrel of mine from the same pile of parts is a legitimate 1/4 MOA shooter. $80... I would do a 260 if I didn't mind undertaking another cartridge and the associated logistics.
Link Posted: 8/10/2020 8:13:13 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By lokifox:


Order a couple of the 20" 260 barrels from CDNN. $80 a piece.

The 243 barrel of mine from the same pile of parts is a legitimate 1/4 MOA shooter. $80... I would do a 260 if I didn't mind undertaking another cartridge and the associated logistics.
View Quote



Now you got me thinking.

I would only have to get the dies I believe for the 260 rem. Mags and bolt should work?

Link Posted: 8/10/2020 8:21:00 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By gman556:



Now you got me thinking.

I would only have to get the dies I believe for the 260 rem. Mags and bolt should work?

View Quote View All Quotes
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Discussion ForumsJump to Quoted PostQuote History
Originally Posted By gman556:
Originally Posted By lokifox:


Order a couple of the 20" 260 barrels from CDNN. $80 a piece.

The 243 barrel of mine from the same pile of parts is a legitimate 1/4 MOA shooter. $80... I would do a 260 if I didn't mind undertaking another cartridge and the associated logistics.



Now you got me thinking.

I would only have to get the dies I believe for the 260 rem. Mags and bolt should work?



Yep. Barrel is your only needed part.

We're way off topic here but whatever!

You will absolutely want a bunch of buffer weight the more overbore you go. 260 shouldn't be too bad but the 6mm's are tough to tame.

I don't know what the freebore looks like in the 260 barrels, but I can hit the lands with a couple traditional HPBT's in the 243. The twist is a bit too slow for the more modern 100+ gr. 6mm bullets. I believe the 260's are 1/8 so they should be pretty versatile.... I may have to order a couple. Shoot...

The only "real" issue is that 260 ammo/brass is pretty pricey compared to 308 and now 6.5. Starline brass has been exceptional in my 243. I'm going on 7 (maximum charge) loads on one batch without annealing - which from what I've been told is some sort of miracle due to some eccentricities of the 243 Win.
Link Posted: 8/10/2020 8:39:17 PM EDT
[Last Edit: 8/10/2020 8:42:07 PM EDT by gman556]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By lokifox:


Yep. Barrel is your only needed part.

We're way off topic here but whatever!

You will absolutely want a bunch of buffer weight the more overbore you go. 260 shouldn't be too bad but the 6mm's are tough to tame.

I don't know what the freebore looks like in the 260 barrels, but I can hit the lands with a couple traditional HPBT's in the 243. The twist is a bit too slow for the more modern 100+ gr. 6mm bullets. I believe the 260's are 1/8 so they should be pretty versatile.... I may have to order a couple. Shoot...

The only "real" issue is that 260 ammo/brass is pretty pricey compared to 308 and now 6.5. Starline brass has been exceptional in my 243. I'm going on 7 (maximum charge) loads on one batch without annealing - which from what I've been told is some sort of miracle due to some eccentricities of the 243 Win.
View Quote



Thanks for that great info, and to get back on track still wondering if it might also have something to do with my hand loads?

I can't recall 100% but I could've swore that This started happening with my hand loads.

At first I thought maybe I was not sizing them down enough because I was sizing them .003– .004 from the Rainier chamber fired brass.

The next time I sized them down about .008 and the dropped right in the case gauge and the chamber of the Rainier barrel fine.
I also thought maybe being that IMR 4895 was a little faster burning powder then say Varget I would try the latter this time.

Worked up some loads with some 175 grain SMK's from bottom charge on the Hodgdon website In five rounds increments all the way up to the top charge.

All I got was the first four rounds from the start charge and two out of the four got stuck in the chamber. I thought hmmm, maybe my RCBS charge master is over or something so I have a set of check weights on the way, but shooting those first four starting loads did not feel like they were hot or anything.

Link Posted: 8/11/2020 9:31:10 AM EDT
Go back to square one and try some factory rounds through it to establish a new base line. If no issues with factory, check your case and OAL against factory.

If factory has the same issues, put the original gas block on.  If still issues, send the barrel back.
Link Posted: 8/11/2020 9:56:29 AM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Mounger:
Go back to square one and try some factory rounds through it to establish a new base line. If no issues with factory, check your case and OAL against factory.

If factory has the same issues, put the original gas block on.  If still issues, send the barrel back.
View Quote


Amen brother going to try some factory this weekend and put their non-adjustable GB back on last night.

Going to check my HL’s against factory tonight again. Did it last time and I remember everything being ok but not 100% sure so double check again  

Link Posted: 8/11/2020 10:06:03 AM EDT
Looking forward to you getting this figured out.  I’m curious.
Link Posted: 8/11/2020 10:57:31 AM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Mounger:
Looking forward to you getting this figured out.  I’m curious.
View Quote


Me too. Want to get to the bottom of this. Really like the Gen 2 platform and was looking forward to getting my handloads dialed in for it.
Link Posted: 8/11/2020 3:48:24 PM EDT
Just got home and measured my sized casses with some factory ammo and my sized cases were .004-005 smaller than the factory cases.

Looks like I can rule out undersized?

If I get out to put some factory ammo through this weekend and it functions fine, what else could be wrong with my handloads here?

Iv'e loaded for my 308  bolt gun and my M1A before and never experienced this.

If it's not my HL's than I'm going to chalk it up to the Rainier barrel.

I bought two of them in the same config as above and I guess I could try the unused second one or just send them both back.
Link Posted: 8/16/2020 5:51:34 PM EDT
[Last Edit: 8/16/2020 6:08:33 PM EDT by gman556]
Had the rifle completely apart during the week and polished the chamber, put the regular gas block back on and went with a heavy buffer from heavy buffers.com and spring.

ETA: Also forgot to mention I checked headspace with Forster 7.62 gauges and it closed on the MIN and wouldn't close on the MAX.

Bought a box of the crappiest  ammo I could find which was Tula 308 150 grain FMJ, and bring along my hand loads to test again.

Fired one 20 round box of the crappy Tula and it ran flawlessly.

Cases were ejecting at about 3 o'clock to 330.

I had about 50 175 grain test loads still from my last range session. All in five round groups from lowest charge to Max as per Hodgdon.

I made it through 45 of those and when I got to the last 5 rounds one immediately stuck in the chamber again so I packed up and bring it home disappointed.

I'm thinking it's got a be something to do with my hand loads?

So that's pretty much where I am at right now, still stumped.

Not sure what I'm going to try next at this point except for maybe making another range trip and trying to fire just exclusively factory ammo and see what happens with that. I have to admit I'm getting a little burnt out on this project and may end up just sending the barrel back to Rainier, then getting a factory DPMS barrel I saw here on the equipment exchange and trade this puppy in on a bolt gun.

@dryflash3 If you think this thread doesn't belong here than please feel free to move it.
Link Posted: 8/16/2020 6:17:58 PM EDT
@gman556

I have a couple of DPMS 308's, and have been loading 308 pretty much since I started reloading.  

Your brass is your first (smaller) problem.  Sell the FC brass, then work up your loads in one brand of brass either the LC or the PPU, whichever you have the most of.  If everything else is EXACTLY equal, expect the LC loads to be a bit hotter by a small but measurable margin.  If you are running close to max loads, work up in the LC.  

Your powder is your second (bigger) problem.  Switch to a spherical (ball) powder like H380, BL-C(2) or RL15.  I love Varget in a bolt gun, but have had nothing but trouble with it in gas guns - especially if they were already fineky.  Also, try not to ride the upper edge of the range (min to max).  Feel free to PM me with other questions.
Link Posted: 8/16/2020 6:47:01 PM EDT
[Last Edit: 8/16/2020 6:49:33 PM EDT by lokifox]
Ok...

First, firing brass cased ammo after steel cased is a REALLY good way to ensure you get a stuck case. You introduce particulates to the chamber wall when shooting the steel cases, then the brass locks itself to the particulates. It's not an internet myth - definitely a real thing.

Second, if you were at Hodgdon max with an autoloader it is likely you are beyond what your rifle can handle without adding buffer weight. Remember, the rifles are designed to run with a wide gamut of ammo.

Two questions.

1 - What is your buffer weight? ETA - If it's still 7.4 you may need to go even higher. The G2 BCG weighs significantly less than a full sized rifle. They will run at minimum weight but they typically need to be tuned to your specific load in my experience.

2 - Are you running a suppressor?
Link Posted: 8/16/2020 7:27:29 PM EDT
1.  Did you measure and trim your cases after sizing?

2.  How much shoulder set back do your reloads have?

3.  Shut off the gas completely and see if you still have stuck cases and high pressure signs.

3.  Let in only enough to operate the rifle, starting with it shut off.
Link Posted: 8/16/2020 7:50:30 PM EDT
[Last Edit: 8/16/2020 7:52:28 PM EDT by gman556]
Thanks everyone.

Brass was LC trimmed to 2008. I believe 2015 is the max? 2005 is min trim length?

Buffer weight was 10.5 oz.

Cases were ejecting at 3-3:30.

Adjustable GB was replaced with a standard GB this time.

Barrel is an "18 with intermediate length gas and .85 gas port/ Rainier proprietary .800 GB DIA.

At first shoulder set back was .004-005 when I was having this issue the first time. After that I set them back .008-009

I forgot about the Steel case vs brass cases deal, so maybe that was a factor? I did get through 45 rds before the stuck case which was book max. Maybe too much? The first time this happened there were no steel cases fired beforehand.

My best accuracy was just past mid charge anyway.

Powder used so far was IMR4895 and Varget. I switched to the Varget because I figured being it is a slower burrner than IMR4895 it would decrease some pressure?  

Link Posted: 8/16/2020 11:45:52 PM EDT
Link Posted: 8/17/2020 12:06:10 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By dryflash3:
I had a feeling this would evolve into a reloading thread, for once I guessed right.

Keep going OP.
View Quote



Sounds good, thanks dryflash

Forgot to mention the brass from the last two sessions is on it's 3rd firing. I'm not going to be going any further than that with this brass.

Took some home after the last firing which was just before my OP and ran a paperclip inside the cases and found some to have the ridge inside them.

I'm wondering if I need to get a hundred or a couple hundred more factory rds through this barrel before I work up anymore handloads for it? I think this will also give me a good idea if it is my handloads. I'm thinking if I get any stuck cases with factory than there is a problem with this setup.

I have 215 rds on this barrel now.



Link Posted: 8/17/2020 10:40:47 PM EDT
[Last Edit: 8/17/2020 10:46:09 PM EDT by limaxray]
Are you using small-based dies, or regular ones?

I had the same problem, same difference in sizes between reloads and factory, turns out it the chamber was about as small as SAAMI specs allowed. Turned out my chamber is about .00000000000000000001" bigger than SAAMI specs, regular dies just weren't resizing them small enough to chamber.  

I bought small-based dies and my problems went away.

ETA:  Using a case-length gauge won't show this problem, because all it'll really tell you is if the headspace is correct. My understanding is the gauges are cut to SAAMI max sizes, not  minimum, so it won't tell you if the brass will fit in YOUR chamber, just in the sloppiest one that's still in spec.
Link Posted: 8/18/2020 8:34:33 AM EDT
[Last Edit: 8/18/2020 10:34:30 AM EDT by gman556]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By limaxray:
Are you using small-based dies, or regular ones?

I had the same problem, same difference in sizes between reloads and factory, turns out it the chamber was about as small as SAAMI specs allowed. Turned out my chamber is about .00000000000000000001" bigger than SAAMI specs, regular dies just weren't resizing them small enough to chamber.  

I bought small-based dies and my problems went away.

ETA:  Using a case-length gauge won't show this problem, because all it'll really tell you is if the headspace is correct. My understanding is the gauges are cut to SAAMI max sizes, not  minimum, so it won't tell you if the brass will fit in YOUR chamber, just in the sloppiest one that's still in spec.
View Quote



I was thinking the same thing myself, but some of these cases were fired from this barrel and using my Lock-N-Load Headspace Comparator I was bringing the neck back down to .005 than to .009 after the first trip.

My case guages are Dillion and have the step on the top. The sized cases were dropping below the steps also. I also tested them in the chamber and they dropped right in.

My die's are Redding and worked with all my other 308's, even my M1A. I wonder if I'm going to need a SB die just for this rifle?

How much could the brass be springing back I wonder?

I believe Dillon 308 dies are equal to small base or should I try RCBS being they actually do a SB die?

Anyways the barrel is going to be on it's way back to Rainier and I have a Brand new spare I'm going to try, but I may wait until I get a SM die first for that barrel.

ETA: Just ordered a Redding SB FL die.
I may consider keeping the barrel that is on it now because I'm really curious to see what happenns with it once I fire another 100 factory rds through it and try just sizing those with the SB die.

I think I'm also going to throw the adjustable GB back on it and not use the bleed off option and just the close off option next time.

Even though this project is burning me out on it somewhat it's eating away at me to get these reloads running right.
Link Posted: 8/18/2020 12:49:48 PM EDT
It's not the necks that are out of tolerance, it's the base, just up from the extractor groove. SBDs will resize the case body all the way to the extractor groove to minimum specs, to fit in tight chambers.

Downside is it does work the brass a lot, so you'll only get three or four reloads out of them anyway.  But they will extract like they're supposed to.  
Link Posted: 8/18/2020 3:07:24 PM EDT
[Last Edit: 8/18/2020 3:11:50 PM EDT by Wirebrush]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By gman556:


Forgot to ad add that I upped my buffer weight to 6.4 from 5.4 and added another tungsten weight to bring it up too 7.4.

I did try an 11.6 from heavy buffers with the Original factory barrel, and it didn't seem to dampen the recoil a bit but the casings were coming right straight back over my shoulder to almost 530 6 o'clock, maybe not a big deal? I was thinking a try and that buffer again next time around.

Yes the BCG does seem a bit light for an AR 10 on the G2

It does seem like the stuck cases started once I installed the adjustable gas block. Unfortunately I can't remember for sure though. Man I wish I wrote this crap down I was thinking of putting the regular gas block back on and just going with a heavier buffer next time, not sure?

Forgot to add also that it is an intermediate 18 inch barreled gas system with a .85 size gas port.
View Quote View All Quotes
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Discussion ForumsJump to Quoted PostQuote History
Originally Posted By gman556:
Originally Posted By lokifox:
The Rainier barrels have has issues in the past. I would take a good look at it.

Inspect a fired case for signs of a burr in the chamber.

Up your buffer weight. Seriously that’s step one. The GII rifle bolts are too light in my opinion. The bleed off is a gimmick IMO. It adds more complexity to the equation.

In an autoloader, your max load could be what the load data lists as a starting load. With Varget it’s basically impossible to overcharge enough to cause problems, but then again - autoloader. 42-43gr. with a 168 will likely start showing pressure. Again buffer weight will help. I’m running a 11.6 oz. buffer in my G2 243. It’s not an apples to apples comparison, but it is important.


Forgot to ad add that I upped my buffer weight to 6.4 from 5.4 and added another tungsten weight to bring it up too 7.4.

I did try an 11.6 from heavy buffers with the Original factory barrel, and it didn't seem to dampen the recoil a bit but the casings were coming right straight back over my shoulder to almost 530 6 o'clock, maybe not a big deal? I was thinking a try and that buffer again next time around.

Yes the BCG does seem a bit light for an AR 10 on the G2

It does seem like the stuck cases started once I installed the adjustable gas block. Unfortunately I can't remember for sure though. Man I wish I wrote this crap down I was thinking of putting the regular gas block back on and just going with a heavier buffer next time, not sure?

Forgot to add also that it is an intermediate 18 inch barreled gas system with a .85 size gas port.


Intermediate gas system is a big part of the problem IMHO.  I've seen the same issue with a friend's Seekins 308 with the intermediate gas system.  I would get rid of that barrel and get one with a rifle length gas system (or longer).  The short gas system is trying to extract the case before chamber pressure drops enough.

ETA- my most recent 308 AR build I used a +2 gas system and it has run perfectly with 110 up to 178s all loaded quite hot.
Link Posted: 8/18/2020 3:34:29 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By limaxray:
It's not the necks that are out of tolerance, it's the base, just up from the extractor groove. SBDs will resize the case body all the way to the extractor groove to minimum specs, to fit in tight chambers.

Downside is it does work the brass a lot, so you'll only get three or four reloads out of them anyway.  But they will extract like they're supposed to.  
View Quote


Yes I just measured the base of the few cases I have left that I haven't charged yet and they are at .470 which is I believe the spec, so I'm wondering if the SB die will size them down .001 or 2 from there?

If this is the case it still doesn't explain why quite a few of the other rds functioned with no sticking when their base measures the same .470? Maybe just got lucky and there was some voodoo going on here?

As far as working the brass more it won't bother me because I usually only reload 308 gas gun brass 3-4 times and chuck them.
Link Posted: 8/18/2020 5:18:14 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Wirebrush:


Intermediate gas system is a big part of the problem IMHO.  I've seen the same issue with a friend's Seekins 308 with the intermediate gas system.  I would get rid of that barrel and get one with a rifle length gas system (or longer).  The short gas system is trying to extract the case before chamber pressure drops enough.

ETA- my most recent 308 AR build I used a +2 gas system and it has run perfectly with 110 up to 178s all loaded quite hot.
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Originally Posted By Wirebrush:
Originally Posted By gman556:
Originally Posted By lokifox:
The Rainier barrels have has issues in the past. I would take a good look at it.

Inspect a fired case for signs of a burr in the chamber.

Up your buffer weight. Seriously that’s step one. The GII rifle bolts are too light in my opinion. The bleed off is a gimmick IMO. It adds more complexity to the equation.

In an autoloader, your max load could be what the load data lists as a starting load. With Varget it’s basically impossible to overcharge enough to cause problems, but then again - autoloader. 42-43gr. with a 168 will likely start showing pressure. Again buffer weight will help. I’m running a 11.6 oz. buffer in my G2 243. It’s not an apples to apples comparison, but it is important.


Forgot to ad add that I upped my buffer weight to 6.4 from 5.4 and added another tungsten weight to bring it up too 7.4.

I did try an 11.6 from heavy buffers with the Original factory barrel, and it didn't seem to dampen the recoil a bit but the casings were coming right straight back over my shoulder to almost 530 6 o'clock, maybe not a big deal? I was thinking a try and that buffer again next time around.

Yes the BCG does seem a bit light for an AR 10 on the G2

It does seem like the stuck cases started once I installed the adjustable gas block. Unfortunately I can't remember for sure though. Man I wish I wrote this crap down I was thinking of putting the regular gas block back on and just going with a heavier buffer next time, not sure?

Forgot to add also that it is an intermediate 18 inch barreled gas system with a .85 size gas port.


Intermediate gas system is a big part of the problem IMHO.  I've seen the same issue with a friend's Seekins 308 with the intermediate gas system.  I would get rid of that barrel and get one with a rifle length gas system (or longer).  The short gas system is trying to extract the case before chamber pressure drops enough.

ETA- my most recent 308 AR build I used a +2 gas system and it has run perfectly with 110 up to 178s all loaded quite hot.


There's nothing inherently wrong with an intermediate gas system, but certain load combinations, barrel lengths, and cartridges are better suited to longer systems.

A 16" unsuppressed 308 barrel with a mid-length gas port is a very reliable setup across a wide variety of conditions.
Link Posted: 8/22/2020 2:42:34 PM EDT
The bolt unlocking too early can cause failure to extract issues and ejector marks even without excess pressures. I'd try adding an extra heavy buffer, I've had a midlength that just wouldn't run right regardless of spring and gas settings until I got a heavier carrier and buffer. The heavier buffer/carrier actually took the same to less gas to cycle (load dependent) which I attribute to the lighter system unlocking early when pressures are still high and the case is still hot/expanded in chamber.
Link Posted: 8/23/2020 9:03:58 PM EDT
[Last Edit: 8/23/2020 9:04:47 PM EDT by gman556]
Didn't make it out this weekend but just to keep the thread alive I am going to try next range trip without my handloads amd just new factory FGMM 168 gr match and some 155gr and 175 gr PPU.

Going to start over again with a heavier buffer weight and remounted the ADJ gas block. Going to try using just the reducer option instead of the bleed off this time around.

I got a 308 small base die from Redding and once I get at least 50 fired cases from the new factory ammo I'm going to size them with the SB die and do another range session with my handloads again and see what happens with them.



Link Posted: 8/24/2020 12:48:28 AM EDT
Your problem sounds like your reloads haven't been sized enough. You need at least .003" of clearance (shorter than fired case measurement's) for reliability. Sometimes more in semi-auto .308's because the cases can get stretched longer than actual headspace because of how violent the ejection process is.

You need gages. Hornady's Lock-N-Load works great and can be used for lots of calibers. My favorite is No DeFina's gages. RCBS makes an excellent micrometer gage similar to Mo's. Without a measurement in .001" increments you simply are guessing at how much clearance you have.
Link Posted: 8/24/2020 12:59:20 AM EDT
Slower powders increase port pressure. Faster powders decrease port pressures all other things being equal, namely being loaded to the same chamber pressure.

Mixing brass in .308 is asking for headaches. Different brands resize differently from each other based on their actual chemical composition.

No other caliber has such a wide variation in internal case capacity as .308/7.62x51mm. Winchester commercial .308 cases can weight as little as 155 grains. Military Surplus (foreign and domestic) 7.62x51mm can weight over 180 grains. What is safe in one brand is a serious overload in the heavy brass.

Link Posted: 8/24/2020 1:01:21 AM EDT
Use a magic marker or layout fluid to coat a case that sticks. Once it dries chamber it again. Once you remove the case you'll be able to see where the problem is.
Link Posted: 8/24/2020 8:47:56 AM EDT
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Originally Posted By borderpatrol:
Use a magic marker or layout fluid to coat a case that sticks. Once it dries chamber it again. Once you remove the case you'll be able to see where the problem is.
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I have the Hornady micro that goes on your caliper. I was bumping the cases down .003-005 with my die as I stated earlier. After a few still stuck I sized down to 008-009ish.

Also went with a heavier buffer but still had a one out of 50 stuck. I believe a member here stated to try a SB die next time around which I’m going to try. Also going with the ADJ gas block and the heavy buffer this time but going exclusively with factory ammo to rule out whether it’s my hand loads or not  I’m thinking it is my handloads in combination with the Rainier barrel chamber, hence trying the SB die next time I try my handloads.
Link Posted: 8/24/2020 10:04:30 AM EDT
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Originally Posted By limaxray:

ETA:  Using a case-length gauge won't show this problem, because all it'll really tell you is if the headspace is correct. My understanding is the gauges are cut to SAAMI max sizes, not  minimum, so it won't tell you if the brass will fit in YOUR chamber, just in the sloppiest one that's still in spec.
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I don't think that's correct.  The gauges are cut to the max cartridge size and the max cartridge still fits in a min spec chamber.  If the cartridge fits the gauge, it should also fit in any rifle that's in spec.
Link Posted: 9/5/2020 9:07:20 PM EDT
[Last Edit: 9/5/2020 9:07:59 PM EDT by gman556]
Finally got out to the range today and after adjusting the gas block fired 40 factory rounds of 155 and 168 gr PPU along with a another 40 rounds of Tula 150gr without a hiccup.

Looks to me like it definitely was my sized hand loads using the FL die.

Going to go with the small based die next time around and see what happens there.

I'm going to size these 40 1x fried PPU cases with the SB and maybe even pull down and resize some of the loaded casesI didn't get around to firing due to the issues I was having with stuck cases.

Anyways this is all I have for an update so far and I'll try and update again as soon as I can shoot the hand loads sized with the SB die.

At least now I can be pretty sure that it's something to do with the sizing of the brass. So I guess this thread does belong in the reloading section after all.
Link Posted: 9/7/2020 11:32:35 AM EDT
[Last Edit: 9/7/2020 11:34:47 AM EDT by limaxray]
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Originally Posted By TripletDad:


I don't think that's correct.  The gauges are cut to the max cartridge size and the max cartridge still fits in a min spec chamber.  If the cartridge fits the gauge, it should also fit in any rifle that's in spec.
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Yes, sorta.  My reloads with FL dies fit into a Forster case gauge, would fit into my DPMS tight chamber if I used the bolt release, but then wouldn't extract because it was too tight.  So, yes, all three of those separately were true--the cases were FL sized to within SAAMI spec, the case fit in a SAAMI spec case gauge, and the chamber was min spec to SAAMI standards...but it still didn't work.

I'm a dumdum when it comes to this stuff (I'm at a green light good/red light bad level of engineering--the phrase "aaaand the monkey pushes the button" was written for me   ), but I vaguely remember my mechanical engineering friend using the term "tolerance stacking" to explain what was going on.

All I REALLY know is small based dies solved my very similar problem.  
Link Posted: 9/7/2020 12:12:33 PM EDT
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Originally Posted By limaxray:

Yes, sorta.  My reloads with FL dies fit into a Forster case gauge, would fit into my DPMS tight chamber if I used the bolt release, but then wouldn't extract because it was too tight.  So, yes, all three of those separately were true--the cases were FL sized to within SAAMI spec, the case fit in a SAAMI spec case gauge, and the chamber was min spec to SAAMI standards...but it still didn't work.

I'm a dumdum when it comes to this stuff (I'm at a green light good/red light bad level of engineering--the phrase "aaaand the monkey pushes the button" was written for me   ), but I vaguely remember my mechanical engineering friend using the term "tolerance stacking" to explain what was going on.

All I REALLY know is small based dies solved my very similar problem.  
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I think in my case you are both correct.

My sized cases dropped right in my Dillon case gauge and were right in between the max and min steps but still got stuck in the chamber.

Today I measured the base just above the extractor grove on my FL die sized cases and they were .470 /Factory were .466

I'm crossing my fingers the SB die with do the trick with my handloads.
Link Posted: 9/9/2020 8:00:38 PM EDT
My DPMS 308 gave me fits with reloads that worked in all my bolt guns, very tight chamber and ultimately had to send the rifle

back to DPMS ,seems the chambers are cut way to tight !!

Finally had to resort to JB bore paste to smooth it out and greatly increased the amount of sizing cases...

I know your barrel is custom but you might want to keep on sizing your cases to see how the fit is..

Now she runs quite well but I stay away from once fired LC cases now using Winchester and Federal/Remington cases.

Hope this helps ..

Later - John
Link Posted: 9/9/2020 8:24:40 PM EDT
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Originally Posted By JohnInPA:
My DPMS 308 gave me fits with reloads that worked in all my bolt guns, very tight chamber and ultimately had to send the rifle

back to DPMS ,seems the chambers are cut way to tight !!

Finally had to resort to JB bore paste to smooth it out and greatly increased the amount of sizing cases...

I know your barrel is custom but you might want to keep on sizing your cases to see how the fit is..

Now she runs quite well but I stay away from once fired LC cases now using Winchester and Federal/Remington cases.

Hope this helps ..

Later - John
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Thanks

I believe my Rainier barrel chamber may be cut a little tight which is why I am trying a small base die once i get enough once fired cases.

I don't think I could find any LC cases right now anyway. I do prefer them in my gas guns.
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