Failure to Extract problems

[gatordev]

I'll have to see if the length is the same, but it is NOT a standard carbine buffer. It's 8.5 oz coupled with his longer-than-standard .308 spring. Regardless, it made it all work, so call it what you want.

[Deadwing]

I haven't got the gun assembled yet, but i've got a MATEN set and a RA UltraMatch 20" barrel waiting for me to get off my lazy ass and build it. I bought a stock/buffer/receiver extension kit from LMT. The receiver extension is the same length as the Vltor A5, and the buffer is an H3 (same physical dimensions and weight as another AR15 H3 buffer i had sitting around). The action springs i purchased to use with this set-up are Armalite AR10 rifle length springs. I've got my fingers crossed that this combination of parts will function well.

Originally, i had purchased the DPMS buffer that was designed to run with standard AR15 carbine receiver extensions, but had my doubts about the ability of that set-up to effectively regulate the cycle of operation.

Glad to hear the heavy buffer did the trick. I'll definitely keep this in mind for when i finally get my MATEN assembled and test fired.

[gatordev]

I shot the rifle again the other day doing a quick op check with crap ZQI 147gr (which was meh). It still is over-gassed, especially with the can. Like crazy over-gassed. But it functioned 100% suppressed or unsuppressed.

Given Rainier's pedigree, I'm a little surprised how gassy the system is. I understand a manufacturer has to find that sweet spot between people shooting crap ammo and those shooting spec ammo, but given how much weight and spring length is behind the BCG now, it seems this barrel is a little excessive.

It would be interesting to shoot this upper on my KAC lower, which is pretty close to an A5 setup. Maybe something to try another day.

[SwissyJim]

well, got out and finally shot my .308 with the new adj gas block I put on (and pinned! first one) and I found the same thing - my Rainier barrel is pretty gassy! I have the block slightly less than half closed and I have perfect 4 o'clock ejection, about 5 feet from the rest. Put the can on, and it changes to about the 2 o'clock position but also about 5 feet out. Total lockback on last round and no issues stripping the next. Brass all looks spotless - on marks at all, unlike before the block change. And that's with the heavy buffers spring and buffer.

Altho I found I had sold off my original 308 spring and buffer, which was why I went with the adj block! Now I need to order another setup so I can test the subsonic possibility. I'm still hoping beyond hope that with the barrel as gassy as it is, with the lighter spring/buffer setup (using the Heavy Buffers setup now) and the gas block open all the way, that I'll be able to have a functioning 308AR that shoots subs! Then I can dial back the gas and shoot supers when needed. How cool would that be?!? It's worth a shot to me, and even if it does not work I'm ok with the adj block setup.

Glad you got yours running Gator... the 308 is fun. Mine is going with me next year to the boating long distance shooting trip, and I'm pretty sure we can get a target out past 550yrds

[OTShooter]

What kind of gas block does this gun have? I'm thinking that the extra back pressure is causing the over-gas situation. My SIG 716 has a 4 position gas block: normal, "adverse" (open more than normal), suppressed (partially off) and off. Yes, this is a piston gun, but the concept is the same. Like a Noveske Switchblock, which has off, suppressed, and unsuppressed settings. I don't know if the Noveske would work with your barrel, but that's the direction I'd go.

There's a balance you'll need to establish between gas quantity and buffer weight with any AR-type gun, but since the issue is only when suppressed, it looks like the first step would be to get control of the gas issue, then figure out the buffer later.

[BoilerUp]

... I'll be able to have a functioning 308AR that shoots subs! Then I can dial back the gas and shoot supers when needed. How cool would that be?!?

Why do you want to handicap a .308 down to subsonic? Because you want the ballistics of a 300 BLK out of a 10 pound weapon?

[SwissyJim]

Why do you want to handicap a .308 down to subsonic? Because you want the ballistics of a 300 BLK out of a 10 pound weapon?

because it's a challenge to get a sub round to cycle a 308AR, it'd be fun at the range and for no other reason than to see if I can.

[SwissyJim]

What kind of gas block does this gun have? I'm thinking that the extra back pressure is causing the over-gas situation. My SIG 716 has a 4 position gas block: normal, "adverse" (open more than normal), suppressed (partially off) and off. Yes, this is a piston gun, but the concept is the same. Like a Noveske Switchblock, which has off, suppressed, and unsuppressed settings. I don't know if the Noveske would work with your barrel, but that's the direction I'd go.

There's a balance you'll need to establish between gas quantity and buffer weight with any AR-type gun, but since the issue is only when suppressed, it looks like the first step would be to get control of the gas issue, then figure out the buffer later.

Sorry... maybe need to clarify. Gun runs fine, I'm just goofing with it to see if I can use the overgassiness (word?) to my advantage and combine it with the lightweight OEM spring/buffercomboto try and get subsonic loads to actually cycle the gun.

[gatordev]

So I may have finally tamed my rifle without having to file for domestic abuse charges. As usual, the problem was solved by eventually throwing the right amount of money at the problem. I need to do some more shooting to confirm, but after a few rounds of crappy ZQI and some 7.62 FGMM, I appear to have a fully functioning suppressed rifle. The solution: A Gemtech Bolt Carrier. The rifle now feels much closer to my SR-25. Also, before the Gemtech, I encountered the original issue come back with FGMM 7.62 (but not .308, interestingly) and a Brownell's mag. PMag worked fine, but not so much with the Brownell's. Today, both mags worked equally well with 7.62 FGMM.

What's crazy is it would still cycle the ZQI unsuppressed while on the suppressed setting, although it short stroked about 40% of the time. I'm so much happier now and will probably try and do a little more accuracy testing with some 175 SMKs soon. At the very least, I know this is a 400m rifle, and now it will be a little more pleasant to try farther.

[Former11B]

Why do you want to handicap a .308 down to subsonic? Because you want the ballistics of a 300 BLK out of a 10 pound weapon?

I run subsonics from my .308 occasionally. 150gr flat point over Trailboss. It's fun with the can on, super quiet, and I don't have or want/need a 300BLK. Win/win IMO

[Joelski]

I'm surprised nobody's developed a damper system to address this issue. Think in terms of a monoshock motorcycle suspension; a compound, rising rate spring to dampen recoil, and a shock absorber to control rebound. A tuneable system like that would cure any problem that currently affects overgassed, underpowered systems.

[gatordev]

I'm surprised nobody's developed a damper system to address this issue. Think in terms of a monoshock motorcycle suspension; a compound, rising rate spring to dampen recoil, and a shock absorber to control rebound. A tuneable system like that would cure any problem that currently affects overgassed, underpowered systems.

What you're describing wouldn't solve the actual mechanical issues that result in an over-gassed (or even an under-gassed system). It would feel great to the shooter, but doesn't solve the actual auto-loading issue.

[Sak007]

Apologies for upcoming rant but it's been trapped in my head and needs release
Random AR10 issue .A couple of months ago I went to the range to sight in and was having issues - still not sure if barrel or scope related but I could not get on target for the life of me and was become more than irritated as I have dumped waaaaaay to much into building this multi year project that still is having issues .
I had a 20rd mag left so I just wanted to fire it off to let off some steam & at some point through this it slam fired and scared the shit out of me and my spotter. I wasn't hurt but the bolt was locked up pretty bad with no obvious damage .
When I got home I had to beat the crap out of it to get the bcg to go back and gouged a chunk out of the inside of the upper . Much to my surprise the bcg seemed intact along with barrel etc. . Tried to take barrel off and barrel nut wouldn't budge so I let it sit in the safe as I had other projects that get more use to work on.
The last couple weeks I've been thinking a lot about possibly building a 6.5cm upper or getting a RPR so I decided to bust my upper out of the safe and take it apart . Long story long i had to soak it in pb blaster to even get it to budge at which point it locks up & i'm thinking shit there went the threads , more soaking finally get it off with the last couple threads on the receiver getting a bit stripped .
All looks good until until I notice the barrel pin is seriously bent .
I think the chamber swelled and caused the issue with the barrel nut locking up and was curious for some input on the whole series of things that lead to where we are now , and wondering where to go from there ?
Do I play it safe and assume bcg & upper are a loss because them may be damaged and be out of spec ?
Barrel isn't worth fixing so I will replace that .
How do I even check any of these parts without spending money I could put into new parts just to be safe ?
If it turns out upper is ok what barrel do I replace it with & what length ?
This rifle was way over gassed so I don't wanna run into the same issues when I go at this again so here is a parts list of what was in it & what I want to replace .

Current build out
Mega Maten set
24in Black Hole barrel
Sadlak low pro gas block
standard rifle length gas tube
Sandman Ti
DPMS chrome bcg
Jp silent capture spring heavy spring

If the receiver is ok I will sell set to a buddy to fund a 2_a Xanthos set
16 or 18 barrel will be running suppressed and generally shooting up to 500yds -I plan on getting a Ruger rpr in 6.5cm down the road for longer distances
Superlative Arms "bleed off" gas block - hoping this will help with the over gassing or is it necessary ?
Bcg ? If bolt is done replace with a Jp high pressure bolt or if whole thing is toast what bcg ?

Again I apologize for this monstrosity that is this post but I need some re assurance as I don't feel good about a gun I don't trust

[Sak007]

bump

[SINNER]

So basically you had an out of battery discharge that damaged a steel barrel extension and caused visible physical damage to the upper when you removed it and you want to know if it's OK to sell it?

Seems like that question should answer itself to me.