Problems with new AR10 build cycling.. OPINIONS NEEDED!

[Jv22]

Hi and thanks for any input you may have to help me diagnose this issue. I am by no means a professional gun builder. Only a professional ammo user.

The rifle: Ar10 DPMS style, 308, 20" BCA side charging upper receiver complete from them.

The issue: Here is the order of operations.
-Insert mag
-Charge first round
-Boom
-Ejection
-Self loads next round successfully and bolt is completely foreward (I checked that it was in it's most foreward position multiple times)

-CLICK

-Manually charge next round (and observe un-spent round that came out)
-Notice immediate light primer strike And marking on case heads.

It's like the case head isnt seating properly or getting stuck some how and the primer isnt able to be struck properly. Please observe the pics- the only way I could get it to fire after *click* is to manually charge the next round. Also worth noting that it was very hard to pull the side charger back after a *click*.. so I believe something is definatly stuck.
Any ideas ? Like I said, brand new Bear Creek Aresenal upper out of the box... here is a link.

.308, 20" Stainless SOCOM Barrel, 1:10 Twist, Rifle Length Gas System, 15" MLOK Split Rail|New MLOK Side Charging Upper(Gen 2)

This Bear Creek Arsenal AR-10 20” .308 complete upper features the new handguard and is guaranteed to give you phenomenal performance and accuracy at a great price!

www.bearcreekarsenal.com

If you guys think it's something wrong with BCA putting it together or something I can get ahold of them.. thanks again for ANY input good bad or ugly. This is America after all and you can damn well say whatever you want. Cheers!

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[Member 34319]

I'll go out on a limb and say that it is barely cycling that steel cased ammo. Might have enough to eject, but not enough to strip a round AND fully chamber it.

Do yourself a favor and go to a store and buy quality 308. Redo the trial with that. Come back and let us know if that fixes the problem.

AR to dos: Use quality brass ammunition on first outing.

AR donts: Use steel case ammo on first outing.

 

[Ops]

check the hammer spring. hammer follow. always going to see a primer strike. its a free floating firing pin

nothing wrong with steel case.

also 1 round, does the mag lock back?

 

[arakboss]

Have you tried brass cased ammo yet?

 

[Arne K]

Could be under-gassed. After trying the suggestions above, check for gas block alignment and also the gas port size in the barrel. I had struggles with a factory rifle that ended up having an undersized port.

 

[Char77]

Sounds like it's not going completely into battery (presumably caused by the carrier not cycling as far back as it should) which would stop the firing pin from protruding all the way. Are you checking that it's in battery visually? By pushing on the charging handle? The ejector springs on the Aero M5 and Stag-10 bolts that I have are so stiff compared to an AR-15 that a normal forward assist is basically useless; they may be stiff enough that the carrier will feel like it's all the way forward even when it isn't. Some (but maybe not all?) of the marks also look like they are from the ejector.

As long as the *click* is the hammer falling it makes sense that it would take more force to pull the handle back since you're also re-cocking the hammer in addition to working against the recoil spring that you normally feel.

 

[Jv22]

Thank you guys. Okay one at a time-

-I honestly did not expect to have any problems and didn't bring any of my high quality rounds amature mistake. But in all fairness I run tula and wolf in all my other ar platforms with very little issues (if any). Only a handful over years and years span. Wonderful suggestion @Reno I will try that within the coming days and report back.

@Ops What exactly would I be looking for? Obvious broken springs? Please elaborate. I did build the lower so I will check if I installed the spring wrong but confuses me as to WHY would it cycle and fire ANY time I cycle it by hand? Yes locks open properly on last round.

@arakboss I need to take it back out and replicate the test with the brass case. Also going to spray a very light lubricant in some spots to see if that helps. Will report back.

@Arne K So theoretically, if I take the rifle back out and it still doesnt cycle the bolt all the way (or leaves light primer strikes) would you look at the gas immediately? Or like ops said maybe look for a stronger hammer spring.. not sure yet. Dont think it's the buffer tube or spring tention in there but this is why I need help.. guidance to narrow this down so Thank you guys all so much.

Heres the plan
-inspect hammer spring assembly for incorrect operation/installation
-replicate test with brass case.
-report back

Anything else? Really appreciate all the good info.

 

[Arne K]

I forgot one of the most basic things. Oil the hell out of the BCG, like make sure the bolt is drenched with CLP or similar inside the carrier. Sometimes .308's require a little more patience during break-in.
If it it doesn't lock the bolt back on an empty mag, that frequently indicates an under-gas situation. Check all of the above as well.

 

[Jv22]

Sounds like it's not going completely into battery (presumably caused by the carrier not cycling as far back as it should) which would stop the firing pin from protruding all the way. Are you checking that it's in battery visually? By pushing on the charging handle? The ejector springs on the Aero M5 and Stag-10 bolts that I have are so stiff compared to an AR-15 that a normal forward assist is basically useless; they may be stiff enough that the carrier will feel like it's all the way forward even when it isn't. Some (but maybe not all?) of the marks also look like they are from the ejector.

As long as the *click* is the hammer falling it makes sense that it would take more force to pull the handle back since you're also re-cocking the hammer in addition to working against the recoil spring that you normally feel.

THIS sounds closer to what is going on-- there is a strong little round ejector mark on each round clearly visible. Since it is a side charging upper it was very difficult to cycle back like you said so I do think it's not completely cycling back all the way when in battery. It SEEMED like the charging handle was all the way foreward- I even pushed on it foreward but without the forward assist I cant be completely sure it was 100% locked foreward. I will look for this specifically when using higher quality brass cased ammo. I expect the problem to still be there as I have always had very good luck with steel case HOWEVER it Is a brand new rifle, I know it's still nice and tight and not "broken in" (even though I think that's a bullbubblegum excuse IMO) Thank you @Char77

 

[Member 34319]

Thank you guys. Okay one at a time-

-I honestly did not expect to have any problems and didn't bring any of my high quality rounds amature mistake. But in all fairness I run tula and wolf in all my other ar platforms with very little issues (if any). Only a handful over years and years span. Wonderful suggestion @Reno I will try that within the coming days and report back.

@Ops What exactly would I be looking for? Obvious broken springs? Please elaborate. I did build the lower so I will check if I installed the spring wrong but confuses me as to WHY would it cycle and fire ANY time I cycle it by hand? Yes locks open properly on last round.

@arakboss I need to take it back out and replicate the test with the brass case. Also going to spray a very light lubricant in some spots to see if that helps. Will report back.

@Arne K So theoretically, if I take the rifle back out and it still doesnt cycle the bolt all the way (or leaves light primer strikes) would you look at the gas immediately? Or like ops said maybe look for a stronger hammer spring.. not sure yet. Dont think it's the buffer tube or spring tention in there but this is why I need help.. guidance to narrow this down so Thank you guys all so much.

Heres the plan
-inspect hammer spring assembly for incorrect operation/installation
-replicate test with brass case.
-report back

Anything else? Really appreciate all the good info.

Another thing to try, as I'm still thinking it is short stroking due to underpowered steel ammo, is to give the charging handle a good whack forward. Since it's a side charger, no forward assist I'm guessing, the charging handle is the forward assist. If it isn't cycling far enough to get the full forward force of the recoil spring to chamber a round, give it a good whack into battery. Should help get that steel stuff to at least run until you get some quality ammo.

 

[Ops]

308 buffer?

 

[Jv22]

Another thing to try, as I'm still thinking it is short stroking due to underpowered steel ammo, is to give the charging handle a good whack forward. Since it's a side charger, no forward assist I'm guessing, the charging handle is the forward assist. If it isn't cycling far enough to get the full forward force of the recoil spring to chamber a round, give it a good whack into battery. Should help get that steel stuff to at least run until you get some quality ammo.

I have some on hand I'm going to try here very soon. I'm also going to soak the BCG in oil as recommended. I may have the hammer spring wrong but that doesnt make sence why the first round always fires and then I have to manually charge it to make it fire again?

 

[TTSX]

Did you forget your disconnector spring? Sounds similar to a problem I had once

 

[Ops]

springs to weak on followup. hard to explain physics

 

[Jv22]

Did you forget your disconnector spring? Sounds similar to a problem I had once

This is a good point.. when assembling the lower I thought I had it mixed up with another, so had switched them how I thought they should be.. when I get it broken down i will post pictures of what spring is where and how the hammer spring is like @Ops Said. Thanks guys

 

[eldbillbo]

Granted my first guess would be a backwards hammer spring. I have had people come to me with the same problem and that is what it turned out to be, However looking at your ammo photos
it looks to me that the primers are set a little deep. Granted that does not explain why the first round fires and the second one does just an observation of the photos. Does anyone concur?

 

[Jv22]

Granted my first guess would be a backwards hammer spring. I have had people come to me with the same problem and that is what it turned out to be, However looking at your ammo photos
it looks to me that the primers are set a little deep. Granted that does not explain why the first round fires and the second one does just an observation of the photos. Does anyone concur?

I really hope it's that simple I would rather feel dumb than have a problem that's more complicated.

 

[DirectDrive]

My Internet Guess is that it's the hammer spring in backwards.
And then it's exacerbated by the hard cup Putin primers.

 

[nwslopoke]

Are you using a milspec trigger or a super lightweight upgrade? I had similar problems one my 7.62x39 AR. At the time I had no brass ammo. 3.5lb trigger on steel cased wouldn't work.

 

[Jv22]

Are you using a milspec trigger or a super lightweight upgrade? I had similar problems one my 7.62x39 AR. At the time I had no brass ammo. 3.5lb trigger on steel cased wouldn't work.

It's a "milspec" ar10 LPK and ar10 buffer tube kit. What was said above about the hard primers and primer depth is very valid but seems to be more prominent in the 7.62x39 builds. I'm anxious to break down the lower, check out the springs such, and get back out with some higher quality ammo. If it's fixed, I will personally buy each one of you a

Edit: @nwslopoke what ever ended up fixing your problem?