AR10 Accuracy Issues .308

[RC556]

Finally finished up the build today and range day was a shit show trying to get it on.
Shots were SO inconsistent. 4-5MOA @100yds w/ 168 Hornady Match.
I would also manage double tapping & sometimes triple tapping randomly.

Build is as follows:
M5E1 Upper & Lower
18" Hybrid Criterion Barrel
KAK Industries BCG
JP Buffer & Adj. Gas Block
Geissele 2 Stage
I recently put a Razor on top in an ADM mount, mounted on by very reputable Interstate Guns.

Anyone have any guesses where I'm going wrong?
I will say it is overgas'd as it throws brass about 6 feet at 1 o'clock.

 

[Snuby642]

Did you adjust the gas block?

And try smk 168 insread.

 

[RC556]

Did you adjust the gas block?

And try smk 168 insread.

I got it to a more reasonable ejection. I am new to the big bore platform so I wasn't sure what I was getting into

 

[Snuby642]

Its not that I hate hornady but the federal gmm 168 is a proven standard.

That solves one variable to a known standard.

The gas block test one round at a time till it just locks back the bcg no extra unless for service.

Is that an ajustable buffer ?

 

[RC556]

Its not that I hate hornady but the federal gmm 168 is a proven standard.

That solves one variable to a known standard.

The gas block test one round at a time till it just locks back the bcg no extra unless for service.

Is that an ajustable buffer ?

Sometimes the charging handle refuses to come back, if it does come back it is like a 30lb weight. Doesn't lock back with bolt release either

 

[Snuby642]

I'm just guessing you have a jp adjustable silent capture setup?

I am no help on that but do know it can cause frustration.

Go to jp site and look in help section or call support.

Plenty of people use them.

You could adjust that to a midway point and see if it will let you manually lock back without burning ammo.

 

[Snuby642]

Found this.

 

[Snuby642]

Well that video lets me know it does not adjust as I thought but gives you a couple of things to check for operation.

 

[FCS]

How heavy is the JP SCS? Get the spring kit too with various K for the SCS?
HS NM adjustable 2 stage or fixed, drop in 2 stage?

What stock are you using?
Won’t lock back when you pull charging handle all the way to the rear?

Second using some 168 FGMM. Hornady has some known issues in gas guns.

 

[aaronk]

In regards to the double and triple taps... I have shot thousands of rounds through the AR15 platform and have never had a double tap, first time out to the range with my AR10 with a 2 stage 2lb CMC trigger and I double tapped twice, scared the crap out of me. Very easy to bump fire a second shot in the AR10 platform with a light trigger, especially if you shoot from reset as you can reset that trigger before the recoil impulse has finished pretty easily on an AR10.

Need more details on the buffer weight and buffer length to help on the other issues.

 

[Snuby642]

I had a bad habit of instantly jumping off the trigger, shotguns, idpa or likely just bad habbit unconsciously repeated.

Strangely shooting a rack with 22 lr and forcing myself to wait for the steal plate to finish rotating before resetting trigger helped. (Forever amount of time in my head)

Consciously holding the trigger back did help with group size in my rifles.

Recently put a new 6.5g upper on my favorite 5.56 lower that small difference caused a couple of doubles till I got back to basics. New toy excitement.

 

[bfoosh006]

Sometimes the charging handle refuses to come back, if it does come back it is like a 30lb weight. Doesn't lock back with bolt release either

Manually ? or doesn't lock back when fired ?

Approx. where is the brass ejecting to now ?

Did you clean the chamber thoroughly prior to firing ?

What buffer weight and whose recoil spring ?

 

[RC556]

Manually ? or doesn't lock back when fired ?

Approx. where is the brass ejecting to now ?

Did you clean the chamber thoroughly prior to firing ?

What buffer weight and whose recoil spring ?

Manually doesn't lock.
Brass gets thrown about 8 feet at 1:00.
Spring, weight, tube is the only thing i kept from stock from Aero.

 

[Precision Underground]

Manually doesn't lock.
Brass gets thrown about 8 feet at 1:00.
Spring, weight, tube is the only thing i kept from stock from Aero.

If it wont lock back manually it sounds like your buffer tube is too short for what's inside.... Assuming the catch is installed correctly and free to move. When you pull the handle does the buffer bottom out before the bolt gets behind the catch?

 

[RC556]

If it wont lock back manually it sounds like your buffer tube is too short for what's inside.... Assuming the catch is installed correctly and free to move. When you pull the handle does the buffer bottom out before the bolt gets behind the catch?

She'll rack all the way back but it wont hold. And it takes almost 2 people to pull back when theres no mag with 1 in the chamber.

 

[FCS]

Sounds like short Head Space (HS) and bolt is jamming shoulder of case into shoulder of chamber. Possibly short freebore, bullet jamming into lands.
No reason it should be that hard to extract a live round from chamber.
Was bolt headspaced to bbl when chambered? If no, has HS been checked with go / no go gauge?
“Problem” w/-10 is there isn’t a mil spec on bolt face recesss. I’ve seen 5-6 thousands difference between mfg’ers of -10 bolts.

Sounds like BCG is not coming as far back as it should.
Pictures of bolt fully retracted by CH relative to bolt stop would be helpful.