Gunsmithing Troubleshooting AR 6.5 CR Bolt doesn't go fully into Battery

[perazzisc3]

New barrel installed and after fully cleaned 10 shots down range the bolt will not consistently fully go into battery.
After every round fired and a new round cycled into the chamber I have to use my thumb as a forward assist to
fully close the bolt.
AR gurus what are your thoughts???
P.S.
I am seeing some shiny spots on the bolt teeth like possible excessive wear.

 

[perazzisc3]

TTT

 

[6172crew!]

Is the bolt coming all the way back? Mag catch and a fired shot should answer that much. Resizing brass? Factory ammo? Does it do it on full magazine or ok with just 1 round left in mag?

 

[perazzisc3]

Is the bolt coming all the way back? Mag catch and a fired shot should answer that much. Resizing brass? Factory ammo? Does it do it on full magazine or ok with just 1 round left in mag?

the bolt will lock back if I only load 1 cartridge.
after fully cleaning the gun it shoots and cycles fine till the 9th or 10th shot then it starts not fully going into battery.
reloaded ammo , I checked every cartridge for proper head space and used small base die.
After each shot fired I check the bolt and use my thumb to push it into battery.
I see signs of heavy wear on 3 - 4 of the bolt lugs. I have not scrutinized the barrel extension yet.

 

[6172crew!]

Do you think it is possible your loads are leaving unburnt powder in the chamber area? Do you have a heavier buffer or spring to hold the bolt locked a few moments later? Sounds like the bolt is coming back and its still throwing fire and crap inside the chamber?

Wonder what it looks like at night? (does it have fire coming out of the ejection port?)

 

[perazzisc3]

Do you think it is possible your loads are leaving unburnt powder in the chamber area? Do you have a heavier buffer or spring to hold the bolt locked a few moments later? Sounds like the bolt is coming back and its still throwing fire and crap inside the chamber?

Wonder what it looks like at night? (does it have fire coming out of the ejection port?)

never fired it at night. it doesn't take much force to thumb the bolt in to battery
I am going to try a different bolt, I feel the barrel extension and bolt lock up may be part of the problem

 

[Mordamer]

Are you crimping your reloads?

 

[Mordamer]

Try a box of factory ammo. If all 20 shoot fine then it narrows it down to your reloads. If they don't shoot fine then worry about the gun.

 

[perazzisc3]

Are you crimping your reloads?

slightly

 

[perazzisc3]

After thoroughly cleaning the chamber and taking the first 10 shots is when I start experiencing the bolt not going to battery and have to push it in with my thumb.
This the second time it started occurring after 10 firings.
Could it be the chamber is too tight?

 

[chevytruck_83]

Sounds like your over thinking it. You have several really good suggestions. Try factory ammo. It will probably work fine. If not then go from there.

 

[jlang]

Post some pictures of your brass. I had some case head swipes in my 6.5 AR that would leave brass residue in the chamber which would prevent my rifle from going into battery and light primer strikes on occasion. Are you shooting 140gr bullets?

 

[perazzisc3]

Post some pictures of your brass. I had some case head swipes in my 6.5 AR that would leave brass residue in the chamber which would prevent my rifle from going into battery and light primer strikes on occasion. Are you shooting 140gr bullets?

Brass looks fine as can be from a semi. I have (2) 6.5CM & a 308 ( similar builds) (Mega Matens)
This issue started with the 22" Ballistic Advantage 6.5 CM barrel. The Criterion barrels has no issues.

My barrel loves 130gr's (Norma Golden target the most).I use a JPSCS, I changed the original spring to next heavier and seen a little improvement. My next range day will have the heaviest spring and hopefully this will do the trick. I am not too hopeful it will cure it completely. The chamber is very tight,(the good thing is it is very accurate) the bad after 10 - 15 rounds(fouled) this problem starts. I have to check the bolt with my thumb to sometimes assist the bolt to fully close.

 

[perazzisc3]

FINALLY!!!
If anyone is interested.
I figured out the reason why the bolt would not go fully into battery. The JP Silent Captured Buffer & Spring does not create enough force to close the bolt fully all the time
even after replacing the captured springs for the stiffer springs. The flat wire spring & standard 308 buffer does the trick.