Bolt not locking back

[Mdt]

Need some help to figure this problem. I built this Gun my self with quality parts and did not take any short cuts.
WHAT I HAVE: Aero Precision Billet upper and lower parts kit. Aero Precision bolt carrier group ,carbine length buffer tube, H2 buffer & heavy red spring(got from LaRue), Superlative Adjustability gas block, Proof Research barrel 6.5 Creedmoor.
WHAT THE PROBLEM IS: The bolt will not lock back on the last round even with gas block wide open. I noticed that the bolt when manually charged is only locking back on the mag follower(empty mag) and not the bolt catch. Therefore , when you press the mag release the bolt goes to the battery.Now, I can manually lock the BCG back on the bolt catch, but this isn’t proper function.

Thank you for your help
Mike

 

[FisherT&C]

Your buffer spring may be too long or too heavy. Also, your buffer could be bottomming out on the buffer tube, which means your buffer is either too long or your buffer tube is short. I would eliminate the spring as the culprit first, the other possible causes are the least likely.

 

[Thereaper1313]

First thing I'd look at is the gas block. Make sure it didn't rotate slightly during installation and is causing the gas port to be partially blocked.

 

[Halfnutz]

Reduce spring or try an H1 buffer.

 

[Thereaper1313]

Buffer weight and spring should only affect cycle speed. A 6.5 will have plenty power to push any buffer if that gas block is truly wide open.

 

[Snuby642]

That about covers everything except what I had a few days ago.

My 6.5 was intermittently failing to lock back. It was filthy from running suppressed the last time and needed cleaned and lubed since the normal adjustment is barely enough to lock back.

I would start at gas block alignment especially if your barrel was not dimpled like @Thereaper1313 said.

Then for a quick check toss a standard spring in there like @FisherT&C said.

H2, I use them on several calibers and barrel lengths, would be my last suspect but also easy to test.

If you take the super spring and a standard spring compressed side by side it may show something..

Catching on the magazine itself?
I can't remember that ever happening. Can you get a different one to test?

 

[Missalot]

First, try different magazines.

 

[Snuby642]

Make a spreadsheet and get back to us.

Lol