Currently I am running a standard weight spring and an h buffer, every other mag the bolt fails to lock back on the last round tho,

i

What ammo and what gas port diameter?

im using russian mil surp from aim surplus,
gas port diameter....
http://www.shop.ar15hardware.com/16-Chrome-Molly-M4-545-x39-barrel-Bolt-combo-cit54539cmbarrelbol.htm

that is the barrel i am using

It'd be easier if you could measure the gas port diameter, all I know about Citadel 5.45 stuff is that they send out bolts that don't have the right extractor springs or properly heat treated extractors.





The gas port might be so small that it's not allowing enough carrier travel, or it might be so large that the BCG is outrunning the bolt catch spring's ability to push the bolt catch into place, or it might be an out of spec bolt catch, or a lower receiver issue. Do you have other lowers?

 

i do have other lowers,
currently I have it setup with a pof 3rd gen,
is your suggestion to first try using another lower to rule out the bolt catch assembly itself?
this citadel barrel was also waay way over .750 and had to get my gas block reamed out,
thing seems to run okay other than the 50% or so lack of lrbho

also about the heat treatment, are 5.45 extractors different than 5.56 ones, i have plenty of spare 5.56 extractors laying around

thanks for the input

eta the gun seems to recoil harder than its 5.56 brother as well, like i hear and feel the spring slamming around a lot more it seems

That would be the simplest (possible) solution at this point, switching lowers.





No buying additional parts, etc. See if it works, if not, decisions can be made from there.



5.45 extractors are different.

same deal on a spikes lower,
other than the fact that the cproduct mags barely fit in that damn magwell,

i noticed while cleaning that the buffer looks like it was seen much more abuse than the 200 rounds it has actually cycled

sorry about my lack of photography skills and 50 dollar camera

No, that depends on the bolt.

To my knowledge, Alexander Arms was the first to do a 5.45 upper (the Ghenghis).  I have some of their bolts and that is what I use for my builds.  I use Bulgarian chrome lined barrels that are headspaced for those bolts.  They use standard 5.56 extractors.  In order to do this properly, the bolt faces need to be machined deeper not just opened up.  If the bolts are NOT machined deeper then the headspacing is different and you cannot use regular 5.56 extractors reliably.

I've run many thousands of rounds in full auto with my AA bolt + my custom Bulgarian barrels.

Talk to Tom at Spike's Tactical.  I showed him the proper bolt depth to use standard 5.56 extractors a couple years ago and he got their bolts made to this depth.


Here is a link to a video of one of mine using BarrelXchange's 77 round 5.45 drum.
http://www.livevideo.com/video/F30DE5CDBC1D4920AC8B9CCF3EF413E2/5-45-upper-w-77-rnd-barrelxch.aspx

From what I have been reading about the Citadel 5.45 stuff, I would not expect them to go out of their way to machine the bolts to do that...





But anything's possible. I did mention 5.45 extractors to Tom a few days ago (in reference to a broken Citadel extractor), he didn't mention that theirs are 5.56...but he's a busy guy.





 

Well try a standard carbine buffer then...Is the gas block placed properly? I have never heard of a 5.45 AR that exhibited signs of short stroking with an H buffer and surplus ammunition.