LR-308 Cycling Issues

[WR4246]

In the middle of a LR-308 build and having problems getting the rifle to lock back on an empty mag and cycle a second round.  Using a Superlative Arms adjustable gas block with a Lantac eBCG.  Have tried the standard .308 buffer and spring, as well as, a Sprinco Orange spring with heavier 5.3 oz buffer but no luck with any of them.  Using a standard mil-spec 7 inch buffer tube.  Can get the rifle to lock back on empty mag when charged manually but not when fired.  Have changed the bolt catch to an Aero Precison .308 bolt catch but that has also not solved the problem.  After firing the first round the bolt group is hanging up just passed the end of the mag so you see the bolt in the extraction area.  Any suggestions or advice?

[DNP]

Start here.  Then measure the gas port in the barrel.  Gas block wide open while you’re doing this?  How many rounds through the rifle?  Soaking wet with oil at the moment? - if not it should be. 

 

[edgecrusher]

53 minutes ago, WR4246 said:

In the middle of a LR-308 build and having problems getting the rifle to lock back on an empty mag and cycle a second round.  Using a Superlative Arms adjustable gas block with a Lantac eBCG.  Have tried the standard .308 buffer and spring, as well as, a Sprinco Orange spring with heavier 5.3 oz buffer but no luck with any of them.  Using a standard mil-spec 7 inch buffer tube.  Can get the rifle to lock back on empty mag when charged manually but not when fired.  Have changed the bolt catch to an Aero Precison .308 bolt catch but that has also not solved the problem.  After firing the first round the bolt group is hanging up just passed the end of the mag so you see the bolt in the extraction area.  Any suggestions or advice?

Measure your recoil system with full details. There is no standard as you call it. None. DPMS parts are different than Armalite. Please lube liberally, liking dripping wet. Did you head space? Also, what receiver set are you using? Not mentioned.....

[tedgram]

4 hours ago, WR4246 said:

In the middle of a LR-308 build and having problems getting the rifle to lock back on an empty mag and cycle a second round.  Using a Superlative Arms adjustable gas block with a Lantac eBCG.  Have tried the standard .308 buffer and spring, as well as, a Sprinco Orange spring with heavier 5.3 oz buffer but no luck with any of them.  Using a standard mil-spec 7 inch buffer tube.  Can get the rifle to lock back on empty mag when charged manually but not when fired.  Have changed the bolt catch to an Aero Precison .308 bolt catch but that has also not solved the problem.  After firing the first round the bolt group is hanging up just passed the end of the mag so you see the bolt in the extraction area.  Any suggestions or advice?

I am having the same problem with Armalite. First 5 rounds trough a never fired rifle, round would look like it was pulled back and shoulder of the shell was stopped at entrance to the chamber. Took the rifle apart and lubed it until it was literally dripping. First round after that had an empty stovepipe. A few rounds after that neck of empty cases were caught on ejection port edge. After ten round cases were getting ejected but next round was not be picked up and empty magazine was holding bolt back. So far I've put 20 rounds of  IMI 175 grain Match through it and have it zeroed. Every part of this rifle seems extremely tight and maybe it just needs to wear in? Was thinking it is under gassed or buffer spring is to strong.

3 hours ago, edgecrusher said:

Measure your recoil system with full details. There is no standard as you call it. None. DPMS parts are different than Armalite. Please lube liberally, liking dripping wet. Did you head space? Also, what receiver set are you using? Not mentioned.....

 

[tedgram]

This is with a rifle length 20 inch. Empty magazine not holding bolt open. Will oil again and fire more rounds. Buffer spring shines and seems like it is quite strong.

[DNP]

Buffer system matters more than you’d think. Start a thread on yours with all sorts of details. Hell, share what you had for breakfast when you built it. Be that specific. 

[392heminut]

We need the internal measured length of your buffer tube (that will either be 7.00 inches or 7&5/8 inches) and the overall length of the buffer you're using just for starters. Those two measurements are huge! What are they?