6.5 Short Stroke? Update: Problem Solved

[montana]

Thanks everyone for the tips and suggestions. Here's what I have determined so far.
Changing to a carbine lower with standard weight buffer improved functioning to almost 100%. Only one mag out of the 5 that I tried failed to chamber a round and lock back on the last round. I put it aside for now. My remaining mags ran perfectly.
So, it appears the rifle buffer and spring were too heavy for this rifle. That does not mean it is the only possibility.
The problem may still be in the gas system since I have built rifle length uppers before and they ran fine on this A-2 stocked lower.
Further testing will continue after I get my hands on a bore scope and take a look at the gas port and block alignment.

Also, can anyone tell me where I can find out the proper gas port size for rifle length gas for 6.5 Grendel? If my port is under-sized, as some have suggested, that my be the answer.
Thanks, R.

I had to open up the gas port on a 20" 5.56 rifle length Faxon barrel. I called Faxon and they gave me permission to proceed before I sent it back..They were great to work with. I have the correct chucking reamers-drill bits and pin gauges to do it properly.. If you try this, place a steel cleaning rod in the bore before you drill so you won't hit the side of the bore opposite the gas port.. I gradually opened the gas port, while test firing after each increase to get the proper port size..If all things were equal, a standard size gas port would work..Most rifles and ammunition are not equal..Drilling the gas port is the last option I will use..If you over size the gas port, you will have to adjust the gas some where a long the process, adj gas block, adj bolt carrier, adj gas tube, install a new gas tube with a smaller port, etc..