while shooting yesterday I began to experience failure to feed problems. I was sighting in a new upper on my BM lower. A few months ago I had installed an Olympic Arms Pneumatic Recoil Buffer (can't remember the model No.). After 6 shots or so the scope is zeroed so I begin working on groups at 100 and 200 yards. Somewhere around 60 or 70 rounds I begin to experience failure to feed. The rifle had been cleaned prior to the trip. So my conclusion is the pneumatic buffer is probably the problem. Has anyone else experienced this? Am I wrong, have I misssed something?  

I'll be taking out the buffer today and inspecting it for any adjustments, but I'll probably reinstall the original spring assembly in the buttstock.

BTW I was shooting a BM 20 round mag (generally half full). After the feed problems began I switched the mag over to another AR and it worked just fine. So it wasn't the mags fault.

Can you give more details about what exactly is happening during the FTF... A better description to what exactly is happening is needed...

Sorry for the incomplete info...The problem was that upon the return the bolt would not strip off the next round from the magazine. There just wasn't enough umph to chamber the round. Hope this helps.

Is the bolt grabbing then pushing on the rim of the casing but then fails to completely strip the round out of the mag and freezes before it can feed it into the chamber?

Or is it that the bolt face is not grabbing the casing and is slamming shut with out feeding a round into the chamber?

The bolt is grabbing the case but doesn't have the power to drive it into the chamber.

You could have a bent gas key or gas tube... Remove the bolt from the carrier and drop the carrier back into the receiver and then slide it back and forth to see if it binds... If it binds check the key and gas tube to see if one of them are bent... ETA: If the gas tube is the problem, contact the vendor for repair or replacement...

If the carrier and gas tube check out OK, the buffer could be causing the FTF problem... Install the original buffer and spring to see if it corrects the problem... ETA: If this is the problem, contact the vendor for replacement...

Thanks...I'll go inspect sometime tomorrow.

Just thought of something... Is the pneumatic buffer adjustable?
If so, maybe it needs adjusted...

No, just checked. I am taking the buffer out tomorrow and shoot with the spring next week.