I have a BM M4 upper that I have had for about 2 years now with zero problems. The last time I took it out, I had several failures to extract. The empty cases would stick in the chamber. I looked at the extractor/spring and it appears to my untrained eye to be in spec...nice sharp edge with typical wear. The casings do appear to have a few really small scratches which I am not sure is abnormal. I did take a military chamber brush and scrub it out good, but went out today with the same results. Very frustrating!

BTW I am shooting Olympic 55gr. which has never given me problems before in this gun. I assume that because the upper came from bushmaster that it is chambered for 5.56. Any ideas??

Thanks

Sticking in the chamber? Taking abnormal force to remove. Or just FTE.

There have been several threads here from people reporting problems with Olympic ammo. I've not used it myself, and now I'm not going to. My advice to you: try a different brand of ammo BEFORE anything else.

Usuall I have to run a rod down the barrel and tap it out.

I had not heard that about Olympic... I will try something else and see what happens. I also think will order another extractor/spring. It's cheap insurance even if it proves to be OK. Thanks for the help.

Ammo first.  Olympic has horrible QC issues that vary from batch to batch.  NEVER validate anything with imported, crappy ammo.

I don't want to unleash the dogs of hell here by asking this, but what IS a good,cheap ammo to buy?

Thanks for the advice...wish I would have known that before I bought 3 cases...

Quoted: I don't want to unleash the dogs of hell here by asking this, but what IS a good,cheap ammo to buy?

I don't believe that "good" and "cheap" go hand-in-hand when referring to ammo.

I buy Lake City XM193, and it's priced at $200/1000 rds.

Any good but inexpensive Winchester, Federal, Black Hills, etc...

PMP from south africa has been extremely consistent for me, and is fairly inexpensive. It's the stuff with the gazelle on it; .223, however.