I have a DPMS 20" with heavy barrel and for the longest I have had a problem of a shell getiing stuck in the chamber after fire. It happened off and on, every 10 rounds or so, any way I though it was the chamber since it was .223 not 5.56, so I polished out the chamber still had the problem. I checked my rounds that I reloaded for size they were fine so I remembered people here talking about a weak extractor spring but I didn't think much of it cause it wasn't happening on every round. When I reached my wits end I decided to go with altering the spring. Where I work I firgured I could replace the spring with a better one but no luck then while sitting there looking at my top drawer of my tool box I noticed my ink pen and thought the spring in it was about the same size so I took it out and cut it to length but I did not replace it with that one but coiled it around the old one leaving the rubber buffer there. Man What a difference! Went to the range today and not the first jam! not even one checked the extracted brass everything looks great all it needed was alittle re-engeering. All my headaches was fixed with a ball point pen. I plan on buying a new spring a buffer but for now she works like a champ.

Did you ever try an insert?

Are you full leanght sizing your cases??  Neck sizing may cause this problem on self loading rifles.  1 in 10 rounds is may to often for this problem. Also .223/5.56 basically is the same ammo and would not cause this problem.

Sgtar15

I haven't had call to use any of it, but I have a foot of high temperature model airplane fuel line coiled in my toolbox.  In the future, I can slice rings from it and make D-fenders by the dozen, if necessary.