Re: ar-10 feeding problems... need help
Jacq,
If the round in the mag is not presenting itself sufficient to make contact with the bottom of the bolt adequate to strip off the loaded round from the mag and into the chamber of the rifle the problem may be the mag lips being curled in and down too much. This is possible, but I would hope DPMS has not sent out a product failing to be serviceable for its intended purpose. That makes them lemons, if so. However, this could be one of your problems. The lips might require bending to adjust the round presentation for proper feeding cycle. One may also sand / polish the inside parts of the lips that contact the casing. First, 400 grit, then 600.
Also, on new guns, I have found the carriers' finish to be far too rough for reliable service in my view. I sand the rough finish off with 400 grit sand paper. This allows for slicker sliding of the carrier in the receiver and easier cleaning of the carrier too. Resistance caused by this rough carrier finish can contribute to the problem you're experiencing.
Third, mag springs can be too stiff. Load the mag and leave a few days while some new mag springs from Superior Shooting Systems get shipped, along with:
Buffer Spring. They're crappy too. Get a better one from Tubb. They are better in every way. Since you're ordering springs, replace the hammer and trigger springs too. Remove the recoil spring and clean the recoil spring housing tube while your improved Tubb spring is in transit.
Last, polish the bolt face. Chuck it in a hand operated drill or screw driver. Hold 400 grip sandpaper on the bolt face after having applied some machine oil. Allow some of the sandpaper to enter the bolt face so as to polish the extractor making it easier to jump over the case rim. Using a 223 casing or something similarly sized and shaped, allow some sandpaper with oil to enter completely into the bolt face area on which the case head impacts. Just a few revolutions will do. Finish this polishing procedure by repeating with a cloth, terry or tee shirt, and polishing compound applied such as Flitz or the like. Clean all this mess off with brake cleaner under aerosol pressure.
Grease the lugs, bolt, and carrier. Not oil. Oil will end up on your rounds below the bolt carrier group then in the chamber and thats bad. Use grease. Remove it after shooting with brake cleaner, oil the parts between firings, and remove the oil the same way before shooting and re-apply the grease before firing.
Nothing is wrong with these guns; except sometimes they simply are not ready to be fired (reliably).
Consider an AR doctor to perform this fine tuning.
These are not my ideas, but i've tried them and they work. I got these ideas from:
The Competitive AR15, by Glenn Zediker.
