Well I'm fairly new with the AR's so don't have a clue as to what my problem is.
Actually I have two bushmaster's....a shorty and a 20" v match.

I had a local gunsmith to do a trigger job on the shorty and now it seems that the firing pin just barely dents the primer which most of the time two out of ten shots will not fire. What did he do wrong?
My other gun a xm15 e2s sometimes will stovepipe with the round coming out of the mag.
In otherwords the spent case is not ejected out the port before the fresh round from the mag.
Is this a mag problem you think? I did use two diferent Bushy 10 round mags and had no problem
but with a 20 round Adventure mag it would jam. I bought this gun new about a month ago and it jammed after every shot. Took it back to the dealer and he swapped out the bolt from a new Bushy that he had.  
Any idea's? Can I rule out the extractor and ejector even though its only been shot less than 100 rounds?

Stupid questions I guess.....

Take it to the troubleshooting forum.
cpermd

The light primer strikes sounds like he might have lightened the hammer when he did the trigger job, and got it too light, or possibly he weakened the hammer spring to lighten the pull somehow.

The stovepiping sounds like it could be the ejector.  It doesn't matter that it has only fired 100 rounds, other than the fact that it isn't even broken in yet.  Are you cleaning and lubing according to the military spec manual, and only using CLP?  Have you lubed the ejector according to the manual?  If all else fails, and your lube procedures are up to spec, then some people find they have to replace the ejector spring.  

You say it does this with only the adv. line 20 rnd. mag, but not the 10 rounders?  You might try using a few different mags.  The 20 rounders are typically the most reliable, however.  

I've had that same stovepipe problem with a couple of Bushmaster shortys.  It most likely isn't an ejector problem but an extractor problem.  Basically your extractor isn't holding on to the casing well enough to facilitate ejection.

After speaking with Bushmaster, they suggested that I NOT use CLP and try a teflon based lube like rem oil.  After switching, the problem has disappeared.  You also might want to try adding one of the "D" rings under the extractor spring to increase the clamping force.

HTH


Saleen

Quoted: I had a local gunsmith to do a trigger job on the shorty and now it seems that the firing pin just barely dents the primer which most of the time two out of ten shots will not fire. What did he do wrong?

Those darned local gunsmiths! They'll screw you up every time!

I'll take a stab here.  Only two areas that could be screwed up here:  1) The hammer ain't hittin the firing pin hard enough, possibly due to an incorrectly installed or binding hammer spring, or a too weak aftermarket spring.  Unload the rifle, unload it again, then check that its really unloaded, open upper, and check that the hammer moves freely when you pull the trigger - just don't let it slam on the front of the lower.  Recock the hammer with your thumb and check it again. Seem OK? If not, take it back to el loco, er, local gunsmith if you dare and politely beat him over the head - uh, ask him to fix it.  Problem area 2) If the hammer seems OK, and you feel comfortable doing it, strip the bolt carrier and look for crud that might keep the firing pin from moving all the way forward when struck by the hammer.

My other gun a xm15 e2s sometimes will stovepipe with the round coming out of the mag. In otherwords the spent case is not ejected out the port before the fresh round from the mag. Is this a mag problem you think? I did use two diferent Bushy 10 round mags and had no problem but with a 20 round Adventure mag it would jam. I bought this gun new about a month ago and it jammed after every shot. Took it back to the dealer and he swapped out the bolt from a new Bushy that he had.   Any idea's? Can I rule out the extractor and ejector even though its only been shot less than 100 rounds?

Best advice for a complex problem:  call Bushmaster.  Good luck and welcome to the site.  Don't mind that testy cpermd guy, he hasn't been getting bran in his diet regularly.

shooter

I would suggest that you not tinker with it at all.  write bushmaster an email. then follow their directions and send it back.  I screwed around with mine and never could get it to function properly.  the factory will fix it so that you can run anything through it at any time without worrying about this or that.