I just put together a Del-Ton 16" rifle kit, flat top, chrome lined barrel, standard bolt and carrier, standard lower parts kit and Spikes lower.  I took it out to the range yesterday and had about a 50% failure rate with the Federal bulk pack ammo I was using.  Some of the rounds fired the second time I ran them through but some of them didn't.  All of them showed what I thought to be a good firing pin strike on the primer.  The strike looked the same as the strikes on the primers of the rounds that fired.  The ammo was the Federal 100 round bulk pack Walmart sells for around $40.  I looked around and couldn't find any complaints about the ammo.  However a friend of mine had some old government surplus ammo that ran through almost 100%.  Before we went out I pulled the bolt and carrier, oiled it and ran a patch through the barrel.  Am I looking at an ammo problem or something with the gun itself?

Check and make sure your hammer spring is on correctly. Backwards installation is the usual cause of your problem. If it isn't that, make sure the FP channel is clean and everything else is sopping wet.

If you were getting solid primer strikes, the fastest way to see what the issue is would be testing some different ammo.

Like stated above, make sure the hammer spring is properly installed.

Are there some primers that are harder than others and tend to be harder to ignite?  I hadn't taken the bolt and carrier completely apart and cleaned it before I took it out so maybe the firing pin channel is the problem.  I'm quite sure my hammer spring is on correctly.  Thanks for the suggestions.

I've burned up about 5 of those wally world bulk federal packs in my homegrown ARmalite and never missed a lick. I'm using the JP yellow springs which are a good bit lighter than factory, so unless you got a bad batch, I'd bet something in the rifle, not the ammo. Anybody else have another rifle handy to test the ammo? We took a new 6.8 out last week and @ 40 degrees it was cold enough to solidify the Torco Super lube my buddy had in his bolt and slathered all over his firing pin. The gun absolutely would not fire until we stripped down and washed off the offending lube with some Rem oil and wiped everything down. Went boom boom boom after that though. The thick lube slowed down the strike enough to prevent ignition. I vote for sprngs or lube problem.....

Check out this post over in the Troubleshooting section.  I had the exact same symptoms with my first AR that was built by someone else.  Opened it up and compared it to these pictures and was surprised to see the hammer spring in backwards.

The gun will function check just fine with the spring backwards.  I would encourage you to double check it.

Let us know how you're making out.

-Ty

Thanks for all the help guys!  I took my rifle apart last night and the hammer spring was in backwards.  I haven't had a chance to shoot it again yet though.  The guy that helped me put the lower together has built quite a few of them but aparently we weren't paying close enough attention when we put the hammer spring on!  I found it interesting that some of the rounds would fire and some wouldn't.  My buddy had some older ammo that we put through and it fired 8 or 9 rounds without a hitch and misfired on the last one.  The Wally World ammo would fire three or four rounds and then misfire on three or four.  I'm betting the problems are solved with the hammer spring though.  Thanks again!