Hey Guys! I’m new to the forum, my wife and I just finished our AR's and are excited to be part of the community. I was hoping to get some help, I’m not new to AR's but this is my first build/own and I had some Jamming problems when we took them out.

Specs are:

Surplus Arms and Ammo lowers
Custom uppers w 16" free floating barrel, quad rail, flat top receivers. (Built by a good friend of ours that’s been doing it for years and owns his own tactical accessory company)
Magpul P mags

So my wife and I got threw 3 mags on each gun with no hiccups (disassembled them before taking them out and lubed the snot out of them with hoppes gun oil). When we both hit the 4th mags we started having brass not fully ejecting and spinning around in the receiver causing the next round and spent round to jam in the gun. Towards the end I started to have to use a set of pliers to get the spent round out of the gun, at that point we stopped.

So my thought is, is that they need to be broken in and the ammo was not perfect stuff (cant remember if they were reloads or new but they were slightly discolored on the brass). We took the guns home striped them both down saw nothing out of the ordinary so we cleaned, re-lubed and reassembled them.

Am I just being paranoid and this is fairly normal with new ar's? I know pistols have a break in so I wasn’t all THAT surprised, especially when they both started to do it at almost the same time.

Would bad / sticky ammo cause that? where should I start looking to fix it?

I did hear somewhere to use Grease instead of oil for the orings and the rails for the bolt. also why would it do it after almost 200rds instead of right away?

The oil burning off makes sense, we had all 6 mags loaded before we got there and after the initial sight in we started to have fun. After 3 mags each it was smokin a little. Then we loaded back up and got back to it, then the jamming started. Maybe I’ll try a different lube.

What type of ammo? We're you using the same type and lot number the entire time?

Run some good, full power ammo (XM193) through it and don't buy any gun show reloads.....ever.

If you are using hoppes oil, then chances are you are using hoppes cleaning solvent as well.

Stop that, and the problem of the rifles quickly foul choking out should end.

Bore of the barrel gets cleaned with something like Sweet copper solvent, since it cleans out copper fast, but better yet, does not leave behind a residue that collets fouling very quickly. As for the rest of the rifle to bolt clean and lube, including the clean the chamber and chamber brush by hand, CLP. If you need a source for CLP, then BreakfreeCLP in the large 16oz spray can.

Where CLP shines is that is has a cleaner in it, and will dissolve fouling down as it tries to collet. The Hoppes oil that you where using has no cleaner in it, so it just collect fouling, and once it burns off, left with just a sticky mess.

Granted that there may be other problems, but two rifle choking out about the same time/ same mag count is screaming a cleaning and lubing problem, with the wrong solvents being used.

I ordered some CLP today and it should be here in a few days. Ill go and shoot it again here soon and ill bring my cleaning kit with me. if it starts jamming again, ill squirt some oil down in it and see if it stops jamming. if it does than Ill know for a fact it was the lube or lack there of. if it continues ill know I got something else going on. Thanks for all the help guys I really really appreciate it! Thanks again!

I would also believe you got too much oil in chamber. After you clean chamber and barrel make sure to wipe out cleaner/oil out of chamber.take out bcg to lubit. If you want to spray some lube via ejection port don't get crazy with it and keep barrel pointed up so you dont get any in chamber. Lube in a warm chamber can cause extraction problems.