Hello. all.

I'm new to the ar15 so I'm not sure if this is a big deal or what.  Today (and one other occasion) my rifle had two rounds shoot off for a single trigger pull(i think this is called a slam fire).  I'm not sure if more rounds would have fired since on both occasions they were the last two rounds in the mag.  In the past three times i went shooting, this happened twice.  However, it only happened once during the course of the day and didn't happen at all after(happened once on day 1 and once on day 3.  worked fine on day 2).  I bought the rifle used from a friend(less than 1000 rounds through it).  It is a Bushmaster Varmint Special.  I'm wondering if anyone can tell me what could be wrong or if i need to get new parts.  I try to clean the rifle as well as I can after every trip to the range and i dissassemble the bolt, firingpin etc, to get them clean also.  

I also have a slight problem with the two stage trigger.  it seems to be a little sticky.  After shooting a round, it will sometimes not reset all the way and will be stuck at the second stage.  even when the gun is unloaded and i try using a snap cap, the trigger will sometimes get stuck after the first stage and not return to its normal position.  I've tried to oil the trigger parts inside the lower but perhaps there are other things i should be doing?  Please remember that I am fairly new to the AR15 and I may not be all that familiar with everything.

so any input is welcome.  thanks in advance guys.

Welcome to the forums and to the AR15 rifle community.

Sounds like your rifle is "doubling".  A problem with the disconnector in the FCG (fire control group).  I am no certainly no expert, but I can point you in the right direction.  For future reference please check the FAQ's at the top of the troubleshooting forums.  

Look here under "doubling/FCG" for starters.

Someone will be along shortly I think that may be able to offer you more expert advice.

best of luck.

Get Bushmaster on the phone, ship it back, my new a2 did the same thing.  Replaced the disconnector for free. Took a week to get there  received it on a Monday replaced and shipped back out the same day! You only have to pay shipping to them which was 20 bucks for standard ups shipping, that includes the local mail room company packaging et cetera and insurance to cover the cost of the lower. Just be sure to speak with the manager of the business (if you plan to have them package it and ship it for you), so they know whats goin on, I spoke with a guy who said he was and some customers were a little startled by the lower receiver. Even tho im not exactly sure what they expected me to do with half a rifle and no magazine.

Thanks for the replies.

Well bad news, the A2 i shipped back is still doing it. But still only with wolf ammo. Bushmaster said they replaced the disconnector, but still first round is fine, every round after that 2rnd burst. Tweak any input? is this just poss a ammo related issue  even tho i dont see how it could cause this tho i am gettin light primer strikes and during these the trigger isnt resetting.

thats what i figured, but wouldnt this be caused by all ammo and not just wolf?  i could be wrong but could it be possible that the wolf is weak loaded and not enough to push the hammer all the back onto the disconnector but enough to cycle a round?     im lost especially since i sent it back to bushmaster and they said it was the disconnector. tomorrow im gonna take some better ammo and see if i can do it with winchester,remington and some olympic m193.

Heavy Metal or Tweak, I did the function check as per the military manual I have. Where you hold the trigger pull the charging handle with the trigger down they said you should hear the disconnector release the hammer, mine does not. If I do not hold the trigger down it will function as it should, if I seperate the upper from the lower and push the hammer down with my finger while holding the trigger the disconnector catches it as it should then releases it normally when i let go and if i do not hold the trigger it is caught normally, does this help in either you possibly helping me with my problem?  And after seeing this anything with the upper that can cause this?

Instead of sending it back to Bushmaster I am gonna buy entire new FCG, MidwayUSA has a DPMS Mil Spec package with hammer,trigger,disconnector,selector switch. If that doesn't fix the problem then it has to be something I am doing when firing the rifle.