missfires with new s&w ar 15

[possumpacker]

mounted a scope and went to sight in the new rifle with some black hills ammo. everythings fine in fact its makin 1" at 100. I switch to some reloads an click. misfires several tines. took the to a reputable gun smith my reloads fit chamber guage. he trys his reloads and some factory stuff gun runs fine. I buy some win. 223 varmentX gun loves it and runs fine. so I think its my reloads and buy some American ammo 55gr. the 90 packs click, missfire. im standing at my range pissin an moanin when my brother pulls up , I tell him whats going on, he hands me a mag with some good factory ammo they been coyote huntin with and gun goes click. all of the ammo that misfired had very lite mark on the primer. I put the win ammo back in and bang bang. what up.

 

[padawan]

It sounds like a light primer strike. Does it have a stock trigger? Has someone changed the hammer spring to a lighter weight? Try a heavier and/or stock hammer spring. Does the firing pin move freely in the bolt? Take the bolt out, firing pin out, clean it and reassemble. Try a new/different firing pin. Some run "JP Yellows" lighter spring set and you can get light primer strikes/misfires with hard primers.

Someone else will chime in...

 

[Wild Deuce]

*

 

[red_zr24x4]

Primers not seated completely, the first hammer strike or two are seating the primer then they will (usually) go off.
That's my guess.

 

[sig1473]

Backwards hammer spring. Just a guess

 

[possumpacker]

thanks, ill take the firing pin and spring apart and clean it good. gun is stock out of the box and does it with store bought ammo and reloads, the winchester ammo that works may have softer primer.

 

[boogieman]

I would pull the bolt apart and clean and check the firing pin first. It kind of sounds like you are binding up a little.

 

[SEIndSAM]

I would pull the bolt apart and clean and check the firing pin first. It kind of sounds like you are binding up a little.

^^^^^^ This. May be some Mfg crap in the firing pin channel. Then, double check the hammer spring and make sure it wasn't installed backwards.

 

[red_zr24x4]

OP in your first post it only did it with reloads, primers not fully seated.
Later you state doing it with everything, possibly hammer spring or gunk in the BCG

 

[Stang51d]

I have only ever had one time that an AR had light strikes, and that was one chambered in 5.45x39, and the surplus stuff has real hard primers. I changed the spring and it never missed a lick. But hard primers isn't your problem. These guys make some good calls, I think you are on the right track.

 

[possumpacker]

just got the AR running. installed a 3lb timmney trigger and no more misfire so either hammer spring was weak or backwards. I had planned on an after market trigger before I bought the rifle so not a big deal. so thanks for pointing me in the right direction. oh and the gun shoots sub MOA now.