ar 15 burst fire unique problem VIDEO - Why not give your $.02

[kwheezy2000]

Hello,

I have a recurring problem with my rifle, every competition that I shoot there will be at least one instance of my rifle double, triple or more firing. I have tested my disconnecter while unloaded and I can not duplicate the hammer drop, I have tried several different disconnectors. The trigger assembly and lower parts kit are all dpms the cheapo set. The disconnector spring is installed correctly, fat side towards the trigger. I have no chattering on my bolt carrier

Youtube of disconnector working as intended? (turn up your sound if you can't hear the catch)

http://www.youtube.com/watch?v=wtxXQgNwPxE&feature=youtu.be

Now normally if the hammer follows the bolt for a slam fire it would drop out of battery and you would have to cock it (so I'm told); my weapon is fully in battery and ready to rock even after a burst fire, this is what really concerns me; I really would like to get this gun running right but I'm at a loss. I have about 6k plus rounds through it, but this gun has been doing this since I bought it in '10. This problem occurs with all different types of ammo, federal, american eagle, handloads, hornady, tula, you call it it will do it, I have tried loading hard primers and it does nothing. An estimate on the rate of occurence is about 2 or 3 times on average on 5 stages of about 28 round minimums, so maybe 150 - 200 rounds depending on how bad I am that day.

It's a bushmaster bolt & carrier, the whole upper came as a package, its the predator model; I have a bushmaster lower as well, DSA collapisble stock, with whatever buffer tube they come with; I would like to get into some regional shoots, and I highly doubt they will be as understanding as the local club shoots that I currently do. Now I don't really need a lecture on gun laws, the gun is malfunctioning, I know it's a problem but I have not been able to fix it and neither have the gun shops in my area.

Any help is appreciated, I tried to take pictures of my lower but my phone just doesn't cut it. I don't want to take this to barf15.com but if I can't get help here I don't know where to go, local sources have been depleted

If there are any other videos that would help tell me and I will make them

 

[1hobie]

Unfortunately I can't help you but don't fire the gun anymore. You have an illegal gun in the eyes of the BATF. You need an AR-15 experienced gunsmith.

Good luck to you.

Hobie

 

[kwheezy2000]

Benny Hill is in the same area as me, and behind La Rue he does quite a high volume of ar 15 work along with his 1911 business and he suggested today that I put a jp single stage trigger in; but I can't see how a 2.5 pound single stage trigger would alleviate the problem when I have a 6 pound stock single stage trigger with about 3/18" to 1/2" of creep; I really don't think its a bump fire.

I have taken this gun to three different gunsmiths, spent quite a bit of money and have seen no results, I'm just looking for some help; otherwise I will have to take my AK to the carbine matches; and I'm not really interested in doing that

 

[o Unforgiven o]

Hello,
I have tried several different disconnectors. The trigger assembly and lower parts kit are all dpms the cheapo set.

If you haven't already, I would suggest installing a new LPK and see if that resolved it.

 

[TurtlePhish]

It's the DPMS kit. They kinda suck. Get a better one and the problem will likely disappear. I'm surprised you manage to run competitions with it.

 

[kwheezy2000]

I don't throw them over the burm, and I do pretty quick double taps as is; that's how I avoid DQ's; I would consider changing out The LPK, but I'm on the 2nd one already, and I had this one professionally installed. DPMS and Bushmaster are the same company I can't see that they wouldn't work, I haven't heard any issues like this with a DPMS kit, As I understand it most of the LPK are about equal. I will have to borrow someone elses lower and see what happens

 

[TurtlePhish]

It doesn't matter how professionally the kit was installed, DPMS kits are frequently out of spec and have issues. A higher quality kit now will save you the cost of replacements in the future, even if it might be more expensive in the short-term. Higher quality kits will also have better triggers and be more reliable, which is definitely a plus for competition.

 

[kwheezy2000]

If that is the case, what manufacturer would you reccomend, I would rather buy the parts individually as I don't need the springs, trigger guard, mag release, bolt catch, safety selector or grip... unless the subcontracted springs are no good.

You will have to excuse the what for and why is, I just like to know what I'm throwing money at.

 

[TurtlePhish]

I had a whole Spike's Tactical Enhanced LPK in my AR, and it was great. The parts are Nickel Boron coated- some may say it's a gimmick, but the trigger definitely feels better than a milspec kit and it's very well made. I'm sure there's a way to get just FCG components, but if you bought the whole kit it couldn't hurt to have spares of all your lower components.

 

[kwheezy2000]

As I understand it boron nickel is much slicker than a mil-spec coating (I have no idea what dpms uses, I'm sure it's cheap); with a slicker coating would this not defeat the purpose? I assume that the disconnector is slipping as this is the intended part to defeat a burst fire, Could my FCG pins be drilled be out of measurement that would lead to this problem? Like I said I have tried multiple dpms disconnectors because I assumed that dpms and bushmaster parts should line up being as they get their lowers from the same manufacturer and you would not see these same results from a factory gun, even though I have tried to mimick a factory gun from scratch

 

[Sky]

I had a double popping AR once and the company sent me a new trigger assembly; my problem was solved with no further problems. It only takes a tad bit of aggression/polishing during the finishing process to make them double ( or more ) pop.

 

[TurtlePhish]

As I understand it boron nickel is much slicker than a mil-spec coating (I have no idea what dpms uses, I'm sure it's cheap); with a slicker coating would this not defeat the purpose? I assume that the disconnector is slipping as this is the intended part to defeat a burst fire

It'll work perfectly, the disconnector won't slip at all. The main purpose of the coating is wear resistance and eliminating grittiness in the trigger pull.

 

[madcratebuilder]

I have put 2 DPMS LPK in this gun, the last time was by a reputable gunsmith,

If you can rule out bump fire then it has to be the FCG. The DPMS LPK's are not the most reliable. I would install a FCG from G&R.

The G&R kits are the best quality parts. I believe the FCG's are from LMT. Another choice would be a two stage LPK from ArmaLite if you like a two stage trigger. If you want to keep it single stage the regular LPK from ArmaLite would be GTG.

 

[MtnCreek]

Could my FCG pins be drilled be out of measurement that would lead to this problem?

Possibly. If you’ve already swapped fcg’s, I would measure the holes and spacing and compare to spec (spec’s can be had from ar15com’s site) prior to buying more parts. Sounds like hammer / trigger engagement issue to me; that will cause the exact problem you’re talking about.

Keep your records on getting it fixed (smith & parts invoices) just in case this thing malfunctions around the wrong crowd. I would get it fixed before shooting more comps w/ it.