CJW Posted June 3, 2014 Share Posted June 3, 2014 About a week ago, I was at the range with an AR—a recently assembled lower (had been zeroed and put through one match, so had maybe 100 to 150 rounds through it so far with no problems) and an upper that's been used for a while (a few thousand rounds). In each of three consecutive magazines (loaded to five rounds, I believe), the rifle doubled. That was all that was fired through it that day. So, it had been zeroed and shot at a match in that configuration without issue, and then it doubled three times in three consecutive magazines. What do I need to check out to fix this? Thanks! Link to comment Share on other sites More sharing options...
Paul Winters Posted June 3, 2014 Share Posted June 3, 2014 Check your hammer pin and trigger pin. Have seen this when the pin slips out of the receiver holes. There are aftermarket pins with clips to prevent this. Link to comment Share on other sites More sharing options...
Scott Steele Posted June 3, 2014 Share Posted June 3, 2014 Could be several things. Did you search this topic? I had it happen and found a lot of good information on this from way back. Hope you find and remedy the problem. Scott Link to comment Share on other sites More sharing options...
MarkCO Posted June 3, 2014 Share Posted June 3, 2014 Bump firing, doubling and slam firing are all different events and are caused by different things. Even those can be caused by different things. Link to comment Share on other sites More sharing options...
CJW Posted June 3, 2014 Author Share Posted June 3, 2014 Pulled the trigger once and got two rounds fired with the trigger still pinned back. I am pretty sure that means it was doubling, not bump firing. The trigger set up is a Timney, set screws tightened down, and KNS anti-walk pins that have not gone anywhere. Now, the doubles happened with 55gr Atlanta Arms .223, which is not what I had been using for the first bunch of rounds, so maybe it is a slam-fire/primer issue, though I've had no problems with that ammo in other rifles. I will try some of the other ammo and see if it happens again, or if it is limited to just the AA. Link to comment Share on other sites More sharing options...
MarkCO Posted June 3, 2014 Share Posted June 3, 2014 IF the primers from both the 1st and second round look the same, yep, it is likely the trigger. Send it back to Timney if you want to keep it and make them fix it. If the primers from the second have some wipes and look a tad hotter, then you are slam firing. Titanium firing pin, clip a coil from the buffer spring, take a weight out of the buffer are all potential fixes. Link to comment Share on other sites More sharing options...
Shooter115 Posted June 3, 2014 Share Posted June 3, 2014 Have you checked to see if the disconnector is functioning properly? Link to comment Share on other sites More sharing options...
HI5-O Posted June 3, 2014 Share Posted June 3, 2014 Have you checked to see if the disconnector is functioning properly? Sounds like the disconnector is not catching the hammer properly. Maybe worn hook or spring??? Link to comment Share on other sites More sharing options...
CJW Posted June 3, 2014 Author Share Posted June 3, 2014 IF the primers from both the 1st and second round look the same, yep, it is likely the trigger. Send it back to Timney if you want to keep it and make them fix it. If the primers from the second have some wipes and look a tad hotter, then you are slam firing. Titanium firing pin, clip a coil from the buffer spring, take a weight out of the buffer are all potential fixes. Thanks, Mark. Will do. As for the suggestions of wear, this was a brand new trigger a couple hundred rounds ago, so if there is a disconnector issue it is a defect and not a wear issue. Link to comment Share on other sites More sharing options...
MickB Posted June 3, 2014 Share Posted June 3, 2014 The Timney drop in trigger is designed to be used with the standard hammer and trigger pins. is it possible that you are using the oversize KNS pins which are throwing the trigger timing off? Mick Link to comment Share on other sites More sharing options...
Dwight Stearns Posted June 3, 2014 Share Posted June 3, 2014 I believe you are experiencing tolerance stack-up. I assume you have more than one ar. Try switching bcg's. A friend had the same issues a few years back. thinking it was the trigger he sent it back for testing (Ar Gold). The trigger speced out perfectly. Ronnin Coleman suggested the bcg swap. Cured the problem. It's worth a try. Dwight Link to comment Share on other sites More sharing options...
HRider Posted June 4, 2014 Share Posted June 4, 2014 As was mentioned earlier, check for slam firing. If the firing pin is bent slightly or very dirty and can't freely move inside of the bolt, it could cause slam firing. Hurley Link to comment Share on other sites More sharing options...
grouse Posted June 4, 2014 Share Posted June 4, 2014 Have you checked to see if the disconnector is functioning properly? Sounds like the disconnector is not catching the hammer properly. Maybe worn hook or spring??? I put money on this. Or installed backwards. Common mistake Link to comment Share on other sites More sharing options...
Towely Posted June 5, 2014 Share Posted June 5, 2014 My timney started doing this also, but after 5 years and about 5000 rounds. I have had different bolts running in it and it still does it on occasion. It did start happening after i changed it into another lower but i havnt really put any effort into finding out why as i dont use it much. Link to comment Share on other sites More sharing options...
Dwight Stearns Posted July 16, 2014 Share Posted July 16, 2014 Checking if you were able to work out the problem. Just curious. Link to comment Share on other sites More sharing options...
CJW Posted July 17, 2014 Author Share Posted July 17, 2014 Dwight, thanks for checking back on this thread. The gun in question actually is my g/f's. With a couple of recent big matches, we had to set it aside in favor of a working combo and have not had time to troubleshoot it yet. The first thing we are going to do is just run some of the AA 55gr and look at the primers to see if we are getting true doubles or slam fires. I would probably bet in terms of a slam fire since the trigger is pretty new and not showing issues with other ammo, but I could easily be wrong. The other ammo we tend to shoot is Hornady Steel Match, which has somewhat hard primers (I have had the occasional "click, no bang" with that in a couple of other rifles, so I am inferring harder primers), did not have the problem, which is another reason I think Mark may have called it right by suggesting a slam fire, but I won't know for sure until I can inspect some spent cases. I hope to have an actual answer soon! Maybe in a week or two. Link to comment Share on other sites More sharing options...
kurtm Posted July 17, 2014 Share Posted July 17, 2014 What causes an AR-15 to double? Why any good quality whiskeys when taken in a fair amount. Link to comment Share on other sites More sharing options...
Shooter115 Posted July 17, 2014 Share Posted July 17, 2014 What causes an AR-15 to double? Why any good quality whiskeys when taken in a fair amount. I try to put the guns away before getting to the point of not knowing which trigger is "the real one". I'm usually successful Link to comment Share on other sites More sharing options...
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