I build an AR10 from a PSA upper/lower set, and used a PSA bolt for a .308. I installed a Hiperfire trigger, because I love them. Went to the range. It wants to shoot full auto. First round fires, loads the second, fires, and then stovepipes on the third. I called PSA and the 'technical assistant' told me it might be the lower parts which weren't PSA, he called it a 'stacked tolerances problem.' He said it could be the safety switch. He said to buy a PSA lower parts kit. That was it. I installed the regular non full-auto two position safety, and can't understand why he said that. It's the trigger not the switch that's the problem, not getting the sear to fully engage the trigger when coming back I think? I was told at the range by someone that it could be a thousandths too small bolt underside that slides over the trigger, that it would take that little tolerance to go full auto. What? I used this trigger in another build and just transferred it, so I know it works in other rifles. What is the solution? What steps to take to figure this out? Thanks. Tom.
AR10 Solution Needed
- Thread starter writerman
- Start date
Coyotefurharvester
Silver $$ Contributor
Could be a dimensional problem with the trigger pin locations, or incorrect buffer/spring combination. Shooter part, pulling the trigger far enough for the connector to engage. Was a function test done after the lower was assembled?
anschuter2013
Gold $$ Contributor
Are you shooting off a bipod? The legs on some bipods can flex upon firing. When those legs return to their original forward position, the trigger is pulled into your trigger finger, and the rifle fires again, and again. Most of the time a maximum of 2 shots are inadvertently fired (3 total) before the rifle is out of position and the cycle ends. And then you change underwear.
It's definitely a tolerance staking issue of some sort. Start measuring the lower and trigger pin locations and hole size in the lower. Use dial calipers, micrometer and if possible pin gauges. Then measure everything on the trigger. Also measure the BCG and bolt. If that all checks out call the trigger manufacturer as well.
Had no bipod today. It was SO fast, it wasn't my finger I do not think.
Trigger, safety, bolt going in easily function tests always after a build.
Did that. Got a nice two stage. That Hiperfire trigger I was using, functioned fine in another rifle. I will install it in an AR15 instead now. We shall see! Thanks..
Yeah, got a nice two stage, installed it, we shall see now. I have had switching triggers problems before, just not so dramatic at two immediate shots, trying to go full auto. Thanks.
I think it's the elite, and I have the silver springs in it. They are the older version they no longer make, lighter trigger pull. I love the trigger, but swapped it out. It's going back into an AR15, because it worked fine in another one before. Thanks.
I did switch triggers with a brand new two stage I got today. We shall see. Thanks!
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