A little over a year ago, I posted here that I had an AR5 lower with a Wilson TTU trigger group that "bump fired": one trigger pull, 2 rounds fired. The upper on the rifle was a 6.8 SPC2 firing higher-pressure "tactical" loads.
Shortly thereafter, for entirely other reasons, I sold the 6.8 upper and have continued to use the lower with a few 5.56 uppers, no problems at all.
A few months ago, I finally put together and began breaking in a 40-cal upper, it is recoil-operated. Break-in was uneventful, and it has had a few hundred more rounds down the tube since then.
On its last trip to the range, it bump-fired: one pull, 3 rounds. It didn't do it every pull, but it did it. I handed the rifle to a friend who fired a few rounds then got a 5-shot burst.
Needless to say (since the SBR lower is not a Form4 full auto) this is disconcerting.
It seems the recoil from the higher-recoil calibers (and the recoil from a recoil-operated upper) is sufficient to trip the sear. Other thoughts?
When I posted on this back the fist time, a few said sometimes TTU's go full-auto when worn out. The trigger has definitely been well used, but shouldn't be anywhere near worn out - and this only happens with non-5.56 uppers.
I am not a newbie, I am not being bitch-slapped by recoil. I understand a smooth rearward pull and a good follow-through. I am riding the sear and only letting off enough slack to reset.
Thoughts?
My plan is to take the TTU out and replace with something else and see if this solves the problem. I do want to know if the TTU is more "recoil-shock sensitive" as that will dictate which guns it does NOT go in, now and in the future.
Shortly thereafter, for entirely other reasons, I sold the 6.8 upper and have continued to use the lower with a few 5.56 uppers, no problems at all.
A few months ago, I finally put together and began breaking in a 40-cal upper, it is recoil-operated. Break-in was uneventful, and it has had a few hundred more rounds down the tube since then.
On its last trip to the range, it bump-fired: one pull, 3 rounds. It didn't do it every pull, but it did it. I handed the rifle to a friend who fired a few rounds then got a 5-shot burst.
Needless to say (since the SBR lower is not a Form4 full auto) this is disconcerting.
It seems the recoil from the higher-recoil calibers (and the recoil from a recoil-operated upper) is sufficient to trip the sear. Other thoughts?
When I posted on this back the fist time, a few said sometimes TTU's go full-auto when worn out. The trigger has definitely been well used, but shouldn't be anywhere near worn out - and this only happens with non-5.56 uppers.
I am not a newbie, I am not being bitch-slapped by recoil. I understand a smooth rearward pull and a good follow-through. I am riding the sear and only letting off enough slack to reset.
Thoughts?
My plan is to take the TTU out and replace with something else and see if this solves the problem. I do want to know if the TTU is more "recoil-shock sensitive" as that will dictate which guns it does NOT go in, now and in the future.
