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Has anyone out there had a particular brand of ammo result in occasional slam fires?
I came upon 200 rounds of Winchester Ranger brand .223 55grn PSP (Model# RA223R) So off to the range I went. Was sighting in a 3x scope on the ACR so I did initial sighting with Walmart federal. No problems. Them I do the fine tuning with the Ranger ammo. Safety on, Release BCG and BOOM. The chambered round pops. I start shooting whats left in the mag and get a double tap. Shooting WWFederal again and no other issues that range session.
Next time to the range, I was sighting a 2 x 10 scope. Same deal as above, this time I had 60 rounds of the ranger with me. Round would go off on closing bolt (not everytime) and occasional double taps. So i'm thinking got a disconneter issue. Being the only one on the range. I experimented with different types of ammo.
Win White box, LC M855, Federal XM193, PMC Bronze, Wally world Federal and the above ranger. Only the ranger would slam fire. All the other functioned as they should.
So I go home and give the rascal a good looking over. No issues found at all. Everything functioned checked normal and I found no broken parts.
I did a little more investigating and realised that the firing pin on the ACR is a beast compared to the AR or SCAR. Now I understand why the firing pin spring is there. The BCG is very heavy and creates alot of momentum upon slamming shut, imparting that energy on the firing pin. (Just like the occupents of a car continue forward when the car stops suddenly after hitting something)
The rifle does not fire out of battery, all fuctions are normal. I have never examined a round without firing it after being chambered to check for dimples on the primer. That'll be for next range session to test my theories.
So far only one brand of ammo is allowing for slam fires. I think it's a combo of very soft primers and a very heavy firing pin. I dont think the FCG is suspect in this case.
Public safety message: ALWAYS POINT YOU MUZZLE IN A SAFE DIRECTION, ESPECIALLY WHEN CHAMBERING A ROUND!!
10/18/2010 update; see last post
I came upon 200 rounds of Winchester Ranger brand .223 55grn PSP (Model# RA223R) So off to the range I went. Was sighting in a 3x scope on the ACR so I did initial sighting with Walmart federal. No problems. Them I do the fine tuning with the Ranger ammo. Safety on, Release BCG and BOOM. The chambered round pops. I start shooting whats left in the mag and get a double tap. Shooting WWFederal again and no other issues that range session.
Next time to the range, I was sighting a 2 x 10 scope. Same deal as above, this time I had 60 rounds of the ranger with me. Round would go off on closing bolt (not everytime) and occasional double taps. So i'm thinking got a disconneter issue. Being the only one on the range. I experimented with different types of ammo.
Win White box, LC M855, Federal XM193, PMC Bronze, Wally world Federal and the above ranger. Only the ranger would slam fire. All the other functioned as they should.
So I go home and give the rascal a good looking over. No issues found at all. Everything functioned checked normal and I found no broken parts.
I did a little more investigating and realised that the firing pin on the ACR is a beast compared to the AR or SCAR. Now I understand why the firing pin spring is there. The BCG is very heavy and creates alot of momentum upon slamming shut, imparting that energy on the firing pin. (Just like the occupents of a car continue forward when the car stops suddenly after hitting something)
The rifle does not fire out of battery, all fuctions are normal. I have never examined a round without firing it after being chambered to check for dimples on the primer. That'll be for next range session to test my theories.
So far only one brand of ammo is allowing for slam fires. I think it's a combo of very soft primers and a very heavy firing pin. I dont think the FCG is suspect in this case.
Public safety message: ALWAYS POINT YOU MUZZLE IN A SAFE DIRECTION, ESPECIALLY WHEN CHAMBERING A ROUND!!
10/18/2010 update; see last post
