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Discussion Starter · #1 ·
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
 

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Re: One type off ammo slam fires (so far)

I have had this issue only once [so far]. It was caused by soft primers in my buddys reloads. They work in his AK just fine.
 

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Re: One type off ammo slam fires (so far)

Sounds like they need a stiffer FP spring.
 

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Discussion Starter · #4 ·
Re: One type off ammo slam fires (so far)

[quote author=DSM link=topic=180.msg972#msg972 date=1286499349]
Sounds like they need a stiffer FP spring.
[/quote]

Agreed

That or redesign the firing pin to be a little lighter. The ACR firing pin compared to the AR or SCAR is a beast.

8)
 

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Re: One type of ammo slam fires (so far)

I had the same problem. You can read about my experience in the other thread. Contact Bushmaster and get it fixed.

The repair by the gunsmith at BM is detailed in my post. I am very happy with the service that they gave me. I am satisfied that I can no longer make my rifle slamfire with any type of ammo. And I put a great deal of effort into testing and insuring that the repair on my gun was successful. I really wanted to wring it out, and give it every opportunity to fail, but it is rock solid now.
 

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Discussion Starter · #6 ·
Re: One type of ammo slam fires (so far)

Thanks for the redirect. I have been following your posts in the other thread. I'm going to play with it for awhile, if it continues I will probably send it in fer a look over.

I was glad to see the conclusion was favorable in your original thread.
 

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Discussion Starter · #7 ·

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Re: One type of ammo slam fires (so far)

No slamfire issues with mine so far, fired a mix of a few hundred rounds of Win 55 grain NT, Win Ranger 60 grain PP, Win M855 and Federal 223A 55 grain FMJ.
 

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Discussion Starter · #9 ·
Well, I havent sent the rifle in yet, but I'll call this issue resovled at the moment since the recall is for the stated problem.

Called today and after 30min hold time, spoke with very nice person in CS. Took all info and said the fed-ex shipping label would be e-mailed the following day. Low and behold 1 hour after hanging up, I recieved the e-mail from fed-ex. Now I gotta pack it up and send it out. Hopefully go out NTL thurs.

Now the wait begins!! :)
 
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