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Posted: 12/7/2007 8:00:01 AM EST
I have Bushmaster 16" std upper which bends the FP retaining pin after 100 rds.
Bushmaster said I need to replace the carrier to a modified M-16 type which covers
the FP & eliminates hammer contact under recoil. He said I could round the hammer &
I told him I had a JP in the lower. It is already rounded. I can't decern any contact
between the hammer & FP when manually cycling it. The disconnector holds the hammer down when the weapon cycles. I'm not firing hot ammo. I increased hammer
spring weight to see if that you slow the carrier down. I may have to add heavier buffer
next.
Any help would be appreciated.
Link Posted: 12/7/2007 10:23:33 AM EST
You need the shrouded carrier.
Link Posted: 12/7/2007 10:33:28 AM EST
Link Posted: 12/7/2007 10:59:22 AM EST
Sometimes the open carrier, even with a notched hammer, causes no trouble, and on some guns it does. You definitely need the shrouded carrier.
Link Posted: 12/7/2007 11:27:32 AM EST
Never had any trouble with my 2 bushmasters I bought back in 2000



Link Posted: 12/7/2007 11:29:49 AM EST
Thanks for the responses. It looks like a New BC.
Link Posted: 12/7/2007 11:30:06 AM EST
This is not just a Bushmaster issue. It is a general issue with all AR-15's with ramped bolt carriers and notched hammers.
Link Posted: 12/8/2007 9:18:59 AM EST
My Colt 6920 did it when it was brand new. I was one of the "unlucky" ones who got the old half circle carrier with mine. Changed out the pin after a couple hundred rounds. No problem ever since. Must have just needed breaking in. Never had this problem on my Bushmaster with the semi auto carrier.
Link Posted: 12/8/2007 11:17:36 AM EST
I have an upper that does this. I havent done it, but I think I can just modify the hammer instead of needing a new bolt carrier.
Link Posted: 12/8/2007 12:04:25 PM EST
When I look atr the channel that the firing pin retainer sits in, I can't help wondering how much it can deform.
Enough to cause real problems, or just something to keep an eye on in a preventative-maintenance-sort-of-way?
Link Posted: 12/9/2007 1:04:20 PM EST
[Last Edit: 12/9/2007 1:06:19 PM EST by shamayim]
Really strange that Bushie is telling you to spend your money on an enclosed rear area carrier, when it's the defect in the original product that's causing the problem.

They're correct.of of course. This issue ONLY arrises with the use of those goddamned cutaway carriers, which Colt instigated back in the '70s, and Bushie and nost wveryone else slavishly followed. It was NEVER a requirement of the ATFs---just yet another attempt by Colt to be politically correct. Colt has abandoned that cutaway, as has Rock River--but Bushie just keeps rolling along w/their out of spec pieces; plus having the balls to tell you, in their catalog, that if you don't use a carrier w/the cutaway, you're running an illegal part.

Was it me, I'd demand that Bushie replace the pin bending carrier.
Link Posted: 12/9/2007 7:19:10 PM EST
IIRC, current Bushie production has a shrouded firing pin but a shorter full circle at the rear of the carrier, so it 'can't trip an autosear' or some such malarkey.
Moon
Link Posted: 12/10/2007 3:02:22 AM EST

Originally Posted By halfmoonclip:
IIRC, current Bushie production has a shrouded firing pin but a shorter full circle at the rear of the carrier, so it 'can't trip an autosear' or some such malarkey.
Moon


Glad to see that Bushie finally got w/the program. Yeah, cutting back the underside of the carrier will keep it from being used for full auto, and I can understand why Bushie (and Rock River) would cover themselves in this way. But that makes it even more incomprhenesible why Bushie wouldn't just offer to swap him carriers.
Link Posted: 12/10/2007 4:16:01 AM EST
I don't really understand what is happenning with the half-circle and cutout BC's. I did have this problem with a DPMS upper. I changed the pin out for the old style one piece that looks kinda like a martini glass. No problems since then.
I also have a 16in Bushy that runs fine, the retaning pin looks fine also.
Link Posted: 12/17/2007 12:25:00 PM EST
[Last Edit: 12/17/2007 12:26:21 PM EST by war-wagon]
Colklink,
Over the weekend I swapped hammer to a rounded type & it still hangs up.
I previously had a jp & it hung up.

Cerberius,
I had a pin that deformed into a horseshoe after a couple hundred rounds. I did try
different types of pins without success.

Shamayim,
Bushmaster never offered a new BC, but informed me that they had switched to the type I need(shrouded). They definitely have a problem.
Link Posted: 12/17/2007 12:31:26 PM EST
I had the exact same problem, but with a standard AR hammer. If you do not fix it, eventually your FP retainer will snap and jam the BC in the upper in the middle of a 3-gun match (ask me how I know). I posted a "WTT my AR15 BC for your M16 BC" on the EE. I found a willing partner, and the deal only cost me shipping (~$5). The M16 carrier totally fixed the problem.
Link Posted: 12/17/2007 12:40:42 PM EST

Originally Posted By war-wagon:
Colklink,
Over the weekend I swapped hammer to a rounded type & it still hangs up.
I previously had a jp & it hung up.

Cerberius,
I had a pin that deformed into a horseshoe after a couple hundred rounds. I did try
different types of pins without success.

Shamayim,
Bushmaster never offered a new BC, but informed me that they had switched to the type I need(shrouded). They definitely have a problem.


Most likely they don't want to recall a bunch of rifles. However, if it is a design problem then I would insist they sent you a replacement free of charge.
Link Posted: 12/17/2007 12:42:13 PM EST
I bought a Bushmaster right after the sunset, and it had a shrouded firing pin.
Link Posted: 12/17/2007 12:54:28 PM EST
[Last Edit: 12/17/2007 12:55:52 PM EST by war-wagon]
I may give Bushmaster another call & see if they are willing to swap BC. Surprised he didn't offer one. At any rate I hate put another $79.00 into BC with the other one sitting on the shelf.
Link Posted: 12/17/2007 2:36:47 PM EST

Originally Posted By war-wagon:
Colklink,
Over the weekend I swapped hammer to a rounded type & it still hangs up.
I previously had a jp & it hung up
.

Cerberius,
I had a pin that deformed into a horseshoe after a couple hundred rounds. I did try
different types of pins without success.

Shamayim,
Bushmaster never offered a new BC, but informed me that they had switched to the type I need(shrouded). They definitely have a problem.


Now I have never had the hammer hang up on the bolt carrier, but I have an upper that bends firing pin retaining pins, and I noticed the top of the hammer ( its the type of hammer that is notched about 1/4" from the top ) is started to wear down at the start of the notch but I dont shoot the gun that often anymore. I bought a ton of retaining pins and have had to probably replace it every 500 rnds or so. I posted about it and was told to try first the rounded off hammer, then the shrouded bolt carrier if that didnt fix it.

Good luck.
Link Posted: 12/18/2007 7:40:02 AM EST
Colklink,

What happens with the hammer is when you release the disconector to reset the trigger
it drags the bottom of the BC. When it reaches the FP it pulls it against the retaining pin.
I marked the rounded hammer with black marker & cycled the action slow. The bolt carrier would lock back on the hammer as was apparent by the FP marks on the hammer. It appears to be a tolerence or timing issue because it doesn't do it in my other rifle. Either way I don't want a pin breaking going into the action at the wrong time. I'll try BM today.
Link Posted: 12/19/2007 11:39:25 AM EST
The non-shrouded carrier is a less than ideal design. However, for most folks it's easier and less expensive to simply have a few extra FP retaining pins handy and to swap them out as needed. $2.24 per 5 pack at Brownells. . I've been running a non-shrouded carrier than came with my 6721 and it functions great, despite heavy use. The carrier has ugly wear from hammer contact and I've lost count on how many FP's I have thrown away.

So, bottom line...If you have the option of getting a shrouded carrier over a non-shrouded one definitely go for it. But, don't get wound up thinking you blaster is automatically a turd without one.
Link Posted: 1/15/2008 11:10:35 AM EST
I called Bushmaster back & asked if they would swap the shrouded BC for the ramped.
They agreed to take care of it & sent me a postage label via email. A week later
I recieved the new BC & tested it. The firing pin retainer no longer bends & the carrier
is much smoother than the original. It seems to be larger in diameter from the key foward. Problem solved.
Link Posted: 1/15/2008 11:25:14 AM EST

Originally Posted By wreckdiver:
My Colt 6920 did it when it was brand new. I was one of the "unlucky" ones who got the old half circle carrier with mine. Changed out the pin after a couple hundred rounds. No problem ever since. Must have just needed breaking in. Never had this problem on my Bushmaster with the semi auto carrier.


Wow I have the seme exact rifle, carrier and problem. I replaced mine with no further problem after that just like you did but I will replace with a M16 bolt when i can find one at a good price. Good to see I wasn't the only one.
Link Posted: 1/15/2008 5:17:15 PM EST
Got a LMT BCG to replace the potentially troublesome one in a now departed Colt HBar. Now I keep it as a spare; it really saw few rounds, and after test hopping it in both rifles I put it away for a rainy day.
Glad the OP got great service from Bushie, but replacing the ramped carrier seems a thing worth doing, even if you have to pay for it.
Moon
Link Posted: 1/16/2008 7:49:57 AM EST
Glad to hear they took care of it for you. I will probably pickup a new bolt carrier for that upper eventually. Its a mutt M4 upper I built with a dpms carrier, bushy barrel and bolt.
Link Posted: 1/21/2008 7:04:54 AM EST
COLKLINK,

I inspected my other AR & FP retain pin looked ok. It must be tolerance issues between different rifles & parts. At any rate the non-ramped BC is the best.
Link Posted: 1/21/2008 7:46:05 AM EST
[Last Edit: 1/21/2008 7:46:27 AM EST by MW1831]
Can somebody post a picture of what the shrouded BCG looks like compared to the un-shrouded. I'm curious. This website is pretty good about great visual aids.... I was kind of surprised not to see one after reading this thread.
Link Posted: 1/21/2008 8:37:58 AM EST

Originally Posted By MW1831:
Can somebody post a picture of what the shrouded BCG looks like compared to the un-shrouded. I'm curious. This website is pretty good about great visual aids.... I was kind of surprised not to see one after reading this thread.


Ditto to the above, if someone would post pics I'd be grateful. I just bought a bunch of FP retaining pins for just this reason. I've got a DPMS carrier in a bushy upper...
Link Posted: 1/21/2008 8:52:01 AM EST
[Last Edit: 1/21/2008 9:06:00 AM EST by mike12345]
I just use the M16 carriers they wont bend retaining pins, have some extra weight to them, also I plan on getting a RDIAS later on so I wont have to buy new carriers to use with it.

If they dont issue me an M4 this deployment im going to bring my own parts and convert an A2 which wont be hard cause im the armorer.

The difference is





link sorry i stole your pics
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