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View Full Version : misaligned FSB issues with my A2


AJAX22
07-15-2007, 6:21 PM
I finally got to take my project A2 HBAR upper out to test, and it worked. sorta.... kinda.... not really.

The FSB was canted slightly which could be a result of any number of things (different manufacturers of barrel /FSB, previous owner screwing up the pin alignment on the barrel... etc.

As a result of the FSB being at a slight angle, the gas port was misaligned which in turn made it effectivly a bolt action that would cycle and eject once in a while but not consistantly. It was particularly irritating because it would cycle far enough to recock the hammer, and occasionally eject the brass, and once in a while pick up a new round and chamber it (which means that if you're counting on it not cycling you get to watch it eject live rounds into the dirt every so often)

So I'm now looking to either get the FSB/Barrel aligned, redrilled, and pinned by someone with more skills than myself.

or I can get an A2 FSB that attaches with allen screws (this would be my preference)

Where's a good place to get one of these, (I haven't actually seen one for sale, but with AR's if you can think of it, it probably exists somewhere). and once I find one what can I expect to pay for it.

One benifit of this happening is that I have definitly rethought the benifits of a straight pull AR, and I can state positivly that I will never own an AR configured as a bolt action rifle.

All the negatives aside, I have to say that one nice thing about the experiance was the MMG/ Bushmaster A2 stock combination that I had on it was wonderfully ergonomic. I've already converted all of my AR's to MMG's and I'm planing on building another 3 or 4 up (different bbl lengths, different cal. etc.) and they will all be getting a MMG.

If you know of a place to chase down the allen screw mount FSB (preferably with bayo-lug) please let me know.

Thanks

aplinker
07-15-2007, 6:31 PM
I finally got to take my project A2 HBAR upper out to test, and it worked. sorta.... kinda.... not really.

The FSB was canted slightly which could be a result of any number of things (different manufacturers of barrel /FSB, previous owner screwing up the pin alignment on the barrel... etc.

As a result of the FSB being at a slight angle, the gas port was misaligned which in turn made it effectivly a bolt action that would cycle and eject once in a while but not consistantly. It was particularly irritating because it would cycle far enough to recock the hammer, and occasionally eject the brass, and once in a while pick up a new round and chamber it (which means that if you're counting on it not cycling you get to watch it eject live rounds into the dirt every so often)

So I'm now looking to either get the FSB/Barrel aligned, redrilled, and pinned by someone with more skills than myself.

or I can get an A2 FSB that attaches with allen screws (this would be my preference)

Where's a good place to get one of these, (I haven't actually seen one for sale, but with AR's if you can think of it), it probably exists somewhere. and once I find one what can I expect to pay for it.

One benifit of this happening is that I have definitly rethought the benifits of a straight pull AR, and I can state positivly that I will never own an AR configured as a bolt action rifle.

All the negatives aside, I have to say that one nice thing about the experiance was the MMG/ Bushmaster A2 stock combination that I had on it was wonderfully ergonomic. I've already converted all of my AR's to MMG's and I'm planing on building another 3 or 4 up (different bbl lengths, different cal. etc.) and they will all be getting a MMG.

If you know of a place to chase down the allen screw mount FSB (preferably with bayo-lug) please let me know.

Thanks

Randall @ AR15barrels.com

He has these things in stock and can do the repair. He'd be able to do just about anything. Check his website. His prices are phenomenally reasonable and he's about 2 miles from you, IIRC.

He might be tough to get ahold of... He just might notice your thread, too.

AJAX22
07-15-2007, 7:08 PM
I sent Randall an e-mail.... got a form letter response... It looks like he's deffinitly the go to guy for barrel work in this neck of the woods, but It sounds like he's pretty booked up.

Any backup options in case he's too swamped?

ar15barrels
07-15-2007, 8:08 PM
The gas port on a 20" barrel will be around 0.093"
The gas hole in the bottom of an A2 front sight is around 0.125"
Your front sight would have to (literally) be 15 degrees to one side before you caused enough mis-alignment to affect function.
I propose that you look at the bolt carrier for a loose gas key or the gas tube for a missing gas tube roll pin and misaligned gas tube.

Bring or send it my way and it will be made right again.

AJAX22
07-15-2007, 8:22 PM
Thanks for the Response Randall.

PM on its way.

I love calguns

aplinker
07-15-2007, 10:17 PM
I sent Randall an e-mail.... got a form letter response... It looks like he's deffinitly the go to guy for barrel work in this neck of the woods, but It sounds like he's pretty booked up.

Any backup options in case he's too swamped?

He's great. Take your other builds with you. When you get there, you'll probably want to tweak them out, too. :D