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1/22/2020 12:12:56 PM
Posted: 9/17/2009 7:53:20 PM EST
So, I'm installing a MEGA upper and a lightweight carbine handguard.

This WAS a post-ban Bushmaster Modular Carbine.

I CANNOT knock the gas block pins out to save my life. I have tried brass punches, steel punches of all different shapes and sizes.
All I have done is mar up the gas block, barrel and bend a shitload of brass punches. I read in the guides here that the author encountered a 20" Bushy that he absoluteltely could not get the pins out - he had to cut off the gas block. I am about there.
I am definitely knocking the small end through - the right side of the gas block has the big end of the pins on it.

Any idea? If I cannot get these out, I've gotta replace the whole block. Any recommendations on blocks? I'm obviously going to lose my perfectly good front sight if I go with a new block, as you can see from the pictures.

How the freak do I knock these pins out?!?!




These are new blocks/sights I'm thinking of:

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Link Posted: 9/17/2009 8:03:12 PM EST
I think your using the wrong size punch, And if you have tapered pins you are trying to tap them out from the wrong side.
Link Posted: 9/17/2009 8:33:15 PM EST
Originally Posted By nvhunter:
I think your using the wrong size punch, And if you have tapered pins you are trying to tap them out from the wrong side.


As stated, I have tried all different sizes of punches - the pins (small ends) are still sticking up above the surface of the gas block, so the size doesn't matter much - in fact the bigger the better, according to the guide on this forum.Once I get the pin to budge flush to the block surface, I would then use the smaller, correct size steel punch - I can't even get 'em to budge that far.
Link Posted: 9/17/2009 8:38:28 PM EST
Looks like you are punching in the right direction. The pins should come out the right side. I just took a new Bushmaster FSB off last weekend and I had to get out the air hammer to get the pins started. Good luck.
Link Posted: 9/17/2009 8:49:43 PM EST
left to right, same direction the brass ejects in....try sticking the whole thing in the freezer for a bit, get it nice and cold. metal contracts when cold, might give you the little bit you need.
Link Posted: 9/18/2009 6:13:37 AM EST
Ended up having to cut the damn gas block off - what a PITA - still working on it.

Never had pins so stuck in a gas block before.
Link Posted: 9/18/2009 5:48:03 PM EST
i use a great big steel punch to move em. yeah, sometimes it puts a mark on the fsb, but i bet its less of a mark then this ones got on it now!. once it budges, its easy with a brass drift. a little black paint in a pen and its macaroni.
Link Posted: 9/18/2009 7:09:12 PM EST
[Last Edit: 9/18/2009 7:14:34 PM EST by 240shwag]
A brass punch will not work. You need a hardened steel punch and the whole assembly cannot have any give when you hit it, it must be planted firmly.

I dont know why, but all the DIY threads dont specify the punch type. Use a hardened steel punch. Even a plain black steel punch will not work, you need it to be hardened so when you strike it, all of the hammers momentum transfers to the pins.
Link Posted: 9/18/2009 7:25:16 PM EST
The barrel wasnt parked under the FSB was it?
Link Posted: 9/18/2009 8:27:36 PM EST
Originally Posted By 240shwag:
A brass punch will not work. You need a hardened steel punch and the whole assembly cannot have any give when you hit it, it must be planted firmly.

I dont know why, but all the DIY threads dont specify the punch type. Use a hardened steel punch. Even a plain black steel punch will not work, you need it to be hardened so when you strike it, all of the hammers momentum transfers to the pins.


A big +1............also, you have to use something really solid on the back side......such as a piece of granite or steal plate w/ a socket against the back of the gas block where the pin would come out (no wood), hammer should be steal too.

Any give what so ever would render efforts useless, so dont do this on your bedroom floor (it gives)...........Use a really solid bench on the corner where the leg is or go all cro-magnon and use the garage floor.

You'd be suprised how little effort it takes w/ a solid system..........system being: hammer to punch to pin, gas block to socket to steal plate to garage floor, no give !!.............even a brass punch has give, so yea, use hardend steal.

Oh and my pins came out w/ a 4ounce hammer......I know, I was probably lucky
Link Posted: 9/19/2009 3:40:18 AM EST
Nail sets work nice to start them. Then once they move an allen wrench is good for the rest.

Oh well, while you have the Dremel out to cut that off, you could always flute it!
Link Posted: 9/19/2009 10:23:09 AM EST
I had the same problem not too long ago. I cut it off and bought a double rail gas block instead.

http://www.ar15.com/forums/topic.html?b=3&f=4&t=458804

After doing the FSB with my dremel, and then cutting the delta ring off the next day so I could blowtorch the stuck barrel nut, dremel fluting the barrel actually started looking quite doable.
Link Posted: 9/19/2009 11:24:22 AM EST
Originally Posted By Brahmzy:
Originally Posted By nvhunter:
I think your using the wrong size punch, And if you have tapered pins you are trying to tap them out from the wrong side.


As stated, I have tried all different sizes of punches - the pins (small ends) are still sticking up above the surface of the gas block, so the size doesn't matter much - in fact the bigger the better, according to the guide on this forum.Once I get the pin to budge flush to the block surface, I would then use the smaller, correct size steel punch - I can't even get 'em to budge that far.


Take a steel punch.......not a wimpy one........and cut it down.....close to the diameter of the pins...........concave it with a dremel tool to keep from slipping off the rounded head of the taper pin..........Lay it on the block like you have pictured and hit it hard...........don't give it a wimpy tap..............you need to bring out the big guns and whack the crap out of it...........it all else fails............cut on an angle into the pins witha cut-off wheel and dremel............................

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