removing stubborn pinned FSB - Page 1

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[ARCHIVED THREAD] - removing stubborn pinned FSB

Posted: 1/31/2016 9:14:05 PM EDT

So I have removed two BCM FSBs in the past and chopped them down to make low profile pinned gas blocks. I was working on removing my one on my latest BCM upper and those pins were stuck good. The previous two were hard to get out but with a second pair of hands they were able to removed. This third one was a PITA. I banged on that those pins and couldn't get them to budge. I soaked them in PB blast and went to work with a big punch and hammer. Is there any chance of bending the barrel slightly while doing this or damaging the barrel? I would think not but the amount of banging has me a bit concerned. I looked down the bore and it looks even all the way down but am just asking to see if it is even possible. I was using a 24 oz hammer. I just laid the upper receiver on my work bench and slide a piece of shelving under the barrel to help hold it still. Thanks

Posted: 1/31/2016 9:26:55 PM EDT

[#1]

You need to support it better, preferably with this. > Link.

They are currently out of stock at Aim but you can get them at R-GUNS as well.

It's also best to do this on a very solid bench but if you don't have that you should try pounding them out on a cement floor.

Posted: 1/31/2016 9:32:57 PM EDT

[#2]

If you swing and miss with the hammer, or the punch slides off, yeah you could damage the barrel. If you don't have the back of the FSB/barrel supported you could bend the barrel while you're whacking away at it (your piece of shelf probably filled this role). BCM puts those pins in with an arbor press at the factory IIRC, so they're not going to come out easy. If you have a hydraulic press or arbor press you could get them out a lot easier, but I'm guessing that you don't because you went the BFH method

. Nothing wrong with the BFH, it'll get the job done as well.

Posted: 1/31/2016 10:55:38 PM EDT

[#3]

I understand if i miss i could damage the barrel but i wasnt sure if they could literally bend from trying to remove them. The first two FSBs i removed were able to be removed with as much banging. Is there a way besides eyeballing to see if the barrel is bent?

For clarification i wasnt beating it like it waa trying to kill me but i was adding some force behind the swing.

Posted: 1/31/2016 11:08:40 PM EDT

[#4]

The proper tools make all the difference but cost is a factor. Considering how cheap low profile gas blocks are, you might be better cutting it off. Its not worth destroying your punches and potentially damaging a barrel

Posted: 1/31/2016 11:10:51 PM EDT

[#5]

True. I will probably get a press as i can affors and i do it enough. Is therw anyway to tell if barrel is bent? It looks straight

Posted: 2/1/2016 12:06:03 AM EDT

[#6]

I use the corner of the bench vise to press them out. Much easier than a BFH. Also press the pins back in with the vise.

If your going to cut down the tower, can't you just leave it on the barrel?

Posted: 2/1/2016 1:07:45 AM EDT

[#7]

I am pretty sure military armorers have special gauges that check for a bent barrel but I have no clue of any place that sells them.

Posted: 2/1/2016 1:08:25 AM EDT

[#8]

Quote History

Quoted:

True. I will probably get a press as i can affors and i do it enough. Is therw anyway to tell if barrel is bent? It looks straight

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suppressor alignment rod would work. If you can drop it through the barrel it's straight.

Posted: 2/1/2016 11:38:05 AM EDT

[#9]

I found some bore straightness gauges. What tolerance would be best, (-).001, .0001, .00005 ?

Posted: 2/1/2016 12:11:59 PM EDT

[#10]

I'd get the .001 unless you're building bench rest guns

Posted: 2/1/2016 1:10:35 PM EDT

[#11]

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Quoted:
I'd get the .001 unless you're building bench rest guns

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Thats what ill get then. It will be good to have anyways. The bore looks good from what i can tell. I see concentric circles when lookig down it but it will be nice to verify.

Posted: 2/1/2016 1:55:47 PM EDT

[#12]

I really had to work to get the taper pins out on my Delton. I have a couple pieces of advice:

First, the blow to the pin is only as effective as the solidness (is that a word) of the surface your barrel/FSB are sitting on. I used a 2" thick piece of plywood and set it directly on a concrete floor. This ensures that the force of the blows are not absorbed by the surface. Putting it on a workbench will absorb much of the force. I ensured the the rest of the barrel assembly was supported so that the barrel/FSB sat flush and flat on the board, with an overhang just barely enough to allow the pin to be clear of the backing board.

Second, use a way oversized punch to get it started. I had to use the largest punch I have coupled with a 2 lb sledge. I tried about ten blows and was about to give up when I decided to try a couple more. It finally broke free and I was home free after that.

I have this reassembled with no issues with barrel and no marring of the barrel or FSB.

Anyway, that's what worked for me. Now queue up the folks who'll tell me everything I did wrong....

Posted: 2/1/2016 2:08:32 PM EDT

[#13]

Quote History

Quoted:
I really had to work to get the taper pins out on my Delton. I have a couple pieces of advice:

First, the blow to the pin is only as effective as the solidness (is that a word) of the surface your barrel/FSB are sitting on. I used a 2" thick piece of plywood and set it directly on a concrete floor. This ensures that the force of the blows are not absorbed by the surface. Putting it on a workbench will absorb much of the force. I ensured the the rest of the barrel assembly was supported so that the barrel/FSB sat flush and flat on the board, with an overhang just barely enough to allow the pin to be clear of the backing board.

Second, use a way oversized punch to get it started. I had to use the largest punch I have coupled with a 2 lb sledge. I tried about ten blows and was about to give up when I decided to try a couple more. It finally broke free and I was home free after that.

I have this reassembled with no issues with barrel and no marring of the barrel or FSB.

Anyway, that's what worked for me. Now queue up the folks who'll tell me everything I did wrong....

View Quote

You did it wrong

Posted: 2/1/2016 2:34:14 PM EDT

[#14]

There is a gage called a barrel straightness gage. Gage is about 10 inches long, drop down bore, if it sticks then its bent. I've got two in the shop, one for 5.56 and other for 7.62.

On FSB that I remove I use a very large punch (12" long) and a 3lb ball peen hammer. I support the barrel on 2x4s, ie lay a 2' section of 2x4 vertical to my front and lay barrel pointing to the right, front sight away from me. Front handguard ring is off the 2x4 and barrel nut/Delta ring hanging off over the other 2x4. Now whack those pins. Colt taper pins are sometimes hard to remove too.

CD

Posted: 2/1/2016 3:25:49 PM EDT

[#15]

Quote History

Quoted:

There is a gage called a barrel straightness gage. Gage is about 10 inches long, drop down bore, if it sticks then its bent. I've got two in the shop, one for 5.56 and other for 7.62.

On FSB that I remove I use a very large punch (12" long) and a 3lb ball peen hammer. I support the barrel on 2x4s, ie lay a 2' section of 2x4 vertical to my front and lay barrel pointing to the right, front sight away from me. Front handguard ring is off the 2x4 and barrel nut/Delta ring hanging off over the other 2x4. Now whack those pins. Colt taper pins are sometimes hard to remove too.

CD

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Don't listen to this guy at all...it's not like he's got the creds to back it up

**that's complete sarcasm, Combat_Diver knows what he's talking about**

Posted: 2/1/2016 3:29:18 PM EDT

[#16]

Quote History

Quoted:
There is a gage called a barrel straightness gage. Gage is about 10 inches long, drop down bore, if it sticks then its bent. I've got two in the shop, one for 5.56 and other for 7.62.

On FSB that I remove I use a very large punch (12" long) and a 3lb ball peen hammer. I support the barrel on 2x4s, ie lay a 2' section of 2x4 vertical to my front and lay barrel pointing to the right, front sight away from me. Front handguard ring is off the 2x4 and barrel nut/Delta ring hanging off over the other 2x4. Now whack those pins. Colt taper pins are sometimes hard to remove too.

CD

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Getting gauge (6inch). It has been ordered.

Posted: 2/1/2016 11:14:48 PM EDT

[#17]

Quote History

Quoted:

You did it wrong

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Quote History

Quoted:

Quoted:
I really had to work to get the taper pins out on my Delton. I have a couple pieces of advice:

First, the blow to the pin is only as effective as the solidness (is that a word) of the surface your barrel/FSB are sitting on. I used a 2" thick piece of plywood and set it directly on a concrete floor. This ensures that the force of the blows are not absorbed by the surface. Putting it on a workbench will absorb much of the force. I ensured the the rest of the barrel assembly was supported so that the barrel/FSB sat flush and flat on the board, with an overhang just barely enough to allow the pin to be clear of the backing board.

Second, use a way oversized punch to get it started. I had to use the largest punch I have coupled with a 2 lb sledge. I tried about ten blows and was about to give up when I decided to try a couple more. It finally broke free and I was home free after that.

I have this reassembled with no issues with barrel and no marring of the barrel or FSB.

Anyway, that's what worked for me. Now queue up the folks who'll tell me everything I did wrong....

You did it wrong

Everything?

Posted: 2/1/2016 11:17:43 PM EDT

[#18]

THIS

I did mine last night . I used a 5/16 punch and a 20 ounce framing hammer. about 5 solid whacks on the first pin and 2 to get the second pin flush. I did it on a concrete floor using a Front sight bench block and a Upper receiver action block on its side to hold up the receiver end and I knelt on it to hold it steady.. You don't want it to move at all. You have to hit it sharply and hard directing all the force evenly on the pin.

Also I wrapped the Receiver and rail with a towel just in case.

Posted: 2/1/2016 11:36:39 PM EDT

[#19]

...

Posted: 2/1/2016 11:37:09 PM EDT

[#20]

...Damn internet

Posted: 2/2/2016 12:53:14 AM EDT

[#21]

Quote History

Quoted:
THIS

I did mine last night . I used a 5/16 punch and a 20 ounce framing hammer. about 5 solid whacks on the first pin and 2 to get the second pin flush. I did it on a concrete floor using a Front sight bench block and a Upper receiver action block on its side to hold up the receiver end and I knelt on it to hold it steady.. You don't want it to move at all. You have to hit it sharply and hard directing all the force evenly on the pin.

Also I wrapped the Receiver and rail with a towel just in case.

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I used those directions for the previous 2 i did. This third one was just a pain and took a lot more work than the others.

Posted: 2/2/2016 6:39:44 AM EDT

[#22]

When in doubt drill it out?

On a more serious note, I will echo a question above, if you plan to reinstall the gas block after removing the front sight assembly to make it low profile block why not just modify it on the barrel?

Posted: 2/2/2016 8:52:41 AM EDT

[#23]

Quote History

Quoted:
When in doubt drill it out?

On a more serious note, I will echo a question above, if you plan to reinstall the gas block after removing the front sight assembly to make it low profile block why not just modify it on the barrel?

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It is easier to grind on to get a good shape with it not on the barrel and tp remove the handfuard retaining cap that was on there. Like i said, the other ones i removed were not this stuck so i didnt think it would be such a pain.

Posted: 2/7/2016 5:21:42 PM EDT

[#24]

My gauge ahould be in this week. Besides having the barrel clean should i lube the gauge before inserting it in the barrel? Id imagine yes but i havent done this before

Posted: 2/7/2016 6:42:57 PM EDT

[#25]

Quote History

Quoted:
My gauge ahould be in this week. Besides having the barrel clean should i lube the gauge before inserting it in the barrel? Id imagine yes but i havent done this before

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Never lubed mine, just gave it a wipe to ensure no sand is on it. Damn sand gets into everything here.

CD

Posted: 2/7/2016 9:48:49 PM EDT

[#26]

Quote History

Quoted:
Never lubed mine, just gave it a wipe to ensure no sand is on it. Damn sand gets into everything here.

CD

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Quoted:

Quoted:

My gauge ahould be in this week. Besides having the barrel clean should i lube the gauge before inserting it in the barrel? Id imagine yes but i havent done this before

Never lubed mine, just gave it a wipe to ensure no sand is on it. Damn sand gets into everything here.

CD

Same, just wipe and drop through....or use a cleaning rod to push it out the way it went in if the barrel is bent

Posted: 2/19/2016 6:58:21 PM EDT

[#27]

Just wanted to report back. I checked all barrels i have removed the fsb the Bubba way with out a proper fsb base and all barrels are straight. The -.001 gauge dropped right through. Only contact was made at the beginning whem i initially dropped the gauge through the barrel. This was more than likely because the gauge was aligning itself. It is a tight fit so getting started square is a little tough. I have also since purchased a press to do this the right way going forward.