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Posted: 11/16/2016 10:07:55 AM EDT
| I've picked up a very nice Colt VP 12 barrel, however the FSB does have a small amount of movement, What would be the easiest way to tighten the FSB up to have it secured tightly to the barrel? |
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Normal repair would be to just hammer the taper pins in deeper. Use a brass punch or brass rod so you don't mar up the finish. Best if you use a front sight block available from many sources to hold and secure the FSB while doing it. If you don't have one, just be sure to support under the FSB to prevent any damage.
If you want to borrow an FSB block, I can lend you mine,you just pay shipping both ways. 
Or>>>>http://www.brownells.com/gunsmith-tools-supplies/rifle-tools/sight-tools/ar-15-front-sight-bench-block-prod20727.aspx |
One Crude way is to remove the fsb and knurl the barrel  reintalled fsb and drive pins in it wont show on the outside.some oversized pins will help too but then u have to ream the fsb some.
 photo4 by sergio izquierdo, on Flickr
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Quoted:
Normal repair would be to just hammer the taper pins in deeper. Use a brass punch or brass rod so you don't mar up the finish. Best if you use a front sight block available from many sources to hold and secure the FSB while doing it. If you don't have one, just be sure to support under the FSB to prevent any damage. If you want to borrow an FSB block, I can lend you mine,you just pay shipping both ways.
Or>>>>http://www.brownells.com/gunsmith-tools-supplies/rifle-tools/sight-tools/ar-15-front-sight-bench-block-prod20727.aspx On the other hand I can trade you a nice cmpb barrel that is way better than that obsolete barrel with the loose cast FSB. Lol. I won't even charge you and all your problems will be solved. 
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Thanks for all the advise and the offer to relieve me of this troublesome problematic barrel. I like the ideal of knurling, I just don't know how to go about it. The pins are currently driving all the way in but it still has an ever so slight wiggle and I'm not wanting to over drive the pins..... It's not bad and I've thought about leaving it alone, I just have a slight touch of OCD. If I can fix with out a great deal of effort, then I'd like go ahead and fix.
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Think I'd start with a new set of pins as stated or invest in a set of oversized pins if necessary. Brownells used to carry them and DPMS sold them. Hint! Last BCM pins I purchased were a little out of spec on the large side. Generally oversized pin is a little longer with same 2-0 taper if memory serves. Might not have to purchase a reamer since holes are already too large for the existing pins. Generally a trim on small end of pin might be necessary if being standard retro anal. Kinda depends on how much or little it sticks out once pin is installed. If reamer is necessary use with caution as a little goes a long way.
Shouldn't be a difficult repair. |
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The problem is usually caused by a barrel that is just a tad small and then the pins will not take up the play. Think about it, even with over size pins they still wedge 360 deg and do not pull the FSB down against the barrel. If the pins had straight sides and were oriented vertical like a wedge they would pull it down, but round pins do not. Believe me, I found out the hard way!
The solution is to take the pins out and clamp the FSB down against the barrel while it is fixture in the correct alignment. Ream the holes slightly, then reset the pins. If the pins go in too far either look for slightly larger pins ( a couple thou at the head makes a big difference) or use larger pins. I have longer pins that I can drive in and shorten both sides to the correct length. I have a small C-clamp set up for just this purpose and I use it if the FSB is at all loose on the barrel. No more loose FSBs. |
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