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1/25/2018 7:38:29 AM
Posted: 9/7/2010 9:42:44 PM EST
I know this has been discussed here several times, for some reason I don't get a long too well with the search feature, so I thought I'd ask again, sorry to repeat this.

So I have a CMMG A1 profile mid-length, which needs the end cap changed from the circular to triangular shaped type, I would prefer to do it myself as I have most of the necessary tools.

However, it's been mentioned here that with heating the FSB and barrel, with a torch, will expand the metal in which to easily drive out the taper pins.

Now that all sounds simple enough, but it was mentioned there is some solution, whether it was a spray, jelly, etc that is applied to the area and I'm not quite sure if it just keeps the heat to the area where this solution is applied or where it's applied on either side, sorry if I'm not making sense as I want to ensure I totally understand this before I I attempt just to ensure I do it correctly.

So what was or is the name of this solution or material I put on the barrel to control the heat when I heat it up with the torch?

And where can one obtain this material, can I obtain it at a place like Home Depot or Lowes, or must it be purchased at a place that sells welding supplies?

I appreciate all the help my friends, cheers,


Link Posted: 9/8/2010 12:05:00 AM EST
If your FSB isn't rusted onto your barrel, it shouldn't be too hard too remove. My local gun shop removed my FSB with a heat gun and a hammer after rust formed between it and the barrel. I didn't get to see it because they took it behind a wall into their little repair shop, but they did tell me they used a heat gun with quite a few whacks from a large hammer (of which I heard every one, and cringed each time).
Link Posted: 9/8/2010 1:34:39 AM EST
I personally don't like to use heat exept as a last resort.What I have done is used PB Blaster penetrating oil.For 2 stubborn FSBs,I broke the ends of a Q-Tip off,took them and layed them on the tapered pins and just kept them soaked spraying when it looked like the oil was drying or disappating.Did this 2 days.Then taped out the pins.And just a reminder,them pins are wide on the right side,so need to be taped from left to right to remove.Good luck.
Link Posted: 9/8/2010 5:19:55 AM EST
[Last Edit: 9/8/2010 5:21:13 AM EST by MarkRSims]
I had a CMMG barrel a while back with a FSB whose pins refused to budge. I ended up drilling them and destroying the pins.

One thing I've learned about these, having the front sight base mounted securely in a vise, and rapping solidly on the pins with a good punch (or one of those nail setting punches with the cupped end) and a heavy enough hammer usually gets them out in one shot. But the key is SECURELY mounted, and smack 'em hard once.

If you can't get them out, I'd suggest soaking them in oil for a couple of days, then taking the barrel over to a local machine shop and having them press the pins out.

Don't try and hold everything in your lap and have it moving all over the place. Oh, and wrap your FSB in electrical tape to prevent the vise jaws from marring.
Link Posted: 9/8/2010 6:47:20 AM EST
[Last Edit: 9/8/2010 6:48:51 AM EST by hk45shooter]
Kroil is what I use for stubborn FSB's, or anything else for that matter. I got mine at a local machine shop, so I don't know how readily available it is in normal stores.

ETA: I don't use it to control heat, just as a penetrating oil.
Link Posted: 9/8/2010 4:45:07 PM EST
Kroil or AeroKroil. let it soak for a couple days.
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