I need some advice on a repair I'm doing for my brother in law. He purchased a S&W Sport 2 a while back and decided to add a BCM KMR. When he installed the low profile gas block, he neglected to use thread lock or secure the set screws... This is the result after a few FTF's:



The bolt carrier key deformed and will no longer seat on the gas tube (which I also replaced).



I will be dimpling the barrel today with my jig from Rainier Arms. My question is if I should bother to dimple the barrel where the A2 front sight was pinned, or just use thread lock?

Looks like you will only need a new gas key, as far as dimpling it is pretty easy, I normally just put the gas block on and mark through the screw holes with a small bit, then take the gas block off and dimple with the proper sized drill bit on my drill press, the dimple does not need to be very deep.

Thanks for the response, Dave. If you look at the last picture, the hole on the left side of the jig is half on the barrel and half off where the old A2 front sight was pinned. Just create a small dimple there you think?

I'm sure your fine with 1 dimple only

It would be more secure to just shave the FSB and use the taper pins.

1 dimple will be fine, I use a cupped screw and a bit of loctite and it will hold with no problems at all.

 
That's what I would reccomend as well.  If he's set on using the gas block, one dimple is all you need.