Installing AR Front Sight block on a drilled barrel.

Jimro · January 9, 2013, 08:55 PM

I bought a used DCM legal Krieger barrel second hand, and the previous owner did not include a gas block.

I tried Sporter Express in Elizabethtown,KY, but the armorer their said that he couldn't do anything, and so now I'm thinking about the steps needed to fit a front sight block to a drilled and tapered barrel and still maintain a DCM legal appearance.

I wish I had a milling machine, because that would make this job a piece of cake. Unfortunately I don't, I have a drill press and normal set of hand tools.

Here is what I have so far.

First, measure the tapered holes in the barrel to see if they are parallel and record the dimension from the shoulder of the HBAR profile.

Second, index the new FSB onto the barrel and mark both using permanent marker.

Third, while the the FSB is indexed, use a marking awl to put a divot on the larger side.

Fourth, remove the FSB from the barrel, and drill into the side for the larger taper for both pins. This hole will be larger than the taper pin.

Fifth, put the FSB back on the barrel, indexed to our mark.

Sixth, drill through the FSB, use the taper reamer to cut the taper just a hair more, install taper pins. The thin end will mechanically lock the FSB in place.

Seventh, use a filling agent around the larger head of the pins for cosmetic uniformity. The filling agent can be pretty permanent since this is going to be a competition rifle, and the next time the FSB comes off it will be because the barrel is shot out (a few seasons down the road to be sure).

Are there any gunsmiths or machinists who see any problems with this plan?

Jimro

wyop · January 10, 2013, 01:33 AM

Well, you'll likely find that unless you use a center drill, using a twist drill will wander off your mark in a hurry.

You'll need to slow the drill press way down to use a reamer, and you'll need to flood it with cutting oil or other lube.

Doing these kinds of jobs on floppy machines usually begets poor results.

triggerman770 · January 11, 2013, 09:32 AM

Have you tried Kreiger? most gas blocks should fit it, as they are available in many diameters

January 9, 2013, 08:55 PM	#1
Jimro Senior Member Join Date: October 18, 2006 Posts: 7,097	Installing AR Front Sight block on a drilled barrel. I bought a used DCM legal Krieger barrel second hand, and the previous owner did not include a gas block. I tried Sporter Express in Elizabethtown,KY, but the armorer their said that he couldn't do anything, and so now I'm thinking about the steps needed to fit a front sight block to a drilled and tapered barrel and still maintain a DCM legal appearance. I wish I had a milling machine, because that would make this job a piece of cake. Unfortunately I don't, I have a drill press and normal set of hand tools. Here is what I have so far. First, measure the tapered holes in the barrel to see if they are parallel and record the dimension from the shoulder of the HBAR profile. Second, index the new FSB onto the barrel and mark both using permanent marker. Third, while the the FSB is indexed, use a marking awl to put a divot on the larger side. Fourth, remove the FSB from the barrel, and drill into the side for the larger taper for both pins. This hole will be larger than the taper pin. Fifth, put the FSB back on the barrel, indexed to our mark. Sixth, drill through the FSB, use the taper reamer to cut the taper just a hair more, install taper pins. The thin end will mechanically lock the FSB in place. Seventh, use a filling agent around the larger head of the pins for cosmetic uniformity. The filling agent can be pretty permanent since this is going to be a competition rifle, and the next time the FSB comes off it will be because the barrel is shot out (a few seasons down the road to be sure). Are there any gunsmiths or machinists who see any problems with this plan? Jimro __________________ Machine guns are awesome until you have to carry one.

January 11, 2013, 09:32 AM	#3
triggerman770 Senior Member Join Date: August 9, 2009 Location: Metro Atlanta Area Posts: 125	gas block Have you tried Kreiger? most gas blocks should fit it, as they are available in many diameters __________________ Small Arms Restoration, Inc. smallarmsrestoration.net Proud member of Georgia Carry.org www.georgiacarry.org

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January 10, 2013, 01:33 AM	#2
wyop Senior Member Join Date: July 15, 2012 Location: Wonderful, Windy Wyoming Posts: 133	Well, you'll likely find that unless you use a center drill, using a twist drill will wander off your mark in a hurry. You'll need to slow the drill press way down to use a reamer, and you'll need to flood it with cutting oil or other lube. Doing these kinds of jobs on floppy machines usually begets poor results.