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Posted: 7/17/2012 12:02:14 PM EDT
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I want to install a MK 12 Low Profile gas block on a barrel that currently has an A2 FSB.
What would I use to dimple the barrel for the LP GB screws? Thank you |
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I mounted mine on the barrel and use some flewuble wire to make sure I am over the gas port correctly and then tighten down with my hand and back a screw out and put a small amount of white paint on the tip and put it back in. Then repeat for the other screw remove the gas block and use a drill bit and just barely dimple the barrel.
But I lock the barrel in my vice between two piece of wood and have drill bit holder that keeps it from walking as well. That has worked for me but others will chime in with their input. I use to not demple but I had one work its self lose and now I always do. |
| How about a automatic center punch? They are inexpensive and very handy for other projects. It will give you a good "spot" for your center drill, also called spot drill, to pick up and stay on target. It may even fit through the set screw holes though the dimples it will create may make it hard to remove the block. Maybe someone here has used one and can comment. |
I like center punches and I know I know the barrel is HARD but I don't like to put pressure on a tube period especially one thats going to have a ton of pressure every time I make it go bang. Thats why I used the paint and stay method. You could probably do the same thing and then remove one screw and put a straw on the threads and dempel it that way as well. The straw is so you don't jack the threads up  electrical tape works for that as well.
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Quoted:
The barrel isn't hard. Posted Via AR15.Com Mobile True. A shallow dimple for a set screw to engage will not weaken your barrel. Look at how many sporting rifles are drilled and tapped for sights. You will not damage any threads using a automatic center punch. There is no need for straws or anything else. You simply push it down and it cocks and fires giving you a punch mark. As I stated before though, I don't know if it will fit inside the set screw holes to start with. Even if it don't I would mark the spots and use it. |
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Quoted: I like center punches and I know I know the barrel is HARD but I don't like to put pressure on a tube period especially one thats going to have a ton of pressure every time I make it go bang. Thats why I used the paint and stay method. You could probably do the same thing and then remove one screw and put a straw on the threads and dempel it that way as well. The straw is so you don't jack the threads up electrical tape works for that as well.You worry about using a spring loaded punch deforming the barrel yet you have no problem torquing down set screws?  FYI, neither will harm the barrel in any way. |
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Quoted:
Did this a couple of weeks ago. Tightening the set screws left nearly complete circular marks on the barrel...a light center punch in the center of the marks...followed by small dimples from a drill press. Worked well. Ding ding ding we have a winner. Joe |
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This page explains it very well. There are videos on that page too. I've seen a bunch of YouTube videos where people show how they dimpled their barrel. Most clamp their barrel in a vice and use a drill press just to ensure that they are drilling as steady as they can, as perpendicular to the barrel as possible and to ensure that they have as much control as possible too.
This type of punch would likely be ideal for finding the dead center within the set screw hole of the gas block. Just install the gas block onto the barrel, punch the center of one set screw and dimple it with a drill bit. |
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