Ferrule modification

With a unitized GC it is easy to mark the rear end of the cut inside the stock for the GC. Heck, you can do it with a non unitized front band and GC as well.

If you are going to glue the stock ferrule on, that should be done first. Some guys like to modify the stock ferrule before they glue it, others prefer to modify it after they glue it. Doesn't matter as long as the ferrule is modified and glued on. (On a NM rifle or Long Range rifle.)

Stick the unitized cylinder or front band and cylinder in the stock and push it up tight against the ferrule. Take a scribe or pencil and mark the end of the cylinder. Move the GC around so you get a line of marks on the bottom and up the sides of the barrel channel in the stock. Violla! You have the end of the cut necessary to clear the gas cylinder as it can not go back further than that. If you use shims between the barrel shoulder and unitzed cylinder, the cut will only be about .020-.030" behind the cylinder. When you place a 1/32" shim between the ferrule and front band during glass bedding (so those two parts don't rub in recoil), the cut will have PLENTY of room on a wood stock for the wood to "grow" or expand in moist seasons and not touch the rear of the cylinder.

When you have to build four brand new NM rifles from standard M14's in a week's time, you have to come up with ways to do everything FAST and correct the first time, so you don't have to go back and clear more. This is what I came up with to measure and cut this clearance the first time, every time. It is also what I taught my OJT's when I was the Instructor of OJT's at the RTE Shop (Apprenticeship Instructor).

The somewhat difficult part is to ensure the material you cut out of the stock is pretty flat and even all the way around the cut AND that the cut is perpedicular to the modified ferrule. It is easy to allow the cut to cut in too deeply in the wood at the back of the cut and you need to be VERY careful of that or the front of especially a wooden stock will be too weak.

Though I was never taught to do this, here's how I checked the cut as I was doing it. I found either a truly parallel smooth round file that was the same diameter all the way along the file OR a 6" steel rule was most helpful. I would place in the cut all the way around as I was working and look at it from the side and top/bottom of the stock to see the edge was perpendicular to the modified ferrule. If the file or rule was sloping downwards, that meant the cut was too high in back and I had to cut it down a bit. If the file or rule was sloping upwards, that meant the cut was too deep from perpendicular. Now, a little too deep is no problem, but by checking it like this as you work, it should keep you from cutting TOO deep at any point.

Before I became the Instructor of OJT's I actually learned to use my "calibrated" right thumb stuck in the cut behind the modified ferrule to ensure everything was good and that is faster still, but you only get to that point AFTER you have so cut a few dozen stocks.

These pics Art?


That is an excellent modification, I wonder who did it. Oh yeah, YOU!!!

This is a GI match stock ferrule. The one in the picture is a regular one that was modified. I don't see much difference if any at all. Second pic is the the same in the wrap with the stock number shown.


I can't draw a straight line. Think that saying this is not done to the drawing is true but it serves the same purpose. I don't see much difference between the two and it serves the purpose.