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Gunsmithing Opening stock barrel channel inlets

BurnOut

DDOJSIOC
Full Member
Minuteman
Nov 24, 2013
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Dallas
So, because I evidently like to do things the difficult way, I have a habit of buying either unique rifles for which there are few options in aftermarket stocks (which usually means Boyd's), or buying stocks that don't have the right barrel inlet for what I have (a Stocky's Long Range Target stock for an M24-barrelled R700), I have found myself in the position of needing to open up a number of stock barrel channels over the years. I have tried a variety of approaches, some with more success than others (JUST SAY NO to the Dremel). One thing that has always vexed me is how, with no more than basic/common tools, to best open up a barrel channel for a tapered barrel without having an excessively large gap between the stock and the barrel once the barrel narrows. I think I may have found a solution, which I'll get to in a moment.

Now, opening up a barrel channel to a consistent (larger) diameter is pretty easy... get yourself a dowel rod or piece of iron pipe that's about the diameter that you want, wrap it in sandpaper, and give it hell. Using epoxy (i.e., JB Weld) to "cast" a barrel channel is relatively easy, too... hog out the stock (remember the Dremel I mentioned earlier?), build a couple of modeling clay "dams" in the stock, wrap the barrel in a couple layers of painters tape, coat the tape in shoe wax/release compound, and bolt the barreled action into the stock. Pop it loose about 24 hours later, do a little cleanup in regard to the clay, do a little hand sanding on the JB Weld, and break out the spray paint. Kind of time/labor intensive, but it doesn't take any special tools or skills.

Anyhow, on to my latest brain fart... in order to make room for a Proof CF heavy Sendero barrel in a Boyd's stock inlet for a factory sporter barrel, I've taken a piece of iron pipe, and a roll of 2" wide painters tape, and "duplicated" the profile of the barrel by wrapping the tape around the barrel. Obviously, the profile of my iron pipe isn't as smooth as the barrel, but it is instead "stepped" in 2" wide increments... each with the same diameter of the as the barrel measured in 2" increments. The theory is that once you wrap sandpaper around it, the sandpaper will smooth out the steps/transitions in diameter. Anyhoo, figure out where along the length of the barrel channel the barrel (as installed) begins to narrow, back up 2" (the width of the painters tape), and put a piece of painters tape on the stock to mark the forward-most location along the stock that your iron pipe should travel. Wrap sandpaper around the taped up pipe, drop it in the barrel channel with the widest part of the whole assembly towards the rear of the stock (and behind the mark that you made a moment ago), and draw it forward until the (back) end of the iron pipe is at your stop mark. Repeat. Repeat. Repeat. Repea... ah, you get the idea.

Reading this, it seems really confusing, but it's really a pretty basic idea... you're basically creating a mandrel that has a similar profile to your barrel, wrapping it in sandpaper, and using it to remove material from the barrel channel in the shape of the barrel. At this point I have made my mandrel, and will work this weekend on using it to open up the barrel channel; if it works like I'm hoping it will, I'll take some pictures and post them here as an explanatory aid.
 
Very short stroke on the mandrel,,,,I'd use a straight dowel (an inletting cutter would be better) to cut to the smallest diameter first before going to the tapered, longer strokes= more material removal.

Consider center drilling/ threading a short stub of round rod ( 1/4"-1/2" ) into each end, chuck it into a VS drill and spin it. Light finger pressure on the other end to hold it down and keep it centered as best you can.

Never done it, but I'd give it try...

'Course, a friend with a mill would be a lot easier :)
 
Very short stroke on the mandrel,,,,I'd use a straight dowel (an inletting cutter would be better) to cut to the smallest diameter first before going to the tapered, longer strokes= more material removal.

Good point about the length of the stroke (yeah, I know... the comedy writes its self), and in fact, that is how I started (with the "bare" iron pipe with only a piece of 40-grit sandpaper wrapped around it). I think that my overall approach here was effective... the problem is that it's difficult to know for sure because while I have the barrel that I'm using, it is not yet installed in the action.

Doing some guesstimating using the (factory) barrelled action and my aftermarket barrel, it looks like the shape of the barrel inlet in the stock is pretty good, but is perhaps not yet deep enough for the clearance that I want (by my rough calculations, I have about .010 clearance at the bottom of the barrel channel at the fore end; I am shooting for closer to .040). I am going to wait until I get the aftermarket barrel installed in the action to do my final fitting, though.

My concern about using the power drill method (which certainly HAD crossed my mind) was that when I have done that sort of thing in the past, I have inevitably ended up with a beautifully shaped, visibly off-center channel. As for the mill, I have access to one, but neither the fixtures nor the knowledge to use it properly... I should probably do something with that opportunity, but it occurs to me that a $200 stock probably isn't the best place to learn (not that a $200 stock is all that expensive, but I'd sure hate to make a stupid mistake and ruin it).