Home Forums Hunting & Shooting Gunsmithing Back-filling a McMillan barrel channel...

What's the best way to do this? I've got a rifle that the barrel channel gap is a little wider than I like. What's the best way to back-fill that? I'd assume epoxy, but is there a good way to maintain a nice, consistent gap?

Thanks,

Dan

Tape the barrel to the thickness of gap that you want. Piece of cake.

I filled mine with phenolic microballons mixed with a little epoxy. I don't remember the ratio, but the cured material is light, and easy to sand. You can get microballons from most fiberglass suppiers:

http://www.fiberglasssupply.com/Product_Catalog/Fillers/fillers.html

RAN

I've used Cab-O-Sil for years as a thickener... I noticed fiberglasssupply.com sells it.

West system with 407 low density fairing filler.. Other options are out there, but I'm pretty comfortable and confident with West System..

Same thing as epoxy with microballoons which somebody said they found at a hobby shop. Add to (a thin) resin until it's like peanut butter. Nice and light but not too strong. "Syntactic foam" is the ten dollar word for it. West System is good. Lots of good info on their web site though it's boat oriented. West System

I have used both micro balloons and West 407 filler. I probably prefer the 407 filler, but not by a big margin. I have also used routing out of the forend material and inserting aluminum arrow shafts to keep weight down and stiffness high.

Thanks for all the help guys. One quick question though...are you guys mixing the 407 with Steel Bed or something?

Use any medium or thick set epoxy. I get some of mine from Woodcraft, I believe it's called "system 3"

If you're unsure, get some acraglass gel, and micro-balloons. Mix it up, I tape the barrel with 2-3 layers of Blue painter's tape, coat with release agent and then put it in the stock as you would normally.

Once cured, peel the tape, wipe down, oil and throw it back together.

Just watch your tolerances. Barrels expand/shrink so don't bed it at 40* and hunt with it at 95* without checking for clearance.

clark--
I just have the big kit of Acraglas Gel that I use for this kind of task. My guess is that Steel Bed would add back weight the filler is attempting to reduce. Remember, this is more cosmetic than structural. If you want to use steel bed to bed the action, that is another matter. (I tend to use Marinetex for that.)

If it is a major gap I use the micro balloon filler with lots of tape on the barrel. Then I re-bed with three layers of tape and epoxy with powdered graphite and no micro balloons. This makes a harder shell that won't chip as easily. The graphite powder is mostly so scratches don't show as much but it may add a little strength.

Thickness of the tape is approximately .005, 4 "strips" will give you .020 clearance and usually works well on quality stocks (McMillion and such), floppier go .030.

good thread.




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