Filling a McMillan barrel channel.

[Curious]

Guys,

Ive got a used McMillan FClass stock that has had the barrel channel opened up to 1.5" along its entire length, I guess previously it had a big barrel in there.

I would like to fill the barrel channel and start again to fit a typical FClass profile. 1.25" to .9" at the muzzle.

Im thinking about bedding the barrel back into the channel using something like chopped fibreglass car body filler or even the smoother surface filler - has anyone used this?

I could put some heat shrink over the barrel and use release agent to give me a close fit or alternatively I could just slide the barrel forward in the stock when setting it into the filler and that will give me the clearance. How much clearance would be enough without being too much?

Any suggestions on my method and the materials to use?

 

[jepp2]

I could put some heat shrink over the barrel and use release agent to give me a close fit or alternatively I could just slide the barrel forward in the stock when setting it into the filler and that will give me the clearance. How much clearance would be enough without being too much?

To get the clearance I would put a few layers of Brownells 2" wide bedding masking tape
https://www.brownells.com/gunsmith-tools-supplies/stock-work-finishing/stock-bedding-accessories/bedding-tape/bedding-masking-tape-prod1229.aspx
coated with Kiwi neutral shoe polish.

With typical bedding compounds, sliding the barrel back and forth isn't going to work. The compound will adhere to the barrel/shrink wrap/tape. I will let others comment on what to use. I would tend to use Devcon, but that is a lot of Devcon.

 

[Alex Wheeler]

If I ever need to do non structural fill work I use west system epoxy and micro balloons mixed to a mayonnaise consistency. Some milled glass or finely chopped glass will add some strength.

 

[Dusty Stevens]

Id bed it with thick bedding tape and jb weld. Thats how mcmillan does it when they bed barrels. Works good for me too. But another alternative is leave it like it is- space around the barrel is a good thing especially in f-class, and you never know if youll go back to a bigger barrel.
This is what i use:
https://www.3m.com/3M/en_US/company...318600&preselect=3294629354+3294857497&rt=rud

 

[Bully]

JB or Devcon and wrap the barrel with 1 or 2 pieces of "Pipe Wrap" and some release agent. That's what I would do. I have not done it yet but it's in the plans for one of my stocks.

Good luck.

 

[Mozella]

If I ever need to do non structural fill work I use west system epoxy and micro balloons mixed to a mayonnaise consistency. Some milled glass or finely chopped glass will add some strength.

I haven't checked in a while, but West used to pre mix glass bubbles with some milled glass and some colloidal silica. This mixture (I forget what they call it) might be cheaper to purchase than buying all three components to make filler. The glass bubbles are for bulk (weight reduction), the milled glass is for strength, and the colloidal silica is to adjust the viscosity. Of course, if you have the materials on hand, you can make your own custom mixture. Mix the dry stuff first, then mix the resin with the hardener, and then combine the epoxy with the filler.

I would lay a strip of .010" pipe wrap down the barrel for clearance and wax it well. I would scratch sand the stock with some 36 grit paper and mask every place I didn't want to contaminate with epoxy. Then paint some unfilled epoxy onto the stock to improve the bond between the stock and filler. Then I would mix the filler and epoxy thick enough not to run, trowel in the filler, and then fit the barrel and action into position. Scrape off the excess, let it cure and then pop the barrel out. Sand and paint.

 

[yukonal]

I've filled/bedded barrel channels with 2 layers of gorilla tape on the length of the barrel, and 10110 in the channel.

 

[Curious]

Thanks for your thoughts so far guys, I should have said earlier that Im also looking for a lightweight solution so Devcon or pure resin isn't really an option. I thought car body fuller with glass in was an option but I will also look into the micro balloons to add to some resin.

Im usually quite happy with plenty of barrels channel clearance but this time I would like a nice fit with just enough clearance and minimum show gap down the barrel, maybe in the region of 0.040" each side?

Please keep your thoughts coming.

 

[Mozella]

Thanks for your thoughts so far guys, I should have said earlier that Im also looking for a lightweight solution so Devcon or pure resin isn't really an option. I thought car body fuller with glass in was an option but I will also look into the micro balloons to add to some resin.

Im usually quite happy with plenty of barrels channel clearance but this time I would like a nice fit with just enough clearance and minimum show gap down the barrel, maybe in the region of 0.040" each side?

Please keep your thoughts coming.

Car body filler is a poor choice. It's nearly always polyester based and therefor isn't very strong, it isn't very waterproof, and it shrinks a lot. It's OK on car bodies if applied in very thin skim coats but anyone familiar with working on cars will laugh at those who think using a Bondo type material for filling thick sections is a good idea.

Stick (no pun intended) with a good, two part, slow cure, epoxy product.

 

[BLCKWLF]

Id bed it with thick bedding tape and jb weld. Thats how mcmillan does it when they bed barrels. Works good for me too. But another alternative is leave it like it is- space around the barrel is a good thing especially in f-class, and you never know if youll go back to a bigger barrel.
This is what i use:
https://www.3m.com/3M/en_US/company...318600&preselect=3294629354+3294857497&rt=rud

Marine Tex. That's what we used when we bedded rifles. When we fill a barrel channel like that, and re-inlet it, we fill it with the same material we filled the stock to begin with, a proprietary fiberglass epoxy composite.

Some use epoxy mixed with fiberglass, or just a ton of JB weld or Marine Tex/devcon/etc.

 

[BLCKWLF]

If I ever need to do non structural fill work I use west system epoxy and micro balloons mixed to a mayonnaise consistency. Some milled glass or finely chopped glass will add some strength.

That's how its done.

 

[alinwa]

Ian Robertson posted some seriously in-depth stuff over on BRC a while back. Search his name and you may well find it. He actually posted full formulaic rundown of his system which is world-class. He named the names, the suppliers, the flocs etc...

I went out and bought a bag of Aero-Sil https://www.amazon.com/dp/B0015MWNWK/?tag=accuratescom-20 altho I'd used a few pounds of Cab-o-Sil http://www.jondon.com/cabosil-m5-ep...MIpcfI6PbX3QIVCgNpCh2X5wlEEAQYASABEgJhEvD_BwE in the past and by mixing this stuff with Acra-Glas you can make ANYTHING you want from peanut butter to circus peanuts to glass-hard bedding compound.

I love the stuff.

BTW, the 22lb bag is freaky-large literally the size of a Polan' China feeder pig.........

 

[alinwa]

By the way, this fumed silica will scare the krapp out of you when you open it. I opened a gallon just of it off the shelf at a TAP Plastics supplier and it wafted out and into my nose and eyes and all I could thing of was "Black Lung!!! Pneumonoultramicroscopicsilicovolcanoconiosis!!! "I'm Gonna' DIE Now!!!""

It's the stuff they make "wind puffers" and "deer smoke" out of.... you CAN breathe it, it just might make your boobs bigger or something, I dunno.....

The petite-Asian-woman-sized bag I have now is a treat, I tape it shut when not in use....... open it slooowwlllyyyyyy in a still room and run these half-gallon plastic supplement jugs I get from my Mom down into it and put the lids on IN THE BAG.....

 

[Keith Kilby]

I've repurposed several stocks that had oversize barrel channels. I've been using free bicycle inner tubes from a local bike shop. A bit of lube on barrel and they slide right on. Leaves a perfect, equal gap down both sides of barrel. I use marine tex.

 

[alinwa]

I've repurposed several stocks that had oversize barrel channels. I've been using free bicycle inner tubes from a local bike shop. A bit of lube on barrel and they slide right on. Leaves a perfect, equal gap down both sides of barrel. I use marine tex.

THAT is friggin' BEAYOOOTIFULL!!!

 

[alinwa]

I went to thee local bike shop today and walked out with TUBAGE!!!!!

Thank You Man

(altho dealing with them asspeddlers is a 'YUGE price to pay..... but I did manage to come away with no permanent harm done to either party(s) LOL!)

 

[Keith Kilby]

Al
I can't speak to any other release agents other than what I've been using...the aerosol from Brownells. The inner tube, marine tex and spray release all play well together. The inner tube also allows you to "cut off" squeeze out without scratching the barrel...even though I use a beveled popsicle stick....After it gets just past chewing gum consistency you can easily remove the excess without pulling any bedding out. I keep stick wiped off and lubed with saliva. Works like a charm for me. My local bike shop asked how many take off/leaky tubes I wanted....it looked like they had never thrown one away!

 

[gunsandgunsmithing]

Al
I can't speak to any other release agents other than what I've been using...the aerosol from Brownells. The inner tube, marine tex and spray release all play well together. The inner tube also allows you to "cut off" squeeze out without scratching the barrel...even though I use a beveled popsicle stick....After it gets just past chewing gum consistency you can easily remove the excess without pulling any bedding out. I keep stick wiped off and lubed with saliva. Works like a charm for me. My local bike shop asked how many take off/leaky tubes I wanted....it looked like they had never thrown one away!

They are a great idea! In the past, I've used heat shrink tubing. It works well too but isn't really cheap nor handy around here. I like the fiberglass body filler for the barrel channel, personally. It's easy to work with, sets up strong and fast, and sands much better than epoxy. It also feathers out pretty well...again, better than epoxy. JMHO and 2 cents worth. As with so many things, YMMV.

 

[Keith Kilby]

I've only done one that was so oversized I probably needed an additional filler. Several good ideas here for filler material for filling really big gaps. On that stock I made a modeling clay rib down the center of barrel channel up to just short of fore arm tip. Torqued barreled action in to form the clay, then just bedded the sides and end. Cleaned the clay out after. Finished job wasn't the prettiest in the bottom of barrel channel but it saved a bunch of bedding compound.