Home Forums Hunting & Shooting Gunsmithing Glass bedding question

Got a question for you gurus of glass bedding. I have glass-bedded a few guns before but have encountered a new issue with a Kimber 84M Hunter I recently acquired. I guess in an effort to save weight, the stock channel and action area have honeycomb holes. See linked picture. I assume I need to fill these up in the chamber and action area before I can glass bed.

What should I use to fill them up? The same bedding compound/epoxy? e.g., Acraglass, etc.?

Also, getting the compound down in there seems like a messy task. I was thinking I could use a large syringe or similar to squirt epoxy material down in the holes. Mainly I am just looking for the cleanest/most efficient way to do this.

Any thoughts/ideas/suggestions are appreciated.



Thanks,
Kyle

That looks injection molded.

If so, glass doesn't usually stick that well to injection molded stocks.

It's pillar bedded, why do you want to glass bed it?

Filling the honey combs with glass will take a lot of material and will increase the weight a good bit.

How stiff if the forearm and is it free floated?

DF

Hello Dirtfarmer, thanks for your response.

Yeah, I have the same concern as to whether the glass would stick. I'm not sure if the stock is injection molded though. It doesn't have as cheap a feel as Remington tupperware stocks or similar, and Kimber's website lists the stock as being "composite," but who knows, it could be injection molded.

I have had the rifle a few months and been trying to develop a consistent, accurate load. I seem to keep having the issue of getting two shots near or on top of each other, with a flier shot 2-3 inches away. I tried one brand of factory ammo and didn't fare much better.

I've checked all the action, bases, ring, scope screws, and I don't think it the scope itself (Leupold). The forearm is fairly stiff, but does flex toward the end. The barrel is floated up to the chamber area. I can't tell how much of the chamber area is contacting the stock and I'm not confident it's got solid contact. I'm just wondering if I'm getting some random stock/barrel contact that would benefit from bedding the chamber/lug area.

Perhaps the best course of action is to be patient and continue trying load development until I'm certain it's a bedding issue.

Bedding never made a rifle shoot worse and why waste components and time?

I fill those with epoxy fluffed with microballoons. Little weight, much stiffness... rough up the surfaces, undercut them and drill holes through the web repeatedly.

I've done as Sitka describes with success. It definitely needs roughening up to bond, and the drilled holes help.

I'd bed the recoil lug area and maybe a little bit of barrel in front of and call it good.

I would most DEFINITELY try another scope before making any alteration to the rifle. You may want to bed it anyway once it's all said and done, but if I was you I'd sure want to be sure I know how the rifle shoots before bedding. If it IS a bad scope, then you'll never know how it shot in original condition if you bed it first and it does turn out to be a bad scope. I like Leupold, but they can break just like all the rest.

If it ain't broke, don't fix it. Before bedding I'd check to see if it's floated. If not, do that and go shoot. Next, install a bore sighter and while looking through the scope try every imaginable twist, torque, push, pull on the stock components, and see if anything moves. Last, leave the bore sighter installed, check it's position, and loosen/tighten one's action screws checking again for any signs for movement or stress. If anything moves then the stock assembly is stressing the barrel/action somewhere. If that's the case, then I would take on bedding.

How about the higher density spray urethane foam? That stuff sticks to anything. Never tried it for something like this but I think I would. Have used a microbaloon/epoxy filler for lots of things and that would work.

I agree with Sitka, but I would do the barrel channel separately from the receiver. Why? Because you want to mix in as many micro-spheres or as much light-weight filler as you can with your liquid (not paste) epoxy and still be able to pour and fill the holes. I've done this successfully using polyester/fiberglass resin making sure that the hardener was thoroughly mixed before adding filler - if you also are adding tint color, mix in last. That compound when hard will provide enough stiffness with much less weight which is what you need more than strength.

Bed the receiver as you normally do. If the stock is a plastic-type polymer, you might be better off using a 2-part epoxy that is made for plastics. JB Weld has a clear epoxy called CLEAR WELD that will hold permanently with most plastics with a strength of 4400psi - it has about the same hardness - maybe slightly less- as Acra-Glas gel. Since you've already got aluminum pillars, compressibility may not be a concern, but if so you can always add a little powdered SS or aluminum filler for more strength.

A WORD OF CAUTION: make sure that you read the SET-UP time - I think the JB Weld CLEAR WELD will set up in 5 minutes. Anyway, there are others out there that work with plastics, just don't ignore set up time. However, the same is true when using FG resin, so if you have not used either before, you might want to practice with a small batch first.

Before doing that, you have to degrease/clean the stock. Without knowing exactly what type of polymer the Kimber stock is made of, I would suggest that you test clean some internal area first with lacquer thinner - it is just about as quick to evaporate as acetone, just not quite as reactive with plastics. If you get a reaction with the lacquer thinner, then I would thoroughly clean the stock with a good detergent and hot water, especially the internal areas like those holes in the forearm. If you have any kind of oils or residual mold release from when the stock was made, your epoxy bedding and FG resin will not adhere well.

I'm sure I've probably missed something, but I've done so much of this, I don't really think much about what and how - I just do it. Anyway, I'm sure someone else will think of what ever I missed.

Additional: I have two types of fillers - one is "glass micro-spheres" by System Three Resins, Inc. Ostensibly, it is for thickening resins to create a paste from liquids. I've used it for filling non-critical areas like your forearm before, but usually with epoxy-based composite or fiber-glass/kevlar shell-type stocks. I would test one hole with a small batch, let it cure for 24+hours, then screw around with it and see how well it sticks, and how solid, etc. The other filler I use is high-density but still lighter-weight versus solid epoxy - it IS made for high-strength application (boat hulls) where thickening is desired without loss of adhesion. It's called 404 High-Density Adhesive Filler made by West System (West Marine). I don't have much of it left, but I have lots of the glass micro-sphere filler. PM me if you can't find any where you are. Good luck.

Two thoughts... ALWAYS use slow-curing epoxy... Never a concern about pot life.

Why complicate things and make it a two lift job? Just do it and get away from it!

I've bedded several injection molded stocks with never a problem. Like others said, rough it up good, drill holes in different direction to create a lock and clean it good. I also agree with S.D., do it in one shot and be done.

One thing noone mentioned, 2 shots touching and one out of the group is a classic sign that the load isn't where the rifle wants it. Many time cured by doing more than adjusting O.A.L. of the load, usually a few thou shorter.

Same as Sitka here. I have used Brownell's acruglass,not the jell and mix it with the microballons used in air soft rifles

The reason I suggested two jobs is that in the fore end, he needed rigidity - not strength - and if he filled it with nothing but epoxy it would be noticeably heavier. However, adding the microsphere filler makes it lighter but at the expense of strength and resistance to compressibility - which means that would be a poor choice to bed his receiver with.

Just so we are all on the same page...

Glass microspheres are microscopic spheres of glass manufactured for a wide variety of uses in research, medicine, consumer goods and various industries. Glass microspheres are usually between 1 and 1000 micrometers in diameter, although the sizes can range from 100 nanometers to 5 millimeters in diameter. Hollow glass microspheres, sometimes termed microballoons or glass bubbles, have diameters ranging from 10 to 300 micrometers. (0.000393701 to 0.011811 inch)

Hollow spheres are used as a lightweight filler in composite materials such as syntactic foam and lightweight concrete.[1] Microballoons give syntactic foam its light weight, low thermal conductivity, and a resistance to compressive stress that far exceeds that of other foams.wiki

And the ratio of microbaloons to resin changes the resulting properties dramatically.

Just because it has pillars, doesn't mean it doesn't need to be glass bedded. I'm surely hoping you know this. Personally, I'd glass bed the sob and make sure the barrel is freefloated enough that it will never make contact, regardless of where you put in in the bags, front rest, use a bi-pod or tight sling. That's just how I roll...

And that is how I did them for many years... Then I started stress-free, full-length bedding and have not looked back.

With slow-curing epoxy you have plenty of time to mix the epoxy and apply it to the critical bedding areas before fluffing the epoxy with microballoons and filling the foreend areas. If stiffness is desired I grind out all the lateral braces in the front and bed sections of broken fishing rods in the fluffed epoxy. It makes them stiff without making them heavy.

I took a second look at the OP's picture because it hit me it is honeycombed, rather than more typical fore end webbing. I would grind that all out and refill with rods and fluffed epoxy.