Have a CZ-550 SM, looking to bed into a pillared McMillan stock, that has been cut for this barrel/action (#8 Lilja contour), chambered for the 300 RUM Improved.

I'm leaning toward Agra-glass (with or without flocking), but others have suggested using Devcon Steel putty instead.
Your opinion on the best choice?

With the pounding the recoil area will receive, I would lean toward a steel-filled epoxy. Practically incompressible.

I have used the steel filled Devcon epoxies and they are great. Once they harden they are glass hard and you have to grind them out.

I also use Acuraglass gel. Works fine.

I have not seen material data on either, it is my opinion that the Devcon with the steel fiber reinforcement would be stronger.

But, given a sufficient thickness, I don’t see why either would not work well.

To me, it is more important to have a thick bedding layer, one that relies on the strength of the bedding compound, ignoring any structural or mechanical strength of wood. These bedding compounds are stronger than wood, just the exact amount, I have never looked up. Maybe be several times stronger.

I use Johnson paste wax as a release agent on non critical bedding surfaces, use spray on mold release for the areas I want a tight fit.

quote:

Originally posted by SlamFire:
To me, it is more important to have a thick bedding layer, one that relies on the strength of the bedding compound, ignoring any structural or mechanical strength of wood. These bedding compounds are stronger than wood, just the exact amount, I have never looked up. Maybe be several times stronger.

Ummm fiberglass stock (not wood) and a skim coat bedding layer, not a thick coat

devcon titanium putty is the choice of the tacticool community around here. although being god awful expensive it is easy to work with, gets harder than woodpecker lips and doesn't rust.

Brownells has a steel bedding compound. I have used it with no customer complaints on 300 Rem Mag, 300 Wby Mag, 416 Rem Mag, 375 H&H rifles. Reasonably priced and works like AcraGlas gel.

Since the stock is already pillared, then the hardness of the compound would seem to be largely immaterial since the pillars take all the compression strain anyway.

Or am I missing something here?
Regards, Joe

quote:

Originally posted by J.D.Steele:
Since the stock is already pillared, then the hardness of the compound would seem to be largely immaterial since the pillars take all the compression strain anyway.

Or am I missing something here?
Regards, Joe

What about the recoil bearing surfaces (i.e. recoil lug)?

I like Devcon 10110 Steel putty with Kiwi neutral as a release agent (buffed thin). If anything I like the consistency of Devcon, kinda like smooth peanut butter.

If i'm out of devcon i can't tell any difference using j-b weld.

I like Bisonite, Devcon, and just about any fibreglass boat hull repair kit, in that order.

Speaking of epoxies, for a close fit two layers work better than one layer. For an exaggerated example, here's why:



Lets say we want to fill a space 11" deep, and our epoxy shrinks 10% as it "sets". Okay, we pour in 11" of epoxy in one layer and let it set. How thick is it when all hardened up? Just 9.9 inches, leaving a 1.1" gap.

How about if we use two layers? Okay, the first we will pour in 11" of epoxy. when it has set, it will be 9.90" thick. As we need to fill 11" of space, we now pour in 1.10" more and let IT set. it shrinks .11", adding .99" thickness to the 9.90 inches we already had, giving us a total thickness of 10.89" instead of the 9.90" we got when we only used one thick layer.

The same happens with rifle bedding. ALL expoxies normally sold for use in rifle bedding shrink as they set. (They don't shrink 10%, that was just for the exaggerated example, to make the point.) So the best way to get a full, close, fit, is to use more than one layer, letting each layer fully set before adding the next one.


Note...this info was correct as of 5 years ago when I last bedded as rifle. It is possible that a new bedding prtoduct has been developed which may even expand when setting, as various insulating foams have long done. But if that has happened, I have not heard of it or seen it advertised anywhere.

The object of the pillars is to provide a solid fit for the action screws , so they can be properly torqued ! There can still be movement due to a loose fitting recoil lug , especially on a big boomer !