New JB 5200 psi thicker. Post experiences with it or other stuff for bedding.

So I have bedded a number of rifles. Used Devcon, JB weld. Have a Marine-Tex kit waiting for next job since it was advertised as thicker, easier to control.

I have noted that original JB is indeed a bit runny sometimes. One video on youtube suggests that you need to mix it up and give it hour or so and it will thicken a touch.

I purchased a tube of the "new improved" 5200 psi version. Its still grey stuff, relatively slow to set up. I wanted the "runny" consistency of the JB weld on purpose this time around, as I wanted to flow some epoxy into a void behind the bottom metal on a stock.

Well, I was kind of disappointed today -- the new stuff is MUCH thicker, in my opinion, than the old stuff.

Now -- this is a GOOD thing if you were previously troubled by the runny nature of JB weld.

I figured this is an important enough observation to justify a post.

Feel free to chime in with other bedding choices that you have experienced, positive or negative.

Too many threads on this to start another of the same "what's your preferred epoxy", but I'll say that my important metrics are #1 shrinkage and #2 hardness. I rank compressive strength lower because I don't see how the recoil lug can generate forces that even approach those limits.

In my experience, Marine Tex is excellent for bedding rifles. I use JB Weld to bed ring & bases on scopes.
When assembling short range BR rifles, I use Marlene Tex to bed and glue them together with JB Weld
I know thickness of glue can vary when mixed

Much like how hitting something with a hammer produces a much higher force than merely pushing on whatever with the same hammer, the motion of the barreled action relative to the stock can't be looked at like it is just that push and expect to arrive at a solution for the maximum force developed. The Engineering term for the hammer's hit is "Impulse" and it is the Impulse generated by the barreled action in recoil that is the true force being applied to the bedding by the recoil lug. I would hope that the lug doesn't much of a running start at the bedding, so the Impulse shouldn't be many orders of magnitude larger like it can be when swinging a sledge.

Only a few of the bedding compounds commonly in use supply their shrinkage values. Makes it difficult to perform a fact-based evaluation.

ntsqd said:

Much like how hitting something with a hammer produces a much higher force than merely pushing on whatever with the same hammer, the motion of the barreled action relative to the stock can't be looked at like it is just that push and expect to arrive at a solution for the maximum force developed. The Engineering term for the hammer's hit is "Impulse" and it is the Impulse generated by the barreled action in recoil that is the true force being applied to the bedding by the recoil lug. I would hope that the lug doesn't much of a running start at the bedding, so the Impulse shouldn't be many orders of magnitude larger like it can be when swinging a sledge.

Only a few of the bedding compounds commonly in use supply their shrinkage values. Makes it difficult to perform a fact-based evaluation.

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True- which is why I linked the common one above which I happened to find- but not on JB's site.
I did, however email them about providing their product data sheets with that and was provided a contact email to obtain the information. What- takes up too much bandwidth to put it on their website? Ridiculous...

Frankly, IMO this is as much "overthought" as anything else in this discipline. Most everyone, including the pros, use either Devcon 10110 or the gray Marine-Tex. Not saying everyone...but safe I think to say most. Regular JB Weld probably third. Why get in the weeds when there's already a consensus.

I use the Aluminum Dev-Con, partly because that is what I was told to use way back in the 80's when I was just starting to learn about this sort of thing, and partly because since then I researched it and found out that it is slightly stronger (!) than the steel putty and I don't think the real world difference in shrinkage is worth worrying about.

tobnpr said:

Frankly, IMO this is as much "overthought" as anything else in this discipline. Most everyone, including the pros, use either Devcon 10110 or the gray Marine-Tex. Not saying everyone...but safe I think to say most. Regular JB Weld probably third. Why get in the weeds when there's already a consensus.

Click to expand...

I'm with you on the top two. I really like 10110 but they got super proud of it… I've been using ProBed2000 and while a little thinner, good alternative.

Thanks for the info. I use silica fume to thicken mixes. You could use that on JB to get your own consistency. I only use JB for thin layer applications where the epoxy will be permanently sandwiched, such as bases.