Home Forums Hunting & Shooting Gunsmithing Polyurethane Foam

Hi,

I have a Cavalry Mfg AR-15 A1 stock that I would like to fill with polyurethane foam after perhaps epoxying a recoil reducer in the stock (for a 450 Bushmaster).

Which weight polyurethane foam do you generally use? I know it's sold in 2lb, 4lb, 8lb etc.

Thanks,

Dan

You need a two part chemically activated foam. The spray cans you buy activate with air and will make a mess inside a stock. Been there. The big trick is getting the right amount mixed and poured in. If you do too much, you run the chance of the foam expanding and cracking the stock. ALMOST been there with that one.

Twp part foam isn't hard to find and not expensive.

That's the exact stuff I was referring to. My question is what density... 2lb,4lb,8lb?

Dan

I don't recall which I used. I was just after filling to hollow stock, not so much as a structural aspect. Go with the 4 pound if you don't have a weight restriction.

Since it is not structural 2LB should be good. If adding a reducer I slice the foam even with the but stock and then drill for the reducer and a tube to put it in.

Disclaimer I have not put in a reducer this way before but have added weights in the same fashion to balance a rifle.
If weight is not an issue go with the densest foam and it may have enough strength by itself that you won't need to glue in a tube for the reducer. Besides if your trying to reduce recoil the added weight will be beneficial.