What is the opinion on changing a Navy Arms Baby Rolling Block in 357 Magnum to 357 Maximum? I'm thinking it might not be beefy enough for the increased pressure. I believe there are people that have did this but haven't spoken with any of them.

Steve E......

I don't think it would be a good idea. I don't think that that action can handle the Max without stretching.
If you can find him, there is a man by the name of Perry Mittlestat(sp?) that lives in western Colorado. He used to do a lot of work, very, very nice work, with rolling blocks. He could probably answer your question.

Pressures are about the same with both, ~40K psi or so; case heads are exactly the same area so the breech face thrust should be the same. The only 2 limiting factors that I can see would be the increased recoil from increased velocity & charge weight in the light rifle and (remote possibility) a VERY slightly increased breech face thrust, again from the increased velocity rather than any pressure.

I'd say it was OK but I don't own one.
Regards, Joe

I know that these guns were (are ?) made in .30-30 Winchester which operates at similar pressures (38,000 CUP or 42,000 psi SAAMI specification), has a larger case head, and shoots a similar weight bullet, but at a higher velocity. I would think that if it works for the .30-30, it should work for the .357 Maximum.

Same presure, no problem. These were well made and fairly strong.

bolt thrust is psi*surface area.. it is actually INTERNAL diamter, but when comparing 2 cases that very nothing but length, it doesn't mean anything

Bolt thrust has nothing to do with velocity or (as some have said) bore diameter. A 7mmSTW, (pi(.532/2)^2) *63000 at 3300fps has EXACLY the same bolt thrust as a 458 lott, 500gr at 2300, (pi(.532/2)^2) *63000

then again, pressure has nothing to do with velocity, either.. and you KNOW that, its just not obvious ... if the 357 max goes faster than the mag, at EXACTLY the same pressure, then how can max or peak pressure have anything to do wiht anything? Its the work, or area under the pressure/time/volume curve that drives velocity.

Thanks Guys for the advice.

Steve E.........