I'm curious if there is a formula figuring what's safe when going to a larger and higher pressure round?
I'm considering cutting my H&R 45-70 to 458 Lott. If I like it I will probably buy and cut a Ruger #1 as well. I understand people also cut the Ruger to 460 Weatherby, but how do you figure what's safe with fat shells like that? Could my existing H&R handle a 460 Wheatherby? It's chamber OD is a solid 1.125" for the first 3-1/2", then tapers to .970 at around 4-1/8", then to .808 at the muzzle.
This H&R rifle will basically just be an experiment/toy, no big loss if it don't like the end result.

Thanks for any input you have.

P.S. Yes I called H&R on the subject, they gave the standard disclaimer: "Leave it alone and only shoot factory ammo".

I would immediately discard the idea of reaming the H&R. When they first came out they were classified (by Handloaders Digest on information from H&R) as a Class I (weak) action along with the Trapdoors. This was due not to materials but action design.

The Ruger is a Class 3 (strongest). But I load my No.1 right up there at red-line and I don't care for more recoil.

I've seen the No.1 Africans at shows for $500-550. They are a little heavier than the .45-70. That probably means Ruger thinks that extra metal, whereever it is , to be necessary.

I second that on the reletive weakness of the H&R rifle. Best to leave it in the original caliber. Go for a Ruger NO. 1. Plenty of strength for anything you want to use it for. I have a .458Win. altered to .458Lott. Never a problem except for the recoil. Installed a Pachmayr Decelerator pad to tame the recoil.

chevota---

The last H&R I saw had a cast iron reciever. I wouldn't shoot one in the calibers offered, much less something hotter.

The extra metal in the Ruger No. 1 .458 Win. is not due to pressure. It is to keep you from losing your shoulder when you fire it. The hot-loaded No. 1 .45/70's are murder!!

Thanks for the replies everyone. I'm really surprised about the notes on the H&R/NEF being weak. I know it is not an expensive gun, but I owed that to minimal machine work and parts of a singleshot, also a very basic finish and a joke of a stock. But I never thought it to be weak, it seems to be solid and very thick compared to my other guns.

I also wanted to figure safe pressure for my Ruger mini-30, and a very thin walled 12Ga barrel I have. So if anyone comes along with a formula or "rule of thumb" for figuring what's safe for chamber thickness, please let me know.
Thanks, Corey (chevota@hotmail.com)

chevota---

I think you're misunderstanding what is meant by “strength”. The thickness of the barrel or chamber makes little difference as to what’s safe.

It’s true that some barrels fail….there were dramatic pictures of a wrecked M1-A not long ago…..but that’s due to *bad* barrels, not excess pressure.

It is the action that protects your tender parts. How the action supports the cartridge case is first, how the action deflects, slows, diverts, and channels the blast of hot gas and melted brass when the case lets go determines if you can SEE the damage done when the smoke clears. On 99% of blow-ups the barrel is not damaged.

The H&R is basically a cheap shotgun with a rifle barrel on it. They come apart in spectacular fashion when the action breaks at the corner of the standing breech. I’ve seen two 30-30s that failed….DON’T hotrod anything in the H&R/NEF line.

The Ruger Number One is one of the world’s safest rifles. At high pressures they stop extracting. That’s the signal to back (way) off. When cases fail it blows out the extractor notch and melts the end of the extractor and blows the debris out the bottom.

*Some* action are suitable for *some* calibers. Some aren't.