MR 50 powder, anyone have info on it?

[thebrute]

I recently acquired some MR 50 powder. I can't find any information on it at all. The only reference to it I have been able to find is in an OLD Lyman reloading manual. I can't give you the date of the manual because the cover page with the publishing data is missing. The only two loads mentioned are on page 113: a 16 grain charge of MR 50 in a .30-06 with a Lyman 311241 bullet; and, page 120: a 16 grain charge in a 7.7 Jap with a 311413 bullet.

I have about 10#'s of the stuff and would like to use it up for practice and plinking loads for a .30-30, 7mm-08, and if suitable for a .222 or .223.

I'm making an assumption that this may be a powder manufactured prior to the Dupont IMR powders, the MR probably stands for Military Rifle. There is no reference to MR 50 powder to be found anywhere on the internet.

I'd appreciate any information you could provide.

[Ricochet]

I'm making an assumption that this may be a powder manufactured prior to the Dupont IMR powders, the MR probably stands for Military Rifle.
That part's correct. The "Improved" part came when they started coating the tubules with deterrent to make them progressive burning. The MR powders were nonprogressive. Don't know where you'd find loading data in your cartridges. Best you can do is to use the data you have to estimate what it's closest to in modern terms, start low and work up your own loads. The powder's burning rate may have changed, probably faster, as it's aged.

[BerdanIII]

I looked in Sharpe, Ness, Ackley, Whelen, all of the Handloader's Digests and all of the Lyman manuals I have and only found the two loads you mention. Check Lyman's most recent cast boolit manual, maybe you can match up MR50 with a modern powder in terms of charge weight/bullet.

[thebrute]

Thanks so much for your effort , fellows. Ricochet, I think I'll start light on a few of the .30-30 loads and see if there are any signs of pressure. I'll load a 115 grain 3118 Lyman bullet sized to .308. The fact that the powder may burn faster concerns me though. If I get any signs of inconsistency the rest of the powder will be on my next brush pile as an igniter!

[Ricochet]

Nitrocellulose over a long time loses a tiny bit of its nitration, and loses a little energy with it. But in that process the molecular chains break and end up as shorter fragments, making the powder grains more brittle. It tends to shatter when the primer fires, and the smaller fragments of powder grains have more total surface area. That's why old powder often burns faster and raises pressures. It's often the limiting factor determining when stored military ammunition is surplused or condemned.