7.5x54mm MAS FNM Powder


Dave Rishar
April 4, 2013, 02:34 AM
Quite a few years ago, I bought a MAS 49/56. My dealer helpfully offered to sell me a good quantity of ammunition along with it. This was first generation FNM and as you might know, it did not cycle the rifle. (It also frosted the bore up pretty good, despite being advertised as non-corrosive. I don't know what happened there.) Both sat in the safe for over a decade after that.

Now I'm interested in shooting it again. The idea of pulling down the ammo and reassembling it properly never occurred to me before now, but that's what I'm doing. I understand that others have done the same. My question to them is, what does this powder compare to? I'm prepared to work up new loads from ground zero but I'd much prefer a bit of guidance or observation before beginning. I'm going to have a few pounds of this stuff by the time that I'm done pulling it all down, so I'd really hate to throw it all out.

It looks to be a ball powder with a graphite coating. Beyond that, I can't say anything yet. I know how much is in each case and I know that it's not enough, so I at least have a place to start at. I'd still appreciate any information that anyone has.

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Jesse Heywood
April 4, 2013, 02:48 AM
A previous discussion

April 5, 2013, 04:51 AM
Unless those FNM cases are Boxer primed, you might as well save your time and start fresh. Your 'frosted' bore indicates corrosive primers, so whatever you load that pulled-down brass with, it's still going to be corrosive. That powder is an unknown quantity, most people would say use it to fertilize the roses. You could salvage the bullets and powder and carefully work up new loads based on the charge that your FNM stuff is loaded with, using the new brass that is available from sources like Graf &Sons. I believe I saw loading information for this cartridge in a Speer or Hornaday manual. Military ballistics are supposed to be a 140gr bullet at 2600fps.

Also, MOST important, if you do load with new Boxer primed brass be sure to get CCI primers for 7.62 NATO, I think they are #80. The slam fires mentioned in the THR archive article are due primers too sensitive for the autoloader action. I believe Tula primers are also reported to be harder as well, might be suitable. You do NOT want the rifle to start firing on it's own, I had an SKS that exhibited that ugly habit, which I quickly disposed of.

April 5, 2013, 08:11 AM
If you have no experience in reworking surplus ammo, IMO, it's risky to work up loads using an unknown burn rate powder. If you want to increase the velocity and resulting pressure to function the action, using a known powder with listed loads is the way to go.
It's my understanding that surplus milspec 7.5x54 Mas ammo is loaded with corrosive berdan primers, and will require a thorough cleaning of the rifle after using, regardless of your choice of powder. It's a chore to reload berdan primed brass, if you can even find the correct size primers.
If you can locate some Prvi-Partizan boxer primed brass or ammo, then you wouldn't need to worry about corrosive berdan primed ammo. Sell the surplus and buy boxer primed stuff that you can reload.


hang fire
April 5, 2013, 08:24 AM
Why is this myth perpetuated that corrosive primers frost the bore?

There is no difference betwixt firing corrosive versus non-corrosive primers as to effect upon the bore.

It is the ignorant and stupid shooters not correctly cleaning the bore after shooting corrosive ammo which creates problems.

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