January 18th, 2010, 01:19 PM
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#4 |
| Grunt
Join Date: Mar 2008 Location: SW Oregon
Posts: 110
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I'd recomend using IMR 4895; 43.0 for 150 bullets and 41.5 for 165/168.
Borrowed from THR
Many loading manual have listing for service rifle. For example, the 7th edition Hornady manual has sections for servce rifle for 308, 30-06 and 223, IIRC.
The standard match round for the M1A and similar rifles is 168gn SMK over 41.5gn H4895 in LC cases.
Here's a bit on duplicating M80 that was passed on to me. You can buy WC846 pull down powder for about $100 for 8 pounds.
Mil spec for M59 Ball:
Bullet: 150.5 grain FMJ
Powder: 46 grains WC846 or 41 grains IMR 4475
Velocity = 2750 +/- 30 fps @ 78 ft.
Pressure = 50,000 psi max average.
Accuracy = Carton or clip pack - 5" mean radius @ 600 yards.
Mil spec for M80 Ball:
Bullet: 149 grain FMJ
Powder: 46 grains WC846, 41 grains IMR 4475, or 41.5 grains IMR 8138
Velocity = 2750 +/- 30 fps @ 78 ft.
Pressure = 50,000 psi max average.
Accuracy = Carton or clip pack - 5" mean radius @ 600 yards, link pack - 7.52" mean radius, max average at 600 yards.
For use in overhead fire applications the lot of M80 Ball also had to meet the above accuracy requirement with an additional requirement of no more than a 25" maximum extreme spread per target at 600 yards.
Mil spec for M118 Special Ball / Match
Bullet: 175 grain FMJ
Powder: 44 grains WC846 or 42 grains IMR 4895
Velocity = 2550 +/- 30 fps @ 78 ft.
Pressure = 50,000 psi max average.
Accuracy = Carton - 3.5" mean radius @ 600 yards
Mil spec for M852 Match
Bullet: 168 hollow point boat tail
Powder: 42 grains IMR 4895
Velocity = 2550 +/- 30 fps @ 78 ft.
Pressure = 50,000 psi max average.
Accuracy = Carton - 3.5" mean radius @ 600 yards
BLC-2 is the commercial equivalent of WC846. In the manufacture of a spheroidal ball powder like BLC-2 or WC846 the powder is manufacturered (in the past often from reclaimed/recycled cannon powder) and is then tested and sorted by grain size, burn characteristics, etc, to produce a particular lot of powder with the required/desired burn characteristics. The technician doing the mixing can also essentially custom mix a powder to comply with a customers specific requirements. This ability to easily mix and customize spheroidal ball powders is where the (entirely correct) idea develops that commercial powder manufacturers do not use the same "cannister" grade powders that are sold to reloaders by the pound or keg. They order a powder having certain specifications and the lot is custom made to those specs.
However, many of the commerical powders that are available to reloaders are essentially made to military specifications as is the case with WC846/BLC-2 and WC844/H335 and IMR 4895, which is of course IMR 4895 with the IMR standing for "Improved Military Rifle". However as with any powder from a given lot there is always some variation within the specification from lot to lot so you will want to start a bit under the starting load and then load up to the velocity desired. As a result the final charge actually used may be slightly higher or lower than the charge specified. It is the velocity and pressure that count, not the actual charge weight used. In short, the actual charge specified is of only general ball park use.
In addition, many military powders are available as either new surplus or as pull down powders. I am comfortable with new surplus powders, but the pull down powders make me a little nervous. You can take a large lot of powder and assuming it is well mixed, you can load it into several thousand rounds of ammuiiton and get reliable and predictable results. However, you can't neccesarily go the other way and pull the powder from several thousand rounds of ammunition made from several to several dozen different lots of powder made perhaps decades apart and then mix them together and expect the same consistent results. You are at best relying on having a (hopefully) large and (hopefully) random sample of powder from many different lots that you hope in the end will average out in terms of burn rate and consequently produce a powder lot with burn rates within the WC846 specification. That's a lot of hoping. On the other hand if the pull down powder is all from the same lot of ammunition all of which was made from the same lot of powder, you are good to go - but I have yet to find a pull down surplus powder supplier who can assure me of that.
In any event whether you use new or pull down surplus WC846, commercial BLC-2 or surplus or commercal IMR 4895, if you are creating an M59, M80, M118 or M852 clone, start 10% under the given loads and work your way up to the specified velocity incrementally while carefully monitoring for signs of excess pressure as all of the specified loads are fairly hot loads by most reloading standards.
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Tod Glenn
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