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Old March 26, 2010, 01:00 PM   #1
Boberama
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Cartridge, .50 Caliber, Ball, M2 ?

I can't find very much info on this load. I'm don't shoot .50, but I want to know how this performs. So far I've read:

Muzzle velocity: 3,050 fps or 2,930 fps, according to various sources, including the USMC.

According to TM 43-001-27 it is 2,810 fps at 78 ft from the muzzle.
But is that the muzzle of the M2HB?
The USMC says 3,050 fps, but how could it lose so much velocity in 78 ft?

Projectile Weight: I've read 710, 707.6, 720 and 750 grains. Which is it?

Powder charge: I know this one. It's 235 grains of WC 860.

Cartridge weight: It's 1813 grains.

Has anybody pulled a bullet or knows the correct weight?
Weight for M2 API would be appreciated as well.


One last thing, what is the cyclic rate of the M2HB?

I've read 500 rpm, 450-550 rpm, 450-500 rpm 450-575 rpm, etc.
Somebody should time it properly.
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Old March 26, 2010, 06:46 PM   #2
rg1
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Not too familiar with the M2HB but that is military specs for the M33-ball round. Reloading the 50 BMG with surplus WC860 and 647 M33 ball in civilian bolt actions and semi-auto's requires a reduction in powder charges as the 235 grain military charge will probably be too high pressure. Military data you refer to is in a 45" barrel and I've read that 40" is the optimal length for maximum velocity in 50 BMG. Also, velocity will be between 2600 and 2800 fps in 27-33" barrels at nominal charges of surplus 860 powder at 215-225 grains using M33 Ball. M33 Ball bullets were 647 grains but ball bullets are now available that weigh 690 grains or about the same as the 50 bmg M2 AP bullet. M8 API projectiles I've seen weigh anywhere from about 640 grains up to 649 grains with military spec at 643 grains. Surplus military powders such as WC860 and IMR5010 do vary in burn rate from lot to lot. You have to work up charges testing for pressure signs and velocity. One lot of surplus powder may give 2750 fps using WC860 at 220 grains and another lot may require 225 grains to get the same velocity. A fun caliber to shoot but expensive as component prices have doubled in the last few years. For instance, you'll only get about 33 loaded rounds per pound of powder,once fired military surplus cases are .055-.075 cents each. Primers are approx. $130 per 500 and add bullets, the high initial cost of the rifle and scope, and it adds up. There are several variants of the M2HB with different barrel lengths and rate of fire. Here's a good forum discussing the M2HB: http://m2hb.net/m2phpBB/index.php

Last edited by rg1; March 27, 2010 at 04:29 AM.
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Old March 26, 2010, 08:52 PM   #3
Scorch
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Rate of fire is adjustable in an M2. For M2HB, 450-575 rpm, aircraft model (lightweight air-cooled barrel) 750-850 rpm, up to 1,200 rpm for electric feed boosted aircraft guns.

The ammo is not designated M2, that is 30-06 ammo. The M2 fires M33 ball, M17 tracer, M8 armor-piercing, M20 armor-piercing incendiary. There is a new cartridge designated M933 SLAP-T explosive round designed for use against hard targets.

Projectile weight for different uses is different.
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Old March 28, 2010, 06:42 PM   #4
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50 BMG ball is designated, ball M2 .50 caliber and to really confuse you, AP is also designated with M2. They also use ball M33 .50 caliber as the latest designation for .50 Cal ball ammunition. It doesn't have anything to do with the caliber, the military just slaps on a designation for it.

There are many weights for 50 BMG ball because there are many different manufacturers, I've seen it as low as 625grs. and up to 710grs. Foreign stuff will fall into the same range, current ball ammo is running right about 700grs. The reason for the changes over the years is to keep it shooting within the same arc as the rest of the ammunition being fired through the M2.

SLAP or SLAP-T is not explosive, SLAP is a Sabot Light Armor Piercing (T-Tracer) round w/o any explosive material. Mk-211 Mod 0 is Raufous which is an explosive armor piecing round that has a tungsten penetrator in it's core.

M8 API runs right around 623grs. but can vary due to different manufacturers, just like ball ammo.

The M2 will run anywhere from 450-550 RPM, ammo and headspace and timing will play a roll in how fast it will shoot. The M3 aircraft .50 is a whole other issue, FN's new M3 will run 1,200 RPM all day long. There's alot of history in the .50 and will take alot of reading to get the idea behind all the different incarnations of it.

Here's some good reading on ammo, http://www.inetres.com/gp/military/i...g/50_ammo.html http://www.olive-drab.com/od_firearms_ammo_50cal.php http://en.wikipedia.org/wiki/.50_BMG http://www.my-bullet.com/us/Latest/5...llet-info.html http://en.wikipedia.org/wiki/Raufoss_Mk_211 http://www.fas.org/man/dod-101/sys/land/slap.htm
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Old March 28, 2010, 07:02 PM   #5
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Last edited by noyes; March 30, 2010 at 09:20 AM.
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