Need start loads for 50 bmg 646 gr api's

[USMC87]

I would appreciate a starting load for 50 BMG 646gr api's loaded with surplus 860. I appreciate any and all help!

[Outpost75]

What are you shooting these in? Barrett or?

[USMC87]

Armalite single shot.

[SOFMatchstaff]

The factory load is 235 grs WC860 for several different projos. You can start at 225 and work up for accuracy.
Make sure the primers are seated properly..

[Outpost75]

WC860 is LC pulldown ball powder from Ball M33 and API M8. It is said that it can be loaded using Hodgdon H870 or AA8700 data, but it burns a little faster. The charge for M33 is nominally 235 grs of WC860, the charge being adjusted at the loading machine to attain 2810+/-30 fps from the test barrel with a max sample average pressure of 55,000 psi. Since you don't need to worry about semi-auto function I would work up from about 200 grains until you get good grouping and don't worry about velocity. I wouldn't reduce the Ball powder more than this without using a 5 grain Dacron loose filler tucked into the case neck before seating the bullet to take up the excess free airspace in the case, as ignition otherwise becomes erratic.

If want to shoot with a suppressor the common extruded 7.62mm rifle powders like IMR4895, IMR4064, RL15 or Varget can be loaded at about 1/2 of the charge weight of a full-charge load of the slower Ball powder, reducing down to about 110-130 grains, using 10 grains of loose Dacron fill with M33, API M8, or APIT M20 which is much fun to shoot and gives ballistics similar to the M48 spotting rifle cartridge. Makes a good cast bullet load for cheap shooting. Tom at Accurate can cut you a mold.

[USMC87]

I really appreciate the help guys!

[Japlmg]

I use 215 grains of WC860 under both Ball and API in my AR-50.
I get about 1 inch groups at 300 yards; by weighing every powder charge to +/- 0.1 grain, and weighing the projectiles, segregating them to +/- 1 grain weight.
It also helps to use cases with the same head stamp (date and manufacturer).

[USMC87]

Thanks for the information.

[chic]

Outpost 75, it sounds like you have experience with Dacron in the 50, which I assume has a muzzle brake. I have been wondering about this and found this post. There have been no problems wiht the Dacron catching in the brake?

[Outpost75]

Outpost 75, it sounds like you have experience with Dacron in the 50, which I assume has a muzzle brake. I have been wondering about this and found this post. There have been no problems wiht the Dacron catching in the brake?

This small amount of Dacron should be completely consumed upon firing. If any is deposited onto the muzzle brake it will probably be as a smoky film which can be cleaned off with a brush using Mil-C-372B or Kroil. If you see any visible "fluff" being blown out the muzzle, then reduce the Dacron fill until no longer occurs.