New to reloading 50BMG, but I figured I should start trying soon.
For a lot less than the price of Hodgdon 50bmg powder, I can get WC870 or WC872. Slightly more for WC860.
Any experience loading with these powders? Recommended starting loads? Thinking of reloading with one of these surplus powders and pulldown bullets.

I mainly use 210  grains of wc 860 and like it.

If your reloading for a bolt rifle with a 700 grn projo, start with 215 grains of any of those powders and work your way up from there.
For a semi, load a couple with 218 grains and see if it'll cycle the action. Work up from there.
Surplus/Pulled powders all burn differently.
If you can, get powders with the same lot # and you won't have to do test loads for each container of powder.
Good Luck and Happy Shooting !

I use WC860 for most all 50 BMG bullets. Surplus powder can vary in burn rate from lot to lot number. Buy a quantity that will last a good while. Only about 33 rounds per pound of powder. Your 860 could be faster or slower than mine. For 643-650 grain bullets a start charge of 210 grains and work up. Usually you'll find a good accurate load from 215-220 grains. For heavier 690-750 grain bullets a start charge of 205 grains of WC860 would be a good safe range to start. I'd pick WC860 but the other powders would work well too but they tend to be slower than 860.  You can work up in increments of 3-5 grains and maybe tweak your loads when you find an accurate level. The sad thing is that right now the availability of surplus bullets is at a decade low. Can't find ball surplus or new FMJ bullets anywhere.

I was getting over pressure signs at 215 grains of WC867 behind API's in my AR-50.  I got the powder dirt cheap from Wideners several years ago when they had quite a batch of it. It was supposed to be virgin and seemed to be.  Most here seem to be able to load that same powder several grains higher than I can.  Maybe it's because I live and shoot at a  moderately high elevation??  I would start at 210 with 650 grain API's and work up from there just to be safe.  I believe one poster here said he started at 210 of WC860 or WC867 with API's and settled with it right off the bat.  I'm currently loading 212 grains of WC867 behind API's with no over pressure signs and averaging in the low 2,700's in velocity 10 feet from the brake.

Same here with the 872 i got from them. 220gr popped a primer and cut a line in my bolt. Not bad but its there. I run 210 of the 872 and my api's in my ar50

I use 500gr of 872 under a 1600gr projectile in my 20x102

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Much appreciated! I just bought some M33 649gr pull down bullets and some pulldown WC860 powder. I'll definitely start at 210 grains and work up gradually. With 50 BMG loads... do you guys just go up 1 grain at a time? Or should I split it into smaller increments like 0.5 grains? Kinda bonkers with this much powder lol.
I'm ideally hoping to duplicate Federal XM33 ammo... but I'm not sure if I could safely push the bullet fast enough to match it. Reason I'm a bit concerned is because I read the pulldown powder has as much variation as 150-200 fps!

Going to publish some of my findings on WC860 for my M82a1 and M107a1.
I'm currently having trouble with the M107a1 cycling. I do 5 grain increments.

             M82a1  29"        
M2 AP 690gr      215gr cycles  
M8 API 649gr     220gr cycles  
M1 I 622gr        225gr cycles    
M33 SA  690gr   210gr cycles  
M17 T 643gr      210gr cycles    
M33 LC factory   cycles

           M107a1 20"
M2 AP 690gr     215gr cycles
M8 API 649gr    225gr Fails started at 205gr next try 230gr
M1 I 622gr        225gr Fails started at 215gr next try 230gr
M33 SA  690gr  210gr Fails started at 205gr next try 215gr
M17 T 643gr      210gr Fails started at 205gr next try 215gr
M33 LC factory   cycles        


Is there that much diffrence in the M82a1 vs the M107a1 that I cant use the same load data? or is there something wrong?

The LC XM33 I have is warm and will give my swipes in my M107.  I have some of the WC 867 and it cycles as low as 210 grs.  I have run up to 225 gr with APIs but that is a warm load.

I used WC860 with 650 gr projo's. Worked fine. think i settled on 216 grains. But used H50BMG with hornady 750 gr A-Max. That stuff is a little stout. Definitely know when you shoot with H50BMG.

I'm running 218grns. behind API through my AR50 and 82A1.No issues.

Only wish I had bought more.