Loading 50BMG Cast

Bob J

Bob J

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Ok, this is a new project and pretty much a work in process but thought it worth sharing what Mark and I have been working on....[smile]

Got a good deal on a BOHICA and then had to figure out how to keep it fed.....[smile]

Bohica2.jpg


Reloading is a no brainer but given Mark's casting expertise thought it would be worth seeing what we could do loading cast for the beast....

Was able to get an 875 grain 50BMG cast mold from a NOE group buy over on Cast Boolits.... Casts a pretty good looking boolit..... Here it is compared to one of our cast 308 rounds.....

50BMGCast308.jpg


50BMGCast1-2.jpg


Ordered a .512 sizing die for my star from Lathesmith and gas checks from Blammer over on the cast boolits site..... Lubed with Lars Carnauba Red and gas checked the boolit consistently weighs just over 880 grains.....
 
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Brass

Brass prep is a real workout.....

Started with tumbling in SS media.... Comes out really nice and clean both inside and out.....

SSMediaTumbling.jpg


SSMediaTumble2.jpg


Picked up a nice used LNL 50BMG press..... Here it is with the sizing die....

P1010050.jpg


All the dies for this are monsters..... This is the sizing die....

FLSize.jpg


As was noted in the other 50BMG thread, sizing is a real workout.... I'm full length sizing so when I lube the brass (imperial sizing wax) I make sure that I lube inside the neck (with a Q tip) as well as the full length of brass all the way down to the base....

After sizing I trim to 3.92" using a Dillon dedicated trimmer.....

CaseTrim.jpg


After trimming I ream the primer pocket.... This also removes the factory crimp.....

PPReamSize.jpg


I'm a big believer in using M dies to flare my brass when loading cast.... For this baby I had to custom make my own M die..... Picked up a used 50BMG seating die and had a custom expander plug made for it..... Here it is loaded in the press....

MDie1.jpg


Does a beautiful job of expanding the brass so that the bullet will seat straight and with minimum brass run out..... Here I am checking the depth of the expander ball setting....

MDie2.jpg


At this point the brass goes back into the SS media tumbler to clean the primer pocket and remove any residual lube from inside the case... This is as far as I was able to go today so will post again when I actually build the loads.....[wink]
 
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lord1234 said:
This is awesome. Have you calculated your total cost per round?
Click to expand...

Not yet.... Still need to do load development for this beast so will have to see but it sure will be a lot cheaper than buying factory loads...... The dies and stuff can be pricey but I've bought all used stuff (except for the sizing die and the M die plug) so that helps a lot....
 
Fixxah said:
Is the impact puller for that as big as a sledge hammer?
Click to expand...

One would think so. [smile] I don't think one is made for the BMG, bullets are collet pulled.
Its bad enough trying to remove one if it squibbed and stuck in the barrel.

I use the 1/2 inch opening on a tubing flaring tool. Works like a collet with minimal marking of the bullet.
 
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Patriot said:
I saw a completed round last Saturday and that is truly an awesome cartridge, and a very nice job putting that together Bob.

Are you using 50/50 water dropped in that?
Click to expand...

Thanks! Am starting off with pure WW water dropped until I can get a good feel for how it shoots..... Would like to go 50/50 since at 880 grains each, these really drain a pot fast.....
Will post an update as soon as I can get some additional load development done..... Sorry for the delay guys but really want to get this one right....[smile]
 
For those of us who have never shot cast rifle rounds, or a .50 - how can you make a .50 BMG round slow enough that the projo doesn't just shear thru the rifling?
 
55_grain said:
For those of us who have never shot cast rifle rounds, or a .50 - how can you make a .50 BMG round slow enough that the projo doesn't just shear thru the rifling?
Click to expand...

Based on my understanding, successfully loading/shooting cast favors the heavier weight bullets.... The extra mass results in a slower acceleration and a slower MV..... A cast bullet "skldding" or effectively distorting it's engagement with the lands are associated with a couple of factors that are very controllable by a caster/reloader.... The first and foremost is proper fit..... This bullet is sized .002 over the slugged bore diameter so I am sure that I get maximum engagement.... The second is the powder being on the slower side of the available spectrum.... For these loads I am using WC872 which is a very slow powder typically specifically used for 50BMG.... The last is bullet hardness.... This is the question Patriot was really asking..... I am starting out with my "go to" hard alloy which is pure wheel weight alloy that has been water dropped.... After a week or two of aging these typically come in at a 20+ BHN hardness... The water dropping (vs air cool) causes the hardness to increase from about 10+BHN to the 20+BHN.... I can go harder using linotype/monotype but those bullets tend to be more brittle and potentially open up a different set of problems....

So, I am controlling two of my primary factors by sizing the bullet to the barrel properly and using a relatively slow power for reloading..... I am hedging my bets by going with a hard alloy selection but will experiment later to see if I can back off a bit to extend my stash of ww alloy.... I did this when I loaded for the 500 mag and found that with a gas check to protect the base of the bullet I can pretty much use any alloy including some of the softer mixes for all except the spire point.... That one needs the harder alloy to keep the sharp tip from being damaged during handling.....[wink]
 
55_grain said:
For those of us who have never shot cast rifle rounds, or a .50 - how can you make a .50 BMG round slow enough that the projo doesn't just shear thru the rifling?
Click to expand...

Other than the things that you can control in the reloading process (all the things Bob mentioned), bigger bullets inherently are more conducive to cast. The way it was explained to me is that it has to do with bearing surface between the ogive and the tail. The bigger the caliber the more area engages the rifling.

where A = Bearing Surface Length * Bullet Diameter * PI()

eg (specific bullets will vary).
for .224 => A = 0.18 sq. in.
for .308 => A = 0.37 sq. in.
for .458 => A = 0.794 sq. in.

So even though the .458 bullet has twice the diameter of the .223, it has almost 4.5x the bearing surface so it can be pushed faster w/o slipping the rifling. It makes sense and empirically I have noticed that I can push bigger casts faster than smaller ones. Clearly not as fast as jacketed.
 
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Probably a good time to resurrect this thread..... Was able to do some load development at HSC a few weekends ago and I have to say this boolit shoots pretty sweet loaded over 190.0 grains of WC872..... Much less than that I was getting indications that the neck wasn't fully seating so would consider this a minimum load.... Might be able to push it more but this load was very accurate and I wanted to load a hundred rounds or so just in case anyone wanted to shoot Thor at the pumpkin shoot.....[smile]

Actual cost per round for this load is:
Primer = $.20 (CCI)
Powder = $.14 (Was able to get WC872 for $39/8lb Keg shipped w/ hazmat)
Gas Check = .03 (Buying them for now but will probably go the FCIII route in the future)

$.37/round is not to shabby.....[wink]
 
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That is a great deal. How much for milsurp FMJ if one were to go that route?

Sent from the Hyundai of the droids, the Samsung Replenish, using Tapatalk.
 
Fixxah said:
That is a great deal. How much for milsurp FMJ if one were to go that route?

Sent from the Hyundai of the droids, the Samsung Replenish, using Tapatalk.
Click to expand...

Have seen them for $225/500 for 690GR FMJBT (South African New) so the cast is a significant cost savings per round...... Now if only the primers weren't so expensive.....[crying]
 
BUMP for those of us about to start casting and reloading the cast lead bullets for this caliber.

For trimming to length, I plan on getting the Giraud trimmer insert for 50 BMG.
$75 for a trimming solution is a reasonable deal:
GTC Trimmer

Also, Bob J suggested "buckshot" at castboolits for making the custom "M" die.
I have a copy of Bob's pdf file, showing dimensions. Thanks, Bob.
 
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