50BMG (50DTC) reloading problems

[LDBennett]

To start with and because I live in CA my 50BMG is really CA legal 50DTC, made from 50BMG cases with the shoulder pushed back and shorter by about 0.1 inches. Over the last couple of years we have been building the BOHICA bolt conversion for the AR-15, reloading for the gun, finally shooting the gun, and fire forming brass.

Along the way I bought two different sources of brass: 150 once fired Lake City military surplus (two batches...50 then 100 just now), and 50 new CBC made in Brazil. We have encountered min-problems along the way and have overcome them. But recently two problems have surfaced that need high lighting.

The first is that the new CBC brass does not conform to 50BMG standards as the wall thickness is too thin. The result is the sized case has a throat inside diameter that is the same as the bullet and assembled rounds have the bullets held in by only the crimp..... NO neck tension. I investigated all options and decided to discard the CBC cases (@75 cents each, ouch!) after the first shooting (actual brass salvaged it).

The replacement was 100 once fired cases of 50BMG MIL Surp Lake City, mostly 2008 and 2009 with a couple of 2007 head stamps. Then I ran into two problems on a couple of cases (four to be exact).

The first problem was the primers in two cases. The bottom of the cup separated from the rest of the cup while removing the primer so that a rim of primer cup is left in the case held in by the primer staking. I dug at it, tried to probe under its edge, chamfered away the staking with no luck. Anyone got any ideas as to how to get the remains (the rim) of the primer out of the case's primer cavity?

During preparations of the case I size them in the 50 DTC sizing die. That pushes the shoulder back to 50DTC standards. For the 150 some cases like this I have not annealed the throats of the cases before sizing and have lost none (except these two I site here) in either the sizing operation or during fire forming. These two case would not completely enter the sizing die (I stopped the force when it got excessive). One cracked on the shoulder and the other would just not go into the sizing die all the way. They were from the same head stamp range as all the other 100 recently purchased cases. What happened?

My guess is that somehow they needed annealing but why? 148 cases processed the same way did not. What would cause these cases to get hard in one firing. Could they have missed the annealing at Lake City or is there some 50BMG firearm that is particular rough on them so as to work harden them with one firing? They look exactly like the rest of the lot. Anyone got any ideas?

In conclusion, the reforming of 50BMG to 50DTC harvested all but four cases out of 150 so that can not be all that bad. And don't buy any CBC 50BMG as ammo or as a component case and expect it to be reloadable. Leave it to the Brazilians to screw it up. But this kind of falls in line with their Taurus and Rossi guns. If I had a Springfield gun made in Brazil I'd be worried.

LDBennett

[JLA]

Originally Posted by LDBennett

To start with and because I live in CA my 50BMG is really CA legal 50DTC, made from 50BMG cases with the shoulder pushed back and shorter by about 0.1 inches. Over the last couple of years we have been building the BOHICA bolt conversion for the AR-15, reloading for the gun, finally shooting the gun, and fire forming brass.

Along the way I bought two different sources of brass: 150 once fired Lake City military surplus (two batches...50 then 100 just now), and 50 new CBC made in Brazil. We have encountered min-problems along the way and have overcome them. But recently two problems have surfaced that need high lighting.

The first is that the new CBC brass does not conform to 50BMG standards as the wall thickness is too thin. The result is the sized case has a throat inside diameter that is the same as the bullet and assembled rounds have the bullets held in by only the crimp..... NO neck tension. I investigated all options and decided to discard the CBC cases (@75 cents each, ouch!) after the first shooting (actual brass salvaged it).

The replacement was 100 once fired cases of 50BMG MIL Surp Lake City, mostly 2008 and 2009 with a couple of 2007 head stamps. Then I ran into two problems on a couple of cases (four to be exact).

The first problem was the primers in two cases. The bottom of the cup separated from the rest of the cup while removing the primer so that a rim of primer cup is left in the case held in by the primer staking. I dug at it, tried to probe under its edge, chamfered away the staking with no luck. Anyone got any ideas as to how to get the remains (the rim) of the primer out of the case's primer cavity?

Chuck em up in the lathe and turn the 'ridges' off.

During preparations of the case I size them in the 50 DTC sizing die. That pushes the shoulder back to 50DTC standards. For the 150 some cases like this I have not annealed the throats of the cases before sizing and have lost none (except these two I site here) in either the sizing operation or during fire forming. These two case would not completely enter the sizing die (I stopped the force when it got excessive). One cracked on the shoulder and the other would just not go into the sizing die all the way. They were from the same head stamp range as all the other 100 recently purchased cases. What happened?

My guess is that somehow they needed annealing but why? 148 cases processed the same way did not. What would cause these cases to get hard in one firing. Could they have missed the annealing at Lake City or is there some 50BMG firearm that is particular rough on them so as to work harden them with one firing? They look exactly like the rest of the lot. Anyone got any ideas?

Sounds like they were just work hardened, I would have re-annealed them before trying to size them thru the DTC die anyway.

In conclusion, the reforming of 50BMG to 50DTC harvested all but four cases out of 150 so that can not be all that bad. And don't buy any CBC 50BMG as ammo or as a component case and expect it to be reloadable. Leave it to the Brazilians to screw it up. But this kind of falls in line with their Taurus and Rossi guns. If I had a Springfield gun made in Brazil I'd be worried.

LDBennett

Hows that beast group LD? I dont remember if youve posted pics of the groups yet or not. I know youve been working on it for about 2 years now.

[USMCSpeedy]

It could be just the difference in the weapon they were originally fired from. Some military weapons have seen alot of use and military specs usually run a little on the loose side to account for dirty combat conditions. With the price of brass what it is, it sucks that you have to loose a few but at least it was only a few.

[LDBennett]

We skipped that step (What???).

Finding a place to shoot 50BMG (50DTC) is a problem where I live. No range will have us that is anywhere close (less than 100 miles). So we go to the edges of civilization to the open desert (almost my backyard but still 50 miles away). The biggest driver in all this is my son-in-law who loves to shoot a metal at great distances. I shoot it some but mainly I am just the reloader and gun builder... an enabler, so to speak. Our first outing we placed a truck brake drum at 220 yds and hit it with every shot after zeroing the scope. We started shooting at objects of interest with me observing the results at ranges over 600 yds. The last outing we were shooting at 750 yds at bus brake drums. We thought we were hitting them regularly but a close inspection says we were not. We need a better target and we are working on getting a round armor plate disk, about 15 inches in diameter, hanging from chains on a stand. With that we will be able to easily see hits.

We have not been very scientific about this but we are having fun none the less.

We now have 100 LC cases to fire form (again!). We are keeping the loads uniform between fire forming and real ammo and have seen no real difference in observed accuracy. The recoil is harsh enough so we don't really want to go to a max load.

Without actually shooting on paper I can not comment on whether the lack of neck tension is effecting accuracy or not. But no neck tension is wrong and I do not want that so the CBC brass is going to be gone once empty and the 100 LC cases will replace it with the next reloading session.

LDBennett

[LDBennett]

I was lathe trimming my 50DTC cases yesterday (the lot is 100 cases) and wouldn't you know it. My lathe motor started making funny noises at turn on and finally quit starting up. I changed the motor control switch (had a spare) but no luck. Now I have to pull the darned motor off the lathe and try to determine what is wrong and see if it is repairable. The lathe is stuck up against the wall and weighs a 1000 pounds so I'll have to work the motor out in those cramped spaces. I got down to the last 1/2 dozen cases. Oh well, it keeps me out of the bars and away from the babes.

DARN! Thank you China! (Chinese made lathe)

LDBennett

[JLA]

too bad Lee precision doesnt make lathes eh?

[LDBennett]

I think it says LEE/Smithy on the lathes nameplate (??).

LDBennett

[The_Rifleman]

Originally Posted by USMCSpeedy

It could be just the difference in the weapon they were originally fired from. Some military weapons have seen alot of use and military specs usually run a little on the loose side to account for dirty combat conditions. With the price of brass what it is, it sucks that you have to loose a few but at least it was only a few.

That was also my conclusion.