Well, the board is either fixed, or it's going to run terribly. Cross your fingers and hope for the best. I'm at my technical limit right now.

IMR-7383 in the .50 Alaskan

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Rapidrob
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IMR-7383 in the .50 Alaskan

#1 Post by Rapidrob » Mon Jul 16, 2018 5:08 pm

I've had so much good luck accuracy wise using the .50 Spotting Powder IMR-7383 in all sorts of calibers I thought I'd try it in my .50-110-750 Rolling Block Rifle.
I've had really good results shooting the 50 BMG projectiles using IMR-3031 that I thought I'd try this powder with a heavy cast lead bullet.
There is a bullet trap in my reloading shop so working up a load is just a few steps away from the loading bench.
After crunching some numbers I found that a good starting point would be 40 grains of IMR-7383 under one of my cast 660 grain, .512 flat base hard lead bullets.
This proved to be OK but on the weak side. Lots of unburnt powder. I increased the load to 43 grains and got a better burn,but still some unburnt powder grains in the bore.
46 grains was better still with a couple of stubborn grains refusing to ignite. A load of 48.5 grains burned cleanly and recoil was manageable, as if I was shooting a 12 Gauge slug out of a riot shotgun. 50 grains was max load with unpleasant recoil with this rifles steel butt plate. The 50 grain load was being compressed to where any more powder my be in danger of a pressure spike, which with this powder you want to avoid at all cost.
I'm hoping that this load will do well at long range. I fired five rounds into the bullet trap;afterwards cleaning the rifles bore. No signs of leading.
Estimations show the bullets to be around 1,600 fps. Not laser fast,but not really poking along either.
Here is the case and bullet. Above is a 220 grain .30-40 Krag bullet.
20180716_142452.jpg
Tin Can Sailor
'Nam Vet
NRA Endowment Member
President New Mexico Military Surplus Rifle Pistol Shooters

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Re: IMR-7383 in the .50 Alaskan

#2 Post by Rapidrob » Mon Jul 23, 2018 5:09 pm

I shot the rifle this past weekend at 200 and 500 yards from the prone. At 200 yards the rifle groups very well. At 500 yards the bullet has gone sub-sonic and the group opened up.
While I got three good hits,several of the rounds were just off target a few inches. I'm going to increase my load to 50 grains and see if that helps with better accuracy. Thee fired rounds show no signs of pressure problems.
The bullet strikes with a tremendous force sending shrapnel in all directions. A cloud of dust is kicked up at the base of the supporting poll obscuring the target for a few seconds.
Here is the 500 yard target with three hits. I bracketed the target with one shot high on the left side of the head, one low in the left kidney and the third almost center in the target.
500 yards with 50 110 750.jpg
Recoil is not sharp.It is a heavy shove backwards.
Tin Can Sailor
'Nam Vet
NRA Endowment Member
President New Mexico Military Surplus Rifle Pistol Shooters

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