BeeMan
10-11-2005, 05:14 PM
Surplus 7383 has already given impressive accuracy in full case 243 loads with the Sierra 70 HPBT. My challenge now is to find a cast load for 30-06 with this powder. Boolit is the RCBS 180 FP in air cooled wheel weights, sized to the throat at .310, with Felix lube. Seating to the crimp groove just sets the nose into the lands.
First attempts were 30 to 34 grains in 1 gr increments, 5 shots each. Average velocity ranged from 1720 to 1946 fps, about what I was looking for. No leading and no unburned powder in the bore. Lube star at the muzzle seems about right. Groups were about 1 to 1.5 inches horizontally at 100 yards, scoped and from the bench. Unfortunately, vertical dispersion stretched out to 3 to 3.5 inches. I took this as a sign of ignition issues, since ES was as much as 63 fps for 5 shots.
Next step was to take up airspace and reduce potential light off variation. The series was repeated using ground wheat bran filler. Just enough was added to fill the powder to bullet base space without compression, since others have mentioned 7383 spikes quickly on overloading. About 1.2 to 1.4 cc of filler was required. Groups were more rounded but significantly larger at 2.5 to 4 inches. Surprisingly, velocity dropped and ES increased, compared to the same loads without filler. There was also a trace of residue in the bore after each shot, presumably residual filler.
Am I chasing the right idea that something needs to help ignition? The Bf definitely absorbs energy and hurts uniformity. Maybe it is too much on top of the powder column, filling the nearly 1/2 inch space above 30 to 34 grains of 7383. Regardless of why, it doesn't work. I've successfully used dacron with 820 surplus, but am not sure about using it to fill the smaller space above a rifle powder. I'm using Winchester LR primers, and have Remington 9 1/2 available.
The small horizontal spread on the unfilled loads seem to indicate this wants to work. I'm stubborn enough to pursue making 7383 work instead of buying one of the slow surplus ball numbers. The 7383 won't allow double charges like 820 and is inexpensive. Besides, I've got more 7383 than I will burn in the 243, given the cost of jacketed. I'm scratching my head where to go next.
Thanks for listening, ideas anyone?
BeeMan
First attempts were 30 to 34 grains in 1 gr increments, 5 shots each. Average velocity ranged from 1720 to 1946 fps, about what I was looking for. No leading and no unburned powder in the bore. Lube star at the muzzle seems about right. Groups were about 1 to 1.5 inches horizontally at 100 yards, scoped and from the bench. Unfortunately, vertical dispersion stretched out to 3 to 3.5 inches. I took this as a sign of ignition issues, since ES was as much as 63 fps for 5 shots.
Next step was to take up airspace and reduce potential light off variation. The series was repeated using ground wheat bran filler. Just enough was added to fill the powder to bullet base space without compression, since others have mentioned 7383 spikes quickly on overloading. About 1.2 to 1.4 cc of filler was required. Groups were more rounded but significantly larger at 2.5 to 4 inches. Surprisingly, velocity dropped and ES increased, compared to the same loads without filler. There was also a trace of residue in the bore after each shot, presumably residual filler.
Am I chasing the right idea that something needs to help ignition? The Bf definitely absorbs energy and hurts uniformity. Maybe it is too much on top of the powder column, filling the nearly 1/2 inch space above 30 to 34 grains of 7383. Regardless of why, it doesn't work. I've successfully used dacron with 820 surplus, but am not sure about using it to fill the smaller space above a rifle powder. I'm using Winchester LR primers, and have Remington 9 1/2 available.
The small horizontal spread on the unfilled loads seem to indicate this wants to work. I'm stubborn enough to pursue making 7383 work instead of buying one of the slow surplus ball numbers. The 7383 won't allow double charges like 820 and is inexpensive. Besides, I've got more 7383 than I will burn in the 243, given the cost of jacketed. I'm scratching my head where to go next.
Thanks for listening, ideas anyone?
BeeMan