Low pressure-full cases - 24hourcampfire

Ken, I have followed your ideas about achieving low pressure with full cases,but I am wondering if you could offer suggestions on how this might be accomplished. I am just a beginning loader and have worked up a load for the 7mm STW at 7mm Rem Mag velocities (and I assume lower pressure) which provides very good accuracy. However using IMR7828 the case is perhaps 80% full, though still within the starting load suggestion from the Nosler manual. How do I go about finding a powder that gives me a full case and lower pressures? I could buy all of the different powders and experiment, but I was hoping you might offer a better suggestion for achieving this.
 
 Thanks,
 Rick

I have no experience with the 7mm STW, but the computer tells me that the charges and the powders that I'm going to list will produce the velocities that I'll also list, at 50,000 lb/sq in. or less (assuming 160-grain bullets seated 0.350 inch and a 26-inch barrel).
 
 87.3 gr Hodgdon H-870 (98.2% case fill) -- over 3,000 ft/sec
 79.6 gr Reloder 25 (94% case fill) -- over 3,000 ft/sec
 86.9 gr Vihtavuori 24N41 (95.7% case fill) -- over 3,000 ft/sec
 79.1 gr Hodgdon H-1000 (90.2% case fill) -- over 3,000 ft/sec
 90.7 gr Hodgdon H50BMG (100% case fill) -- under 3,000 ft/sec

Ken, I'd be very interested in the same question in regard to the .270 WBY mag, for the same reasons. I use the 130 and 150 nosler partitions primarily. It seems a bit odd to me that so little data is available for the very slow powders in this cartridge as they would seem to be the best suited for it.

Thank you, you have saved me a lot of time. I will work up some loads with these powders and let you know how it turns out.
 
 Thanks,
 Rick

If I had a .270 Weatherby Magnum and were seating 150-grain Noslers 0.593 inch into the necks, I'd expect these charges of these powders to give me about 3,000 ft/sec (give or take about 30 ft/sec) at about 50,000 lb/sq in.
 ("xx%" means percent of space filled, between web and base of seated bullet)
 
 Ramshot Magnum --- 69.7 grains --- 94.3%
 Reloder 25 -- 68.9 grains --- 100% --- (49,000 lb/sq in)
 Norma MRP --- 64.9 grains --- 91.7%
 IMR-7828 --- 64.3 grains --- 93.9 %
 Hodgdon H-1000 --- 68.4 grains -- 96%
 Reloder 22 --- 63.5 grains --- 90.8%
 Hodgdon H4831SC -- 65.0 grains --- 90.9%

Ken, Thanks. Most of those load/velocity combinations pretty well track my data although they are in the starting load range in the manuals. The two big exceptions are the H1000 load which is 6.5 grains under Hodgen's starting load of 75 grains which only produced 2800 in my 24" barrel, and the RL 25 load, as I didn't hit 3,000 fps with RL25 until 72 grains, and the accuracy, (and standard deviation), didn't settle down until 75 grains which still doesn't fill the case to the base of the neck, and is going at 3160. This is the load I'd been calling a "good load", I wish I knew what the pressure was. I'm not too concerned about the velocity within a few hundred fps, But I am concerned about the accuracy and like the idea of the longer point blank range as that was the idea behind this rifle in the first place.