I managed to get to the range today to test some new reloads for my Bergara .357 magnum.
I've had a bit of reloading experience, but up until recently I've just followed common recipes. However, I now have some 200 grain cast bullets I want to shoot at subsonic velocities, and ADI (my powder supplier) has no tested recipes for these projectiles.... so this is new territory for me. Thanks to folks here, and elsewhere, I have data for 200 grain projectiles using other powders, so I carefully compared the powders and data and came up with my own loads. I figured that a lot of the published data would have been for revolvers, and I would be using a relatively strong rifle for my load testing so I should be fairly safe. I reasoned that if the same model of rifle can also be chambered in .308, 7mm-08 and 45-70, then it should be strong enough for experiments where the desired outcome was a modest speed with a lead projectile.
I am likely to get other powders in the future, but meanwhile I have APS350 (similar burn rate to 'Red Dot'), Trail Boss, and AP70N (similar burn rate to 'Unique'). I have been using CCI 400 small rifle primers.
All powders give me acceptable hunting accuracy with 125 grain and 158 grain lead projectiles when shot at subsonic speeds.
I don't know if it is permissible to post personal load data on this site, so if it isn't allowed, feel free to delete it or tell me to edit it. I should note here that my batch of powder, my scale calibration and my methods may be different to what other folks may have or do, so always consult the manufacturer's reloading data before deciding how much powder to use. And be aware that some firearms are stronger than others. Never make assumptions about the substitution of projectiles, primers or powder.
The 200 grain cast projectile is still challenging me. I figure that the 16 inch twist in the Bergara barrel should work with this bullet. I have cut a cartridge case off at the point where the base of the properly seated 200 grain projectile would sit, so I was able to see what the maximum capacity was for each powder. There was plenty of space for the APS350 and AP70N maximum loads, but it limited Trail Boss to 4.3 grains.
According to my Dad's old Chrony, 4.2 grains of Trail Boss gave me a velocity from 803 to 846 fps. This gave me a three shot group of 1.25 inches at 25 yards. 4.3 grains resulted speeds of 845 to 878 fps, but the group spread out to around 2.5 inches.
4.2 grains of APS350 propelled the projectiles at 911 to 932 fps but the 25 yard group was spread over 5.4 inches. Not good. The primers appeared to be slightly flattened with this load, so I wouldn't load more of this powder even if the accuracy had been promising.
5.4 grains of AP70N gave speeds of 1041 to 1074 fps. This gave me a 3 inch group at 25 yards. Although the Trail Boss loads gave me better accuracy, I want all the subsonic power I can get so I raced home from the range and loaded up some cartridges with just 5 grains of AP70N. The velocity of these ranged from 1023 to 1064 fps... and they gave me a 1.8 inch group at 50 yards, which equates to a group of 0.9 inch at 25 yards. This is getting better.
Oddly I load 158 grain cast bullets with 5 grains of AP70N also, and according to my notes these travel at 1036 to 1093 fps which isn't a heck of a lot faster than the 200 grain bullets with the same load.
I think my next step will be to load cartridges with the 200 grain lead bullets and try a slightly lower load of AP70N... maybe 4.8 grains... to see if accuracy improves. I know I could experiment with lead hardness and maybe use jacketed projectiles, but I want to use soft lead as it is commonly available and has the greatest chance of mushrooming when it hits (although I am not expecting great expansion at 1000 fps).
In case it is of interest to anybody, here is how I lubricate my cast bullets: At present I am happy with 'Fryxell Lube"... a 50/50 mix of beeswax and Sta-Lube Moly-Graph grease (which I think I bought from Mitre 10). I mixed the ingredients carefully on a stove outdoors (it smells pretty bad)... then I poured some into an old Elastoplast tin. I load the cartridges with powder, then start the bullet into the case with the lower grease ring still showing. I then pack the lube into the grease ring (and often the crimping ring) using a painter's plastic palette knife. I remove excess lube with the edge of the palette knife, followed with a careful wipe with a bit of paper towel.... taking care not to remove lube from the rings. I can then seat the bullet knowing that the powder cannot come into contact with the lube.
I know that tumble lubing or sizer lubing would be quicker... and better for someone shooting a heap of bullets, but I don't shoot a lot, I don't like the stickiness of Alox lube, and I have no desire to own a bullet sizer. I've tried pan lubing but I have come to prefer my current method.
Applying the lube:
Excess lube removed prior to seating to correct depth:
The loaded 200 grain bullet next to a 125 grain bullet. The big bullet sticks out too far to feed through the action of my Rossi lever action... but it still fits the chamber without jamming in the rifling.
I'd like to be able to have a load for the 200 grain projectiles that will consistently give me a group of under 1.5 inches or smaller at 50 yards at a velocity of between 950 and 1050 fps. My .22 rimfires and my .223 will shoot much better than this, but I don't yet have the experience to know what a reasonable expectation of accuracy should be from a .357 with slow soft cast bullets. I might get to try some new loads this week.
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