17 March 2024

Weird Gun Idea - Triple Seven in .357 Magnum and .38 Special

 Since I've been on a kick lately on stuffing Triple Seven into whatever case, I figure that maybe I should try .357 Magnum and .38 Special. I would very much like to try it with my favorite 160 grain bullets to see how those work from a .38 Special case. I will need to figure out what bullet to use with the .357 Magnum case since the crimp grove makes things tricky. If I do though, the result is more velocity.

So far, it looks like a safe load of Triple Seven is around 25 grains by volume using a .38 Special case and around 30 gr in a .357 Magnum case. Both of these appear to be in compression but I will need to confirm with the correct bullets. Instead of the 105 grain cast bullets I have, I'm thinking about finding some generic 158 grain LSWC. 

The original load of 38 Special black powder was a 21.5 grains by volume of FFFg and a 158 grain bullet. So I've already got a hotter load. A 6 inch barrel revolver should get us somewhere around 950 fps. Finding reliable data for rifle data has been a little tricky. Someone had posted they tested a black powder load from a rifle that was around 1230 fps. I ran that number through a calculator and found that the velocity would be at 1000 fps at around 108 yards. With the correct lead alloy, I think we can make the short range work. I suspect that a soft lead alloy with a BHN around 5 to 6 would be around what we're looking for if we still want to be able to have expanding hollow points from my Lyman mold at distances under 100 yards. This will be a very short range setup.

A 357 Magnum case holds more powder, so I figure I can add a few fps to that rifle data. What could really help is a new mold that has a crimp groove setup for 357 Magnum instead of 38 Special but I can work on that later. I have a few of the 160 grain bullets from GT Bullets that I found in a box, I figure I can load up a few 38 Special cases and try to get velocity data from the Marlin 1894 CST.

Update: I loaded a few 160 grain cast HP bullets over 23 grains by volume into .38 Special cases for testing. I could only make 5 since I only have enough bullets to make that work but from my rifle with 23 grains by volume, I got 1245 FPS from my 1894 with a 16 inch barrel over my chronograph. I don't think I did a good job making them and would like to try again. 

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