Thread: 357 mag subsonic reloading data

Originally Posted by Muddyundy

I hear you @Micky Duck.
I have tried to find Trailboss but can’t find any locally and no-one freights powder.
I can’t help but thinking I’m missing something with the AP70n that might make the load more consistent.

I shoot a lot of cast in a Rossi Puma 92, but not subsonic,.well, not deliberately. When I got it I had a small bunch of 38 sp Pistol loads that had been given to me that I decided to shoot off rather than deconstruct. There was a variety including wadcutters with what turned out to be very small amounts of powder behind them. I finished up knocking several projectiles out of my barrel with a rod. Fortunately I was watching for problems. So first thing, whatever low load you use, have a rod on hand and make sure the bullet actually left the muzzle.

Second. I developed a bunch of goat loads using both 357 and 38sp data. I used AP70N to good effect in both. But I was going for max hitting power not subs. I was loading 38sp cases to strong +P levels which occasionally in older multi fired brass gave me split cases. But they were deadly and accurate and pre-Aunty I did so to get more rounds in the tube. I have used other shotgun/Pistol powders and found they all worked. I think you could persist with AP70N and do a finer increment test of .2gn steps downwards. I suggest a Balance Beam measure as .2gn is about the margin of error on most sub $125 digital scales. Your Balance Beam will be precise. 296 is a great powder but not for reduced loads.and I don't see it published for 38sp Do not go below stated minimum with this powder. It truly is a minimum as Micky warns. It is a 357mag load not for 38sp. Titegroup is a very fine precision powder and will produce 920fps with 3.8gn under a 158gn projectile in 38sp. Folk are wary of it because it is not bulky and is real easy to double or even triple charge cases..not fun at all. But you should find this a very accurate powder. Was loved by paper punchers with Wadcutters for its accuracy.

Finally I would be wary of putting 38sp loads into 357mag cases. The different case volume will give you different pressure performance and it may not always be to your liking. There are plenty of powders and published loads specifically for 357mag that are subsonic. I shoot them in 357mag Pistol and if I want to shoot 38sp loads in the Pistol I use 38sp brass, not 357mag - there is no need to mix them up. Good luck!