down-loading 357 to 38spc velocy

I am thinking, I am going to move away from 38spc brass entirely. I only use it in revolvers and they are all 357. I also have 357 rifles and I like commonality.

I think I will load for full power 357, I can run them in anything. And ‘down-load’ for comps and plinking, to get close to 38spc in terms of handling.

I pretty much exclusively use, 158gr projectiles, if that helps.

For shits and giggles I have measured my 357 loads from 6" barrel at a respectable 1200fps average (one outlier at 1132fps, rest 1200+). :slight_smile: Ka-fn-boom! Obviously uncontrollable in rapid fire.

Question for revolver shooters, what velocities (preferably with heavier pills, 158gr perhaps) are you aiming for? Specifically for comps, like service matches and WA1500. Usually I just work up to something that’s accurate enough and feels good enough, but I never measured 38spc. Definitely not after anything amebic (like Western Action) that I can’t feel.

Thoughts, suggestions, advice?

Ok these are my opinions only, normally if the match requires a specific power factor, eg 120PF, I would be aiming for a load around 125-130PF, just to give a safety margin if chrongraphed during a big match. Normally I like a lighter projectile with more felt recoil and less muzzle lift rather than a heavy projectile with more muzzle lift and less felt recoil, personal preference will dictate and speed of shooting required. There is a couple of problems with longer 357 length cases. Firstly if the match requires speedloading, then the shorter the case, generally the faster it will be to reload. The other problem is that a 357 length case burns powder inefficiently, generally the smaller the boiler room in the case, the better it will burn the powder, less airspace equals more efficient burn which should equal better ballistics, of course there are a few variables to this.

Thanks, @Cavallino. Regarding projectile weight, I use them across all 357 firearms, so preference is to stay on the same projectile. However, I was thinking about wasted space, actually. That was my main drawback, because that’s a lot of space. PF - not a concern (with revolvers), just club comps, nothing serious enough to warrant it.

Main concern is definitely wasted space which I suspect would also translate to noticeable SD, even with accurate measurement.

I might play around and see what I come up with, but it’s starting to look like a bad idea.

I’m running 4.5 grains of Unique behind a 158gr cast bullet in a 6" barreled 686 for my 13 year old son.
It is accurate and doesn’t have too much recoil, we shoot a 25m service match which he does well in.
Certainly not a pathetic “pop-gun” load like those used in Wanker Action.


I run 5.5gr of AP-70N behind a 158gr LRN projectile out of my .357 rifle for Gallery Rifle events, and the same load as a general shooting load for my club’s centrefire matches, and been really happy with it.

Never had the chance to chrono it, but there’s no muzzle flash and it has very mild recoil too - and none at all out of the rifle.

1 Like

The other thing you can do is play with powders, Unique as Danmac mentioned would be a good starting point as well as Trailboss which was designed to get around the airspace problem.

1 Like

I use TB, but I have a feeling it’s not going to measure well in a thrower.

Unique, I don’t have, but I do have AP70N, so I will try that… Although ADI hasn’t released the equivalent, so that could be a one off.

Trailboss actually isn’t too bad from a Lee thrower for me - it’s just messy so I always need to brush up the reloading bench when I’m finished with it.

I have an rcbs thrower that throws TB just fine also.

1 Like

I’ll have to test…

Yeah, I’ve found 4.5 grains of AP-70 works well also but due to it’s scarcity and lack of availability in the future I didn’t recommend it. ( I’m saving my stockpile for use in a different firearm.) I recently acquired a “few” canisters of Unique, it is an “equivalent” powder to AP-70, hence the load advice.
I can throw 4 grains of trailboss, AP-70 or Unique out of a Lee thrower no problems. Like anything else, it’s just a matter of consistency. You need to get a smooth rhythm going and maintain it. I find, when it comes to small charges, that I can get more consistency with my Lee thrower than with a Harrells, go figure.

1 Like

Cool, tanks, @danmac. Yeah, I am hoarding 70N for another gun too… And I have a Lee thrower. Anyhow, we shall see when the mass-home-detention of Melb is over.Will be testing in Dillon (using Dillon thrower), so who knows.

Also find TB throws fine. Not perfect but good enough for consistent loads. Obviously not handguns. Just use it in 223rem.

What bullet are you putting ontop of the TB in 223 Rem? Velocity??

I’d have to refer to load data or old posts but I use 50gn Zmax and from memory around 1800 or 2000fps. Turns the 223 into a beefed up 22WRM. Shoots well to 110m but starts dropping fast beyond that.

1 Like