Just bought a 6” GP-100 that I plan to primarily use for shooting critters.  I have some W296, virgin brass and a variety of quality jacketed bullets to load for this purpose.

However, I also have 500 or so plated 158 gr bullets I’d like to load in mixed headstamp .357 brass at a milder level appropriate for plated bullets.

The powders I have available are:

True Blue
W231
Bullseye
Titegroup
CFE-Pistol
Power Pistol
BE-86

Any recommendations on a good choice of powder?

3.4 grs of 231 under a 158gr cast bullet is an absolute joy to shoot out of my GP100.

I let my friends 13 year old daughter shoot it and she loved it.

I know it's not on your list of powders. 14gr of 2400 under a 158gr berrys plated is what I run. It's a nice warm accurate load. Out of all the powders I have tryed for 357mag 2400 is my favorite with h110 a close second. Bullseye and titegroop will turn out some very nice plinking loads too.

I was about to suggest Trail Boss but that W231 load is likely the cheapest 357 bunny fart load around.

I use Titegroup for my light loads as it doesn't take much.  True Blue is very similar to HS-6 and great for medium level loads.

Mid power .357's are best accomplished with about 6 grains of Unique. Book max is 8.

Nobel Sport Ba 9 is about the same if you can't find unique.

win231

amazing accuracy

5.5 to 5.8 grains of Titegroup always worked well for me with pretty much any jacketed or plated 158 gr. bullet.  It would (just) make major from a 6" barrel back when a 6 shot .357 could still be somewhat competitive in USPSA revolver class.

I just use a minimum charge of 15gr of 296 with 158gr coated lead bullets.

I used 4 grains with a plated bullet with similarly good results.

A “mild” load for .357 calls for “not magnum powders.”  As dryflash3 mentioned, True Blue is a good choice, as are several other of those listed.

As always, start with a starting load.  Those starting loads may be too mild for you, or they may not give you enough pressure to seal the case mouth (you get sooty cases this way), so definitely work up to a comfortable, manageable load.

My preferred .38 special “mild load” with 158 grain wadcutters is quite a bit hotter than those “bullseye mouse fart” loads folks loved back in the day.  But they fire clean, with good accuracy.  When I can start loading again, one of my projects is to morph those loads into .357 brass.  It is not as simple as “just put the same charge in the bigger case,” so I’m going to be careful about this.

I really like Bullseye for a very accurate but mild load in 38. I would try the lowest published weight for it in your manual.

The suggested 231 load should be really nice as well.

8.1 gr be-86 under a 158gr hardcast bullet for 1150 from my 2.75 and 4" guns

I guess it depends on what you mean by milder.  In .38 SPL the personal interpretation could vary on that from the mentioned bunny fart to standard .38 loads most would consider mid range below the full house +P stuff.

Bunny farts are generally at or even below manual minimums ....definitely down in the Bullseye W231, True Blue range.  The mid range and magnum burners are just not suitable there.   I would stay with the fast burners until about 3/4 of the recommended velocity range in the reloading manuals.  Once you start approaching the max loads for the fast burning powders I would begin looking at the mid burners.  BE86 would be where I pick up ther but  edit, Power Pistol would likely do it the same.

I personally think one is better off using a faster burner up toward it’s top end than using a a slower powder in the slower powder’s usable end.  The slow stuff just gets so dirty an inefficient there.  I also do not like running at any powders absolute max.  I want my own safety margin on top of the ballistic labs for whatever might crop up, bad powder throw from static cling, a flawed case, a set back bullet. etc.

Then I start looking at the other less important factors,  how clean is it really doing for me.  am I getting debris under the ejector when I do a quick reload?  Is the gun nasty and hard to clean or does it just look ugly and wipes right off?  I can live with the latter if I don’t get the debris in the ejector.

Any pressure signs?  That’s a full grain over max with a 158 gr cast RNFP per Alliant’s guide.

I just loaded a batch at 7.7, 7.9 and 8.1, but haven’t shot them yet. They are mainly for an Uberti replica 1873 carbine.

I wouldn't get within a mile of full power loads in an 1873.  It's a fairly weak action unlike the 1892.

That said, for the OP, I've been shooting 5.0 gr. Bullseye under a 158 gr. bullet for just over 40 years as my go to load.  Right around 1000 fps in my guns.  Way less than max. and pretty darn accurate.

Im sorry, 8.1.

They're a great gp load @ 1150fps. Which is what I get from the AE 158gr jsp

Good point.  To me, a “mild” load would be about the equivalent of a .38+P but loaded in a .357 case.

I appreciate all the responses.  

W231, Power Pistol and Bullseye sound like good options to try, as I have plenty of each.  I’ll be loading soon as I picked this up from my LGS today

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Yea you could do the mid range burning stuff up there with little issue.  You should have the pressure and heat for a good efficient burn.  

Try a couple powders, one fast and one mid range burning,   see which you like.  I expect a difference in grime and  felt recoil impulse between the two.

Then just choose which you like since it sounds like you are in the overlapped area for the burn rates.  

Then factor in other reloader ideas, like powder consolidation so you don’t have 87 varieties on the shelf to stock.   It happens so fast. .  Some guys like flame and flash.....I like retardant.  


i have a gammut on the shelf

W231, clays, universal clays, A5, BE86, sport pistol, cfe pistol, WST. H110, Unique, 2400.  and likely others I forget.  I would like to consolidate more and likely will but some stuff just works.   I am creeping toward a shift to more modern formulations.  Bullseye is off my shelf but I would use it if that is all I could find.  W231 is a harder one to let go of.   It has been a reliable product for me.  These days being choosy isn’t that much of an option anyhow but trying what you can obtain does generate experiments and wider experience.  For many of us that is a nice part of it, others just want to produce ammo for their main purpose.....shooting, with less concern other than they have good ammo.  It is all ok.


Thinking on it a moment more.....yea I probably would use the faster powder on hand for the plated bullets.   Save your other powder for magnum and firmer loads.   Then again, look at old bottles I like to move on from and want them used up. Perfect pairing for that box of 500 plated bullets if you aren’t going to keep buying them.  I didn’t see where you said that you wouldn’t restock them specifically though, just a perception.

I use Clays for mild 38 special loads and it works extremely well. Very clean and very accurate. 2.9g is what I use for 158 grain lead bullet.

Hodgdon shows Clays loads for .357 mag data with 3.2g as starting with a 158 cast

Bullseye and Unique are my 2 main "go to" powders for light loads. I have found in small cases such as 9mm and 38spl I can produce identical loads with either but with Bullseye that load is typically a grain or so less.

Depending on what velocity you want to achieve I may be inclined to use Unique in the .357 case just because it will take up a little more space.

Motor

As DryFlash suggested, True Blue is good for soft .357 magnum loads.
I run GP100 4" and 6", awesome revolvers.
Do you have objections to shooting 38 Special cases?
After a morning of full power 357 mag loads, running mild 38 Special, again using True Blue and/or CFE Pistol, mild 38 Special is a joy to fire.

Another nice thing with .38 special cases,.....in some of the smaller frames and grip combos a speedloader reload is an easier task if you are playing around.

I avoided .38s in my .357 chambers for years to avid the crud ring warnings.  I found an extra set of used Dillon .38/357 dies in a gunshop and set them up to run .38s and leave my other set for .357.  

I got over the crud ring drama. I clean my guns anyhow.

I’m going to stay with .357 cases only in this revolver.   I have a smaller, snub nose .357 that almost always sees .38 Spl loads, but I’ll save the .38 brass for use in it.

I understand the speed losder aspect, but speed loaders wint. E used as this gun really isn’t going to see combat reloads

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Trail boss.  I developed a "long load 38 spec" that is the length of a 357 cartridge using a long bullet.  Purpose was better feeding in a ruger 77 357 using a suppressor and utilizing 38 spec brass.  158 grain berry/xtreme bullet.  Lowest grain estimation resulted in squibs half way thru a 16 inch barrel.  Midrange worked out and got something that worked.  Out of a revolver they was hardly any recoil.  GP 100

@Derek45

I don’t know if this is amazing, but W231 under a plated 158 gr HP performed nicely at 60 yards today.

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nice

Titegroup or HP38/W231 always worked for me.

Cant remember charge weights, been a few years.