Best powder for 3" barrel S&W 686 .357

[Walkalong]

While the slow powders will have more muzzle flash than the fast ones, all of them are consumed, what you see isn't powder burning. Some powders have flash suppressants as well, while some don't. Pick a medium speed powder and work up a nice .38 Spl +P load with it. Power Pistol is a flashy powder. Not a good choice for what you want to do.

 

[vaalpens]

I'm not sure if you are looking for a 38spl +P load or a 357mag load using Power Pistol. I will list a few loads I have tested, but please note that thses were tested out of a Ruger SP101 with a 3" barrel. This should give you some idea so that you can work up your loads to the velocity you are looking for. I don't know what the pressure is on the loads listed below, but just to be safe, one final note:

CAUTION: The following post includes loading data beyond currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The High Road, nor the staff of THR assume any liability for any damage or injury resulting from use of this information.

Ruger SP101 3"
357mag
COL: 1.620"
ACME, 158gr, SWCNLG, Longshot, 8gr, SBPRSP
Average: 1055
ES: 20
SD: 8.5
Force: 390
PF: 166
Velocities: 1049, 1065, 1062, 1054, 1045

Ruger SP101 3"
357mag
COL: 1.620"
ACME, 158gr, SWCNLG, PowerPistol, 6.9gr, WSP
Average: 965
ES: 29
SD: 11.2
Force: 327
PF: 152
Velocities: 970, 971, 947, 976, 964

Ruger SP101 3"
38spl
COL: 1.475"
ACME, 158gr, SWCNLG, PowerPistol, 5.7gr, WSP
Average: 921
ES: 24
SD: 9.4
Force: 298
PF: 145
Velocities: 926, 915, 924, 909, 933

I hope this will give you some indication of what to expect using Longshot and PowerPistol.

Be safe.

 

[Reeferman]

To me, it just doesn't get any better than 12gr of 2400 behind a 158gr bullet out of my snub model 19. An under max load, very accurate and still lets you know you're shooting a magnum.

Is that Alliant 2400?

 

[forestswin]

I shoot Power Pistol in 9mm
its very flashy
from what I read - its one of the most flashy powders
if you wanted flash - one of the things would be to use a very light crimp
maybe a tighter / heavier crimp might reduce flash

what powders do you have?
Bullseye is not so flashy

 

[jski]

What powders do I have? TiteGroup, H110, Unique.

I'm also looking at Accurate #5. Perhaps not so flashy. And perhaps fast enough to do well with a 3" barrel.

 

[ArchAngelCD]

What powders do I have? TiteGroup, H110, Unique.

I'm also looking at Accurate #5. Perhaps not so flashy. And perhaps fast enough to do well with a 3" barrel.

Again, you are focusing too much on the 3" barrel. I give up!

 

[Walkalong]

Yep, you really need to forget about the barrel length and powder speed correlation.

Unique will do exactly what you want. AA #5 is also a great choice. Both are versatile and can be used for other things as well. Sounds like you are all set. Pick out a .38 Spl +P load with Unique out of your load book, work it up, and have at it.

 

[stoky]

Does the "new" Unique have a flash suppressant?
Of the three powders you have, I'd use the TiteGroop for cast bullets, the H110 for stout jacketed loads. Unique would work for either though.
You're good to go. A 3" .357 is gonna have some flash.

 

[cfullgraf]

What powders do I have? TiteGroup, H110, Unique.

I'm also looking at Accurate #5. Perhaps not so flashy. And perhaps fast enough to do well with a 3" barrel.

Here's a suggestion. Get a chronograph, some good ones can be had for less than $100. Work up loads to maximum pressure limits with each powder. Remember to stay within the maximum, safe charge recommendations by reputable load data sources.

Chronograph them in your 3" barreled gun, and let us know your results. Inquiring folks want to know.

 

[stoky]

Heavy bullets and fast powders are the recipe for low flash.
It's a dangerous combination for hot roding
Picking a powder with a flash suppressant helps.
Cast bullets often make less flash than jacketed, but in low/no light, they can make a lot of smoke (from the lube), and make follow up shots difficult