Looks like Alliant lists a max charge of 14.8. I have never done this load before. What are your pet loads for 2400 with 158gr jacketed bullets?

13.0 grains of 2400, 158 grain JSP or JHP. I've used it for decades with complete satisfaction. Killed 2 whitetail does with it using a Marlin carbine. It averages 1658 fps from the Marlin, but I've never run it through a chronograph in a revolver.

I have loaded that charge with 158 gr. bullets, it is the “top of the heap” of 357 magnum loads. My everyday magnum load has been 13.5 gr. of 2400 over the same bullet. I have been shooting this load since the 70’s and it will do anything you want to do that the 357 is capable of. I have used the max load for hunting white tail deer, it has been a reliable deer harvester for me. The 13.5 load has put several deer in the freezer also.

Back in 5/9/2013 I tried some 2400 powder out in my new 686 6" revolver
with the Hodgdon 158 gr. XTP bullet with the same load as mentioned in post #1.

The first round fired took me by surprise, with a flyer from the recoil.
After getting a firm grip, the next four were inside the size of a golf ball at 15 yards, from a rest with iron sights.

The chrony said the loads averaged 1274fps.

I have had this bullet up to 1340fps with 2400 powder but they were not as accurate in this L frame.

All noted. Thank you very much for the advice and sharing your experience. Much appreciated!

...if I go over 15 grains of 2400 with a 158 gr. bullets. The gun should handle it, but all are different. I'm doing a little work now to decide what the upper limit is for my gun. I don't HAVE to shoot max loads, but I like to be able to when I want to.

__________________
"He was kinda funny lookin'"

I have found 14.5g of 2400 with a STANDARD PRIMER to be the most accurate in my 686. But it is unpleasant to shoot due to sharp recoil. I prefer to use 15.7g of H110. My Ruger GP100 does not need high verlocity to produce great accuracy, because it has a higher rate of twist than the 686. I believe the 686 would do better with lighter bullets, perhaps in the 140g range.

Back off 10% from the Alliant charge and work up from there.

I've chronyed 1100fps w/13.8 2400 behind a 158 grain JSP using a 4 inch 686.

I posted this a year or so back .My Marlin carbine uses this 100 yard load. My Bill Davis 681 likes 14 grains of 2400 with a 158 JHP. This is the target I worked up for the Marlin but too warm for a K frame. Just drop back on the powder. This is a good 357 load chart.

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Interesting, care to elaborate on the different twist rates?

With 150gr/160gr jacketed bullets I use a max load of 14.2gr of 2400. After testing several different jacketed bullets in 2 1/2", 4", 6", 8" & 10" bbl'd firearms over a chronograph. I found there was what's know as "diminished return" when going over 14.2gr of 2400. Diminished return is when you add more powder doing ladder tests and the velocities rise pretty good #'s as the load increases. When getting near the top end the ladder tests velocities don't increase much. At this point the pressure is still increasing while the velocities have taper off.

With cast/coated bullets I use the max book loads, typically 14.5gr/14.7gr for +/- 160gr bullets.

^^^ yep, 'diminished return'. Been loading 38/357 since the late 70s' using 2400 and SR4756. Velocities kept increasing to a max fps realm and then primers flatten and difficult case extraction with no increase of fps.
I've tested to 15.0 with 2400/158jhp and use 14.0 as my standard load. I don't hunt, just range use. A good heavy crimp is needed for 2400 for a good clean burn.

If I am loading just for shooting in the heavy frame guns, I will load 14.0. If just for the K-frames, I drop back to 13.0. Even 13.0 of 2400 is not much fun in a Model 19. I don't have chronograph information handy but if memory serves it's just a bit less than 1200 FPS in a 4-inch barrel. That's plenty of power in a lightweight gun, IMO. Yes, 2400 does reach a point of diminishing returns, in my experience.

I see the same tendency in .41 Magnum. Nothing much is gained beyond 19.0 grains - except increased pressure, I imagine. Haven't bothered to find the threshold with recent batches of 2400 in the .44 Magnum. I hardly ever load anything more than 19 grains in it, which is plenty for me when using my normal selection of 250 - 275 grain cast bullets.

I think one of the reasons for the diminishing returns is because 2400 doesn't work well if it is over loaded. Doesn't take kindly to being compressed. No less an authority than Elmer Keith(at a Remington seminar) told me that many many years ago. Another reloading writer also told me if compressed it becomes somewhat erratic. True?? I don't know but filling the case to the base of the bullet as max has always seemed good to me. I have used a lot of pounds(2400) over the years in many different rounds. It is a good powder. For some odd reason I have used untold pounds of Hercules/Alliant powders of the older varieties and they always worked pretty well. So I think if you reload 2400 just keep it from being compressed give it a good crimp so it burns well and you'll be good to go. Believe it or not I have even loaded it in 45 with lead 230s and it even works in them. But first and foremost it is a great almost necessary revolver powder

Sure. Standard 38/.357 caliber twist rates for the three major US manufacturers are...

S&W: One in 18"
Ruger: One in 16"
Colt: One in 14"

The current Python has a 1 in 14" twist rate as well. Years ago, shooters would often ask their gunsmith to obtain a Python barrel and install it on a S&W frame. The resulting combination was sometimes referred to as a "Smithon".

Thank you but that's not what I was asking about elaborating on. I was asking about this:
"My Ruger GP100 does not need high verlocity to produce great accuracy, because it has a higher rate of twist than the 686."

Last I knew 1 in 16 twists were lower than 1 in 18 3/8 twists????
Last I knew gp100's had the same 1 in 18 3/8 twists as the s&w's????

No real need to worry about the slower rifling twist in an S&W with jacketed bullets and virtually all cast bullets. It handles even 180 grain bullets well for me at moderate velocities. I also shoot at extended ranges with my S&Ws with excellent accuracy an no indication of bullet instability. I once even loaded RCBS cast 180 grain rifle bullets (long ogive compared to pistol 180 grain bullets) in 38 Special cases and shot them at 800 fps in a K Frame Model 65. The S&W twist stabilized them just fine at that velocity with good accuracy at 50 yards.

The only time that I've seen even a slight wobble or marginal key hole on targets with an S&W revolver was while shooting on my PD's shooting team. At 50 yards using the 148 grain HBWC (very long for weight and caliber), you could sometimes notice a very slightly out of round bullet strike on the target when scoring. The Colt's 1 in 14 twist always produced nice round holes as the faster twist stabilized the 148gr HBWC more fully at 50 yards. My scores with S&Ws never suffered though and accuracy was as good as with my Colt Python at the time. My custom PPC S&W revolver had a 1 in 14" twist, but only because its diet was exclusively 148 grain HBWC bullets for match shooting in the High Master class.

As you are probably aware, long bullets need a faster twist and lower velocities generally do better in a fast twist barrel. The bottom line: The standard S&W twist rate, while the slowest of the major manufacturers, is just fine for what we do with a revolver.

Oh, and as far as the original topic, I also like 2400 in my 357 loads, both in a rifle and for revolvers.

__________________
Keep your powder dry.

13.5 grains with a 158 grain XTP gives me the best accuracy and 1200 fps out of my 4" 686.

andy05 : you Ruger GP100 has same twist rate as a Smith , 1-18.75 " . Go to the Ruger website and checked the spec sheet . Regards, Paul