Hi
Will be loading 357 mag for a GP100 using hornady 125's and 158 XTP's. Would like some advice on "lighter loads" for 2400 and target practice with that powder and those bullets... easy to "load up"...lots of data on full-power, but not much on light loads.
Advice from anyone on experience with these components?
Thanks.

Why not switch to one of the faster burning powders like W231, Unique, Universal Clays. You can get more bang for the buck ( no. of reloads per pound), work up easy shooting accurate ammo. Try about 4.5 gr of either.
If you want to stick with the 2400, just go with the 125gr bullets, and about 13 gr of 2400.
The slow burning powders don't lend themselves to reduce loads very well.

What saddlesore said. The 13 grain load is a decent one.

I like 2400, but for less than full throttle loads I go with HS-6 or Blue Dot.

Do not use 2400 for reduced loads; it is at it's best in full throttle loads (I've loaded in several cartridges for 35 years). For lighter loads, go to a faster powder as others have suggested...Unique is a good place to start.

TRY blue dot ITS WHAT IVE USED FOR YEARS IN MID TO UPPER MID VELOCITY 44 AND 357 MAG LOADS

http://www.handloads.com/loaddata/d...ype=Handgun&Order=Powder&Source=

You should be able find all you need right there.

If cost is a factor, it doesn't make sense to use slow powders for lighter loads. The price is the same, but you'll need to use two to three times more of the slow powder even in lighter loads. I like Unique all around, but 231 works very well too.

2400 is a lousy powder for light loads.

I was given a large amount of Bullseye and it became my "go to" light load powder. My 4" S&W 66 shoots very well with both 125's and 158's loaded in front of Bullseye.

Speaking of lighter loads, particularly with lighter bullets, I was surprised to see how close the velocity was and very surprised by the reduction in recoil/muzzle blast of Ramshot's ZIP when used in the .357 Magnum vs. 2400 and the other slow burning powders.
The other thing is that if you zero the gun with heavy loads and try shooting much lighter ones, especially if you go from 158 gr. bullets to the 125 gr. ones, the gun rarely shoots them any where near the same zero. E

Yep, lighter bullets usually shoot a lot lower.Less muzzle flip.

The Trailboss powder that a lot of Cowboy Action Shooters will give a full case, and yet will be a light recoil load

My standard 158gr practice and plinkin load is 6.7grs of Unique. I use this with cast, plated and jacketed bullets. It's above .38sp yet below published .357 loads. As stated 2400 is a poor choice and I wouldn't recommend BlueDot for light loads either. It's still a fairly slow powder when it comes to handguns.

Another one to try is TiteGroup. About the same burn rate at Bullseye (i.e. fast). Note: I don't like either of these fast powders for cast lead when you are anywhere near max for published loads. They seem to burn too hot melting the base of the bullet. Results in leading. Stay at the bottom of published loads for best results using cast IMO.

Yeah, heavier bullets typically shoot higher than light ones because they generate more recoil.

Among its various uses Unique is almost perfect for mid power .357 loads. Old, but it has been around for a long time for a reason.

As others have said 2400 is a good warm load powder.Unique is a great medium to light load powder,blue dot will work,As will 231.

How about accurate #5 or 7.

I agree with Kevin. 2400 is nasty too. I love it for full house loads.

As everyone has noted, 2400 is not the best powder for "light" loads but the nice thing about 2400 is that you can load it down to about 80% of max and it still maintains good accuracy. I've proved this to my satisfaction in the .357, .44 Mag and .45 Colt.

You didn't say what barrel length your GP-100 is but I was looking over my old targets and see that 12.0 2400 under a Hornady 158 FP-XTP got 1076 fps from a 4" GP with good accuracy. 12.5 grains with that same bullet from a 6" GP-100 also gave good accuracy but I don't have a velocity reading on that one. A SWAG would put it a bit over 1100 fps from the longer barrel. "Good" accuracy means 1 1/2 to 2" 10 shot groups at 25 yards.

Going below 12.0 grains 2400 starts to burn erratically and begins stringing vertically. I'm using CCI-500 primers in all of these loads, btw.

If you really want to use 2400 with your 158 grain XTP's and have some .38 brass, 10.0 grains in .38 Special cases gives terrific accuracy. Velocity runs just under 1000 fps in 4" barrels. I stumbled on this one trying to get a safe powerful load in my Smith Model 15 .38 and it works great in the 4" GP-100 as well. Wouldn't recommend it as a steady diet in the K frame Smith but it's a creampuff in the bigger Ruger. The smaller case capacity keeps the pressure up a bit more so it burns well while the reduced charge weight still keeps the velocity and recoil down. It's such a great load in every .38 and .357 I've tried it in it might be worth your while to get a bag of 100 .38 cases.

Sorry I don't have anything for 125 grain bullets but I've never worked with those much.

I think 2400 is very dirty.

Thanks for all the great advice and info.