Soon to be loading 357. I have some Magnus 158gr JSP bullets and using H110 powder. What are some of your min/max loads? All my books vary a lot!

Check hodgdon website. Don't recall exactly but I worked up to just under max with no issues in my Blackhawk. Use mag primers.

Stay with the load recommended by the manufacturer of the bullet to be safe.  One can err on the side of caution with .357 using the lower suggested or mid range loads,  better than one can max out the load working close to the max load, because they shoot .38 also. So a powder charge heavier than 38 is going to work with no issue.  With .357 the load will vary widely depending on the type of bullet. A lead semi wadcutter is cheap to load but wont stand the hot load that a jacketed hollowpoint will.  I've always used Unique and 2400 for .357 and powder should be based on the length of the barrel with a long barrel 2400 is a great powder.  I don't like powders faster than Unique for it because the light weight of the powder charge.  Be careful not to double charge them.  Also note load may need to vary by type of pistol for example the K frame S&W 6 shooters have the cylinder stop cut above the chamber that is where a hot load will blow them out and why they made L frame. N frame and Rugers seem to do fine with the heavy loads.  J frame S&W five shot the cylinder stop is between chambers like it is with the 7 shot L frame guns.

Thanks everyone. I should have mentioned in the original post that right now I'll be shooting these out of a Henry carbine.

I don't have my reloading manual at my apartment with me or my notes, I really need to bring it with me just to have something to read. I do recall that the Lyman 50th manual only has like a one grain difference between the min/max charges for H110/296. Like I said, I don't have my notes in front of me, but I think the min charges were in the 16 grains and the max 17. Somebody with the manual handy could probably correctly me.

The last time I reloaded I was using 140 and 158 XTPs with H110 and 2400, and I still have a good bit of experimentation to do. I haven't tried any lead or plated bullets with those powders yet, just XTPs. I do remember that when I was trying out H110 out of my Dan Wesson 15-2, I had specks of unburnt powder left over in the cylinder and I didn't get that with 2400. I was using minimum charges and didn't go up but maybe .2 grains or so since I didn't have a lot of bullets left so I didn't get to go near the max charges.

H110/W296 is the one trick pony of the powder world. It is a "go-fast" powder and that's it.
Most loads have a very narrow working range. Particularly with H110, don't go below the minimum charge weight. You will experience crappy ignition, high SD, and a very dirty burn.

The Hogden site lists 15.0 - 16.7 as the charge range for .357 with a 158gr jacketed bullet.
That should yield you somewhere in the range of 1600-1750 fps.

Use a magnum primer and as stated, a firm crimp.

My old Speer manual (11, I think) was what I used when started loading .357.  I was loading 125 gn JHPs and the max load in the manual barely fit in the case.

When trying a different powder I always use the manuf. data. They made it, they should know the most about it.

If data is ''all over the place'' as you state, then I start at the lowest I see data for and work up from there.

My experience with H-110 is that it's a full power load only powder and there's not much room to work with, so I stopped using it and went to 2400. I like it much better.

I load for a rossi 16" carbine. I worked up from hodgdon min to max with no issues.

I dont have load data with me, but I believe I settled at almost max for the 158g JHP I loaded.

Velocity out of the 16" was fast. Dont have the numbers. I know the 125g load hit almost 2200 fps. I think 158 was in the neighborhood of 1800fps.

Once you get to the top, you run out of case capacity.  My oal started to vary due to powder pushing up on the bullet.

Out of a revolver or rifle? If revolver, how do you get velocity that high? I know hodgdon says upwards of 1600 fps, but out of my 6.5" Blackhawk the highest I've seen was a bit over 1300 fps and as I pushed toward max I actually saw velocity decline slightly. I assumed I was just throwing burning powder out the muzzle at that point.

I've never had to roll crimp before. How do I know if I got a good enough roll crimp?

One way is to check for bullet setback. Sounds like you are shooting in a lever gun with tubular magazine. Load up and shoot all but the last one or two and see if you have any bullet setback (bullet is pushed into the case more). In a revolver it tends to be the opposite with bullets walking out due to recoil. Shoot 5 and check the 6th.

The other part of the equation is having enough crimp to get the right burn. H110 seems to do best when you have a heavy crimp. Maybe others can give some guidelines on how to measure that. I'm still trying to figure out what a heavy crimp is myself. My bullets don't walk, but sometimes I feel I don't have enough crimp and I wish I knew how to really gauge that.

as always work up carefully

357 158gr

current SIERRA book shows 17.3gr

speer 8 - 15.5

speer 10 - 17.8

speer 12 - 15.5

Lyman cast - 15.9

17.3gr got me 1269fps from a 6" 586  and 1748fps from a 16" rossi'92

older books showed hotter 2400 loads also

14.7gr - 1275fps (158swc)  5" 686

15.8gr 1364fps 158gr SWC  5" 686

H110 has been my "go-to" magnum powder since 1987, but I'm playing more with 2400 now, and liking it.

The Lyman manuals have .357 mag ( rifle) section.  Iirc