OK I got all the stuff to start doing it. Thought I would start with some easy calibers. 38's and 357's.

I have a Hornady manual and been to Hodgdon reloading online.

My question is who to believe?

In Hornady's book: 125gr. Hornady XTP. Max load 19.9gr. of H110. 1500 FPS.

On Hodgdon's site: Starting load Hornady 125gr. XTP 21gr. of H110. 1881 FPS Max load 22gr. of H110 1966 FPS.

The only difference the Hornady load used Frontier brass and 10" test barrel and Hodgdon used win. brass and 8" barrel. Both used WSPM primers.

That's a huge difference between the 2.

I think I'll go with Hornady's info. I don't need my 357's running at almost 2000 FPS.!!

Brad

Rifle versus pistol data I would expect. 1500 fps for a 38 special is HOT. But you mentioned 357 mag too, which is about where I load my N-frame S&W at.

Both pistol data and 357's only. A 38 at 1500fps would be a little HOT! Gun is a Ruger GP 100

Start at 19 and work your way up watching for pressure signs and see what shoots best for you ... A chronograph does help during load development but its not a must have. It does however give you a good idea as to where you are at regarding your loads

Most of my reloading experience involves rifle, so keep that in mind...

The answer will depend a lot on which brass you're using...

Hodgdon usually always runs their tests loaded in Winchester brass. It's very "roomy" brass with some of the highest case capacity (depending on the cartridge) on the market... At least with rifle cases. I don't load much pistol but I would venture to guess it applies to Win pistol brass too.

Hornady brass tends to have a bit less internal capacity... And they are known for being conservative with their load data anyway.

If you are reloading Winchester pistol brass then you will probably find a good load before you hit MAX charge anyway. MAX charge simply means that is where they stopped testing due to indicated pressure... It is rarely the most accurate load.

A nice sensible load without all the extra fouling and muzzle flash is the way to go... And your brass will last longer.

Mike

Will be using Starline brass.

No idea how Starline pistol brass ranks in internal capacity... Go with Scuba's advice and work your way up carefully. Do you know what to look for as far as pressure?

Mike

I've read about it in the Hornady manual. It showed pics of what to look for.

If you have any doubts then pay attention to them.

Mike

H110 and w296 are the same powder. Both are not recommended to go below published starting loads.
If I remember correctly, they require magnum primers and a good crimp.
Your velocities will be lower than test barrels most likely. Load a few at the 19 grain mark and try them out - might not want to go any higher.

I think you switched the barrel lengths. The Hogdon online site shows a 10 inch barrel, probably an unvented universal receiver, my old Hornady book shows a Colt Python with an 8 inch barrel. The 10 inch barrel, especially if it was unvented, should show a significant increased velocity.
I would also use the Hornady data, the Hogdon data is probably safe but at the maximum pressures the 357 muzzle blast will curl your nose hairs. Use ear plugs and muffs, ask me how I know but you have to ask real loud and speak slowly.

your going to see a velocity difference in the 2 inches of test barrel

the Hornady 19.9 max vs the 22.0 max of Hodgson

H110 is a bit of a different powder most poweders you work up and low is OK

H110 you don't go lower than 80-90% case fill so don't go below Hornadys data they tent to be a bit conservative in their data staying on the low side of things
most powder you reduce by 10% with H110 it states right on the jug reduce by 3% from max

as an example my 308win load is 2 gr over Hornady's max and still under Hodgdons and Lee's max

further oddity is H110 and Win 296 are the same powder but Hornady's book has win296 a max of 20.3gr

hogdon lists bot at 21 and 22 for starting and max

miss prints happen
case capacity matters different brass can have a different capacity
try and find 2 sources for all your data that agree or at least overlap

the Lee book is a good resource also and if I could find mine right now I would look it up for you
but I have no idea if I lent to to someone or where I put it

97% of 22= 21.34
97% of 20.3=19.69
97% of 19.9= 19.3

so like scuba said try 19 it is in the right range and above the 17.4 starting load Hornady lists