Which Manual to Use?

I have some 158gr Hornady XTP's (#35750) and a jug of Hodgdon H110.
6"' Ruger GP100 .357. And a 16.5" Marlin but we'll leave that alone for now.

Hornady load data
8" Python
Starting Load- 12.7gr 1000fps no pressure given
Max Load- 15.6gr 1250 fps no pressure

Hodgdon load data
10" barrel
Starting Load- 15.0gr 1418fps 28.6k
Max Load- 16.7gr 1591fps 40.7k

That seem like a large difference in powder load.

I also looked in a Lyman manual
4" barrel
Starting Load- 16.3gr 1178fps 31.7k
Max Load- 17.0gr 1309fps 38.4k

I wonder why Hornady would stop at 15.6 grains. The bullet is rated for up to 1400fps and the others are at least one full grain more.
Lyman starts near the Hodgdon Max.
Lyman has less pressure with more powder.

These numbers are all over the place and I know mine will be different than all three.

Looking at the numbers, I have an idea of where I should start and max (I think), but would like some input from more experienced loaders.

The books are Hodgdon 2021 and website, Hornady app and Lyman's 50th.

What is the COAL listed on each? Are they all the same? Are all resources using the exact same bullet or the same weight just another manufacturer?

Also different sources will use different components for the primers and brass. Test barrels are likely never the same.

When I come across stuff like this I pick the middle of them and go from there if everything else is the same.


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Lyman and Hornady 1.590, Hodgdon 1.580

All three sources state the same model and part number of bullet.

With the 158gr xtp I run 16.5gr of h110 with a 1.590col and it is a blast too shoot. Make sure to use a very firm roll crimp. 14gr of 2400 under a 158gr bullet is awesome too. From what I have found Hornady is SUPER conservative with all there loads across the board.

With 16.5 or 17gr of h110 you will get the attention of every one shooting near you especially if it is overcast. Another awesome load is a 140gr jhp over 17.5 or 18gr of h110.

I use:
.357 mag
16.6gr 158gr
20.7gr 125gr

It's what my lee disk throws and seems to work well. i shoot mostly coated lead with great results.

Those new manuals are conservatively lower, powder wise, than older ones. . I have a few older edition manuals, i picked up from garage sales. . Older load data is higher powder charge compared to todays data. Based (IMO) on lawyers, so it's more cautious then older manuals. between the

If i get out to the loading room today i'll see what the older manuals show. Which is usually another 1-3grs difference.

Also as mentioned, each mfg data is based on X firearm, primers, etc.

In the mid 90's 357mag loads were reduced from 43,500psi to 35,000psi a 25% reduction made by sammi at smith and wessons request. The older max loades were to hot for prolonged use even in the N frame from what I have read. The model 19 & 66 is where most of the problems were coming from with max loads.

Quote:

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Originally Posted by beast556

In the mid 90's 357mag loads were reduced from 43,500psi to 35,000psi a 25% reduction made by sammi at smith and wessons request. The older max loades were to hot for prolonged use even in the N frame from what I have read. The model 19 & 66 is where most of the problems were coming from with max loads.

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Interesting, wasn?t aware of this. Do you have a source for this?

I know they changed many specs from the old CUP to PSI, updating even the older cartridges to the newer specs.

Thought S&W just says that the guns susceptible to issues are for occasional 357 use much like the smaller framed ones.


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I think multiple factors going on with the pressure reduction over time. Switch from CUP to PSI as testing equipment changed and also the "lawyer factor" + real word issues with high use (police) k-frame's.

(Old data while sometimes useful may not always be a great idea, my old speer book lists H110 for 38 special, I tried it and like you would expect not great results)



With a gp100 and h110 though idk how worried I'd be, starting at the #s in this thread should be fine. Some older data boarders on compressed charge, I don't think you can cram enough in to cause issues.