Load data tables differences i.e. +50% !!!!

[kenlee]

.357 magnum for a Ruger M77.

158 grain hard cast bullet using HS6 powder and magnum primer.

The Hodgson reloading centre for a 357mag rifle via the web gives:
6 grain (1083 fps 12900 cup) to 7 grain (1224fpf 15500 cup) for a 158grn LSWC via an 18" barrel.

Now, the Lyman Load Data booklet for revolver Calibers - printed Oct 2011 gives:
9.2 grain (1150 fps 35700 cup) to 10.2 grain (1253 fps 42700 cup) for a 158 grn Linotype cast SWC via a 4" barrel.

Both specify a magnum primer.
I know the Lyman data is for pistol but why such a difference - look at the Hodgson pressures!
Also, the Hodgson data for pistol specifies the same loads and pressure but a slightly lower MV.

Hodgson may have been using soft swaged lead and dropped the load to avoid leading, but the speeds are not that much lower.
Lyman also warn against using less than the starting load which is greater than Hodgson's maximum load.

I have loaded and shot 6.2grains with 158grn hard cast SWC and Fed magnum primer. A mild load (did not chronograph - blame the wife) giving good groups at 20 yards; smoky, very sooty cases and no leading.

I'm open to ideas on this one.

[EagerNoSkill]

http://guns.wikia.com/wiki/.357_Magnum
"Much credit for the .357's development is given to hunter and experimenter Elmer Keith. Keith's work in loading the .38 Special to increasingly higher pressure levels was made possible by the availability of heavy, target shooting-oriented revolvers like the Smith & Wesson 38/44 "Heavy Duty" and "Outdoorsman", .38-caliber revolvers built on .44-caliber frames. While the .38 Special cartridge is limited to 16,500 c.u.p. (copper units of pressure), the .357 Magnum is loaded to 35,000 c.u.p. The objective was to create a handgun cartridge that combined deep penetration, flat trajectory, and long range."


The 357 is designed for 35,000 c.u.p. so the second you quote is past the max c.u.p pressure but could/should be safe in a good gun!
The second load is closer to true 357 levels!

What the first load is really a .38 Special load (despite the labelling) and may be to replicate .38 recoil levels or be a soft load for 357's.

[dromia]

There will be no leading issues due to velocity at those levels.

[Sim G]

The first load is Cowboy Action Data. Light recoiling for sport use. The second load is a "proper" .357 load. Expect 10-15% more velocity out of a rifle with the same load.