Question on a .357 Load in a GP100 with a 125gr bullet

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45flattop

Single-Sixer
Joined
May 8, 2005
Messages
392
Location
Jackson, MS USA
Someone I know, not ME, at my local gun club is using a load of
2400 behind a 125gr jacketed bullet with a standard primer of
17.5 grains of 2400, I looked that up and every reloading manual
I have(11 of them) show a top end safe pressure level with a lot
to a little less powder in this loading. Anyone have any further
information? When this fellow touched that load off it hurt MY
ears through my hearing protection muffs. I suggested that he
dial it back some or get some Buffalo Bore loads if he wanted
something suitable for hunting in that grain bullet, he wants his
stepdaughter to use her GP100 for short range shots at whitetail,
she's an excellent and steady shooter so I'm less concerned about
the suitability of the cartridge for deer than the load itself, her GP100
has had a great trigger job and wears some Hamilton Bowen rear
sights and groups with more reasonable loadings, very well.
 

DGW1949

Hunter
Joined
Apr 10, 2005
Messages
3,653
Location
Texas
My Speer #9 Manual shows a max of 18.3 Grns of 2400 over a 125HP...with a #550 CCI Mag primer.
Test gun was a 6" Ruger Security Six...twist rate of 1-18 3/4".
That manual was printed 35 years ago. Some suff might have changed soince then....dunno.....I aint a hotrodder, so I don't keep up with current trends on hot 357's.

Try some ear plugs under the muffs.
And keep an extinguisher handy, in case he sets the grass (or his clothes) on fire.

Hope this helped.

DGW
 

45flattop

Single-Sixer
Joined
May 8, 2005
Messages
392
Location
Jackson, MS USA
DGW1949":1dxsxypc said:
My Speer #9 Manual shows a max of 18.3 Grns of 2400 over a 125HP...with a #550 CCI Mag primer.
Test gun was a 6" Ruger Security Six...twist rate of 1-18 3/4".
That manual was printed 35 years ago. Some suff might have changed soince then....dunno.....I aint a hotrodder, so I don't keep up with current trends on hot 357's.

Try some ear plugs under the muffs.
And keep an extinguisher handy, in case he sets the grass (or his clothes) on fire.

Hope this helped.

DGW

Thanks, it did, I believe that Alliant 2400 as opposed to the originial
Hercules formulation has been revised downward in maximum
recommended loadings, I know that Elmer Keith's favorite old
load for the .44 Magnum under his bullet weighing around 240-250
grains was 24 grains back in the 1960s-1970s and that load is now
around 21.5 grains of the newer 2400.
 

fjlee

Bearcat
Joined
Feb 2, 2007
Messages
21
Location
Denver CO
My Speer #8 & #10 manuals for .357 Mag shows max load of 2400 to be 19.5 with 125 gr JHP. Starting load listed as 17.5 gr.

Sierra manual from 1978 shows max of 19.0 gr. of 2400.

Fjlee in Denver
 

Sharp Shooter

Single-Sixer
Joined
Nov 24, 2005
Messages
110
Location
MCCammon,Idaho,USA
My latest Speer Manuals (#13 and #14) both list a maximum charge of 17.5 grains of 2400 with a standard primer behind a 125 grain bullet. So according to them, the guy's right at maximum, but he's not exceeding it. I doubt he's going to blow up that GP 100 with that load. Whether or not he can hit anything with it is a different matter.
 

Steve C

Bearcat
Joined
Oct 8, 2005
Messages
14
Location
Phoenix, AZ, USA
The guys load is relatively warm but if worked up isn't out of line with much of the data old and new.

.357 mag using 125gr jacketed bullets with 2400 powder the Speer 13 says 17.5gr max as does the current Alliant donwloaded manual (no surprise). Speer 11 says 19.5grs, Speer 9 says 18.3grs. Alliant 2000 edition says 17.6 grs. Sierra circa 1973 and 1993 both say 19.0grs max. 1973 Hornady says 14.7grs max.
 

Ruber

Single-Sixer
Joined
Sep 24, 2008
Messages
432
Location
San Diego, CA
I've used similar loads in Blackhawks, GP100 and Taurus Trackers. You didn't mention the barrel length which really makes a difference with this load in my experience. In the old 6.5" Blackhawks, this load is fairly mild recoiling and can be very accurate. But in the Trackers and short barreled GP100s, it will produce more muzzle blast than top end .44 mags from my SBH. I was getting good results from a 4" GP but anything shorter was giving me some incomplete combustion and variable velocities.

Speer 13 has a discussion on magnum vs standard primers with the 2400 loads saying they got "improved" performance by switching from magnum to standard primers and worked up their new current loads. Like Sharp Shooter mentioned, that load is right out of the newer Speer manuals.
 

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