IMR PB & .38 Special 125-gr plated problems

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IMR PB & .38 Special 125-gr plated problems

Postby Morne » Mon Jan 02, 2017 7:53 pm

Since it was so miserably overcast/misty/foggy today I decided to do some chrono work.

I got some free 125-gr X-Treme CPHPs for .38/.357 awhile back and have been trying to work up a viable and SPEEDY load. HS-6 worked OK but not great. I have a partial jar of IMR PB laying around, though, so figured I'd give it a shot. There's plenty of reference (jacketed) data for everything from soft .38 Specials (3.6-4.1 grains) to moderate .357 Magnum loads (4.5-5.9 grains). Thus, I built a ladder of 3.7, 3.9 & 4.0 grains in .38 Special casings and 4.5, 4.8, 5.1, 5.4 & 5.7 grains in .357 Magnum casings. All were primed with CCI-500 SPP.

Meteorological Data:
44 F, 91% RH, 30.15" Hg

The .38 Special loads barely left the barrel they were so soft. I was so concerned that I checked the barrel for obstructions after each shot. Finally got one bullet from each across the chrono, but I think they stopped for a cigarette halfway there first.

Taurus 66 with 6" barrel:
3.7-gr = 416 FPS
3.9-gr = 424 FPS
4.0-gr = 411 FPS

Needless to say I was aghast. I put the remaining rounds aside to be disassembled. Next I ran the .357 Magnums to not much better effect.

Taurus 66 with 6" barrel:
4.5-gr = 411 FPS
4.8-gr = 643 FPS
5.1-gr = 699 FPS
5.4-gr = 770 FPS
5.7-gr = 797 FPS

This just sucks. Even the highest load for .357 Magnum barely yielded .38 Special velocity. The whole point to running 125-gr slugs was to play with higher speeds, something I've now failed at with two different powders.

Obviously, I could try magnum small pistol primers. That MIGHT help a little bit. Back when I played with HS-6 I used WSP(m) primers though, still not very impressive.

I have a go forward plan. I've got some Accurate #5 kicking around that I'll try next. Maybe try a W-231 load, too. But in the meantime I am wondering WHAT DID I DO WRONG with the IMR PB to get these horrendous results? Is it possible the powder has just gone bad (second owner, jar opened before I got it with a lot of other reloading stuff)? Have others found IMR PB load data to be on the atrociously low side?

I did some other chrono work today that gave believable results (all cowboy loads with lead or coated bullets) so I'm not suspecting that my chrono is bad. Santa failed to come through on the new chrono, though.
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Re: IMR PB & .38 Special 125-gr plated problems

Postby HancockCountyHAl » Tue Jan 03, 2017 10:46 pm

You need to put in some more powder. Hodgdon says 6.5 grains of HS6 is the starting load for .38 special.

125 GR. HDY XTP
Manufacturer
Hodgdon
Powder
HS-6
Bullet Diameter
.357"
C.O.L.
1.455"
Starting Load Grains 6.5
Velocity (ft/s)
931
Pressure
13,100 CUP

http://www.hodgdonreloading.com/data/pistol
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Re: IMR PB & .38 Special 125-gr plated problems

Postby Morne » Tue Jan 03, 2017 10:55 pm

You're confusing powders. While I previously tried HS6 in .357 Mag with this bullet (in loads exactly as shown on the Hodgdon site, through not getting anywhere close to the velocity) the powder charges reported in this thread are for IMR PB.

The linked Hodgdon data agrees with what I loaded (and gave awful slow results).
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Re: IMR PB & .38 Special 125-gr plated problems

Postby HancockCountyHAl » Tue Jan 03, 2017 11:30 pm

Morne wrote:You're confusing powders.


Dazed and confused. Sorry, you're right. How's your crimp and your scale accuracy?
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Re: IMR PB & .38 Special 125-gr plated problems

Postby Morne » Wed Jan 04, 2017 9:33 am

HancockCountyHAl wrote:How's your crimp and your scale accuracy?

My scale accuracy isn't anything to brag about. That said, I disassembled the ones I didn't shoot and weighed the powder that came out of them. Got just what I was expecting.

I crimp a full turn in on the Lee FCD. Took several good whacks with the impact bullet puller to get them undone which I take as a good sign.
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Re: IMR PB & .38 Special 125-gr plated problems

Postby slwroln » Sun Jan 08, 2017 9:32 pm

I use IMR PB for my 357. I load Extreme 158 gr SWC. I found and old IMR load publication on the internet. I tried the data from Hogdon and I was having the same problem your having. I don't have a crono but I would say they are 38 +p in 357 cases with a 158 gr swc
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