Speer 135 grain "Short Barrel" for .357 Magnum

[ArchAngelCD]

People are often so obsessed with trying what is "new and interesting" that they forget tried and true...Unique is an oustanding "fast-middle" powder for the .357 from a snub length barrel...and Blue Dot is next up...both are bulky flake powders that fill volume at lower charge weights, Unique is the faster---somewhat faster than AA7. Blue Dot is very close to AA7 - a tad slower.
With such a short barrel I would not use 2400, nor H110...both are too slow.
Since you have 135 grain slugs on hand, start with the load data for the 140 grain...with pistol slugs the bearing surfaces are usually very similar and the difference between weights is a piddling - statistically insignificant 3.6%. Considering factory weight variance could easily cause one "stated" 140 grain bullet to weight 138, while another comes in at 142, 135 is close enough AND it's BELOW the 140 weight.

With your barrel length, and the volume of the .357 case, resultant speed is primarily a function of the burn rate within the case...you're relying on that 40K psi average working pressure to deliver the goods versus a .38 spl's 17K. I'd go with magnum primers for that reason...they'll cause a faster pressure rise.

All that may be true but it doesn't address the OP's original question of finding a real magnum load for a 12oz revolver that isn't a full blown magnum. I personally used a newer powder because that's what Speer recommended. (and with good reason I might add)

 

[scooter123]

While I am certain using 2400 will be safe I have to question how practical it will be. That is an awfully slow powder for a 135 grain bullet in a barrel this short and I suspect the muzzle flash and blast produced will be rather alarming. Of course if you actually used this load in self defense it would probably cause your assailant to run away in terror even with a total miss. Might even set his clothes on fire. Downside is if you aren't wearing hearing protection you may end up losing all of your hearing because it will probably be the loudest load you've ever fired.

BTW, I experimented with a 21.0 grain load of H110 under a 125 grain Hornady XTP and learned first hand the issues with a slow powder and light bullet. Out of the 4 inch barrel on my 620 it produced about 8 feet of flame downrange and was LOUDER than a 4 inch 500 Magnum.

I am now loading my 125 grain XTP's using a 10.3 grain load of Accurate # 5 and it produces a low flash 1200 fps. load that is relatively normal in volume for a 357 Magnum. Since you are using a somewhat heavier bullet I believe that a load using Accurate #7 should prove to be an excellent choice. Speer seems to agree because I find it listed with a starting charge of 11.1 grains and a max load of 12.1 grains. BTW, they also list AA #9 but since their testing was done using a 6 inch model 19 I'm inclined to believe that #9 is too slow for a 1 7/8 inch barrel. Finally you could also try a load using Accurate # 5 for a bit more moderate load with less muzzle flash than #7. The load range for # 5 is 9.1 grains at start and 10.2 grains maximum.

 

[TheTinMan]

You guys are great. It's really valuable to get all these different perspectives.

I promise that I will report back with chronograph reports. Just can't promise when.

 

[Erich]

Oddly, I loaded the 135-gr Speer short barrel GDHP over AA#7 and Power Pistol for the .357 for my 2" Rhino a few years back. Here's the data:

c.55 degrees F/30% humidity (gorgeous cloudless day) at the ABQ City Range (5950'>sea level)

.357 Magnum loadings:

AA#7 12.1 gr under 135-gr Speer short barrel GDHP:

First six: M 1012/ES 39.88/SD 17.66
Second six: M 1022/ES 69.85/SD 25.96

Power Pistol 9.6 gr under same bullet:

First six: M 1013/ES 37.42/SD 16.24
Second six: M 1025/ES 46.83/SD 16.03

Accuracy was about the same with both rounds, but the AA7 loads were WAY louder. Since their performance was about identical, I think that Power Pistol is the way I'm going to go here. Velocities were a bit lower than I'd expected, but totally within the range I was wanting - I think I'll be using these.

Check out some pix - first, the two loads benched, SA and taking my sweet time @ 10 yds:

Now, look at the AA7 loading offhand, DA and about one shot a second at the same distance:

Now, I've not chrono'd these from my 3" SP-101, but they're plenty more accurate from it. I figure they're doing probably 1050 fps from the thing (some day I'll check it), and I keep the PP variant in the long-barreled SP as one of the house guns that my wife likes to have accessible.

Hope this is of some interest. Funny those were the two powders you mentioned. I thought about 2400 (and some other things - SR 4756, anyone?) but felt decently happy enough with the PP loading that I didn't want to start throwing now-hard-to-get GDHPs around just to tinker.

 

[ddixie884]

Thanx

Here's a scan of the Speer pdf load data sheet for the 135 SBGDHP. Maybe this will help you:

http://www.black-talon.org/RKBA/ammo/Speer_357_GDHP_load_data_sheet.jpg

Thanx for posting this the data at the bottom of the page is great.........