Need dimensions/drawings for modern .38 Short Colt cartridge.

[tbx-4]

Like the title says I'm looking for dimensions and or drawings for .38 Short Colt cartridges (.357 boolit, not .375 heeled).

Thanks.

[Bigslug]

Starline lists their case length for the Short as 0.754"-0.761", and the Long as 1.019"-1.026".

15th edition of Cartridges of the World lumps the Short and Long together (which is weird), but is clearly using the Short dimensions in their table of cartridge specs:

Bullet diameter: .357"

Neck diameter: .357" (Which is an obvious typo. They're meaning outside diameter of the case mouth, which is listed as .379" on the .38 Special and .357 Mag.)

Base diameter: .378" (.379" on the Special and .357 Mag)

Rim diameter: .433" (.440 on the Special and .357 Mag. I've shot Short Colts in a J-frame .357 - with no issues but you might want to factor that in to reamer design if you're planning to cut Special brass. You might also check with Starline to confirm if they're using that number for their rim or just making a short Special case. I doubt 0.007" among friends means a lot.)

Rim thickness: .055" (.054 Special, .055 .357 Mag)

Case length: .76"

Cartridge length: 1.10" (though I expect there's a wide fudge factor in there. Wiki - "trustworthy" Wiki - says the Short was originally a heeled bullet load - .375" diameter for cartridge-converted '51 Navy Colts. The ammo using .357" bullets appears to have never had a gun made specifically for it, and was made - presumably as a dialed-down option - for use in .38 Long Colt guns. COAL therefore is probably whatever your combination of cylinder/throat, bullet shape, and twist rate allow it to be.)

Lee lists the Short Colt in their "Custom run, but on hand and available" case-length gauges/trimmer pilots, so obviously they have a range for "trim to" length. They also do a die set for Short/Long.

[tbx-4]

Bigslug,
Thanks for the info. I'm trying to get enough details to have a finish reamer made. This is actually for a single shot rifle but since it's a pistol cartridge I thought I'd ask here first.

[Traffer]

https://en.wikipedia.org/wiki/.38_S%26W
https://en.wikipedia.org/wiki/.38_Short_Colt

[FergusonTO35]

Cool project. I'm currently working on "high efficiency" loads for the .38 Long Colt. I think one reason wadcutters are so accurate is that there is less empty space in the cartridge than with standard slugs. The powder burns more completely and is less position sensitive. I think that .38 Long Colt brass would be ideal for this project using regular SWC or RNFP slugs.

[Bigslug]

Cool project. I'm currently working on "high efficiency" loads for the .38 Long Colt. I think one reason wadcutters are so accurate is that there is less empty space in the cartridge than with standard slugs. The powder burns more completely and is less position sensitive. I think that .38 Long Colt brass would be ideal for this project using regular SWC or RNFP slugs.

It's a workable thing. My Dad had a cast-frame Ballard with the original .38 Ballard Long (heeled round) bore completely toasted sleeved for .38LC so there would be no possibility of a +P .38 Special finding its way in and causing damage. I forget the Accurate Molds catalog number he ended up with, but it's got a wide BP lube groove and runs 154-155 grains. Been a couple years since we've had it out, but as I recall, a case full of Triple 7 gets it up to about 900-1000 fps out of the 30" tube, and it is comfortably minute of dog food can at 100 yards.

The .38 SC has been rattling around in my head for a couple of things. First, I wish that some of the gun manufacturers would latch onto it with a shorter cylinder revolver - a mini J-frame, if you will. Secondly, I REALLY wish somebody would commercialize it as a flat nosed round and make a tube-fed pump-action rifle for it - kind of a Winchester 1890 on steroids. I like the idea of using it to duplicate the various .38S&W loadings, but using the common "modern" .38 Special diameters for brass and slugs. The single shot concept just seems like a lot of fun!

You'll definitely want to tell your reamer manufacturer what you're up to - I don't know if a reamer for making revolver chambers would be a different animal from one that's designed to bore out the back of a rifle barrel. You'll probably want to pick Outpost75's brain on the throat - the typical old black powder rifle usually doesn't have one; only a slight bevel where the rifling starts. May or may not be ideal for what you've got in mind.

[FergusonTO35]

I agree that a short .38 cartridge loaded for modern revolvers would be a winner. All that extra space in the cartridge serves little purpose other than to keep it from chambering in a top break. Sadly there are too many of those still floating around to make it commercially attractive. Another good reason to reload!

[tbx-4]

...You'll definitely want to tell your reamer manufacturer what you're up to - I don't know if a reamer for making revolver chambers would be a different animal from one that's designed to bore out the back of a rifle barrel. You'll probably want to pick Outpost75's brain on the throat...

Yes, I want to talk to someone at Dave Manson's about the details. What I'm thinking is a .38 Spl rifle reamer shortened to the .38 SC length. Don't see why the throat would be that much different.

[Outpost75]

SAAMI .38 Special and .357 pressure barrel chambers really have no "throat" as such, but simply a 15 degrees, Basic transition from the .379" diameter case mouth, to groove diameter with no freebore.

The .357 NRA reamer John Taylor uses is based on the .38 Special Army Marksmanship Unit wadcutter chamber used in the Colt .38 Special National Match pistols, the only difference being that the chamber length was made for the .357 case. Factory .38 Special wadcutter ammunition is very accurate when fired in this .357 chamber and the very gradual tapered forcing cone departing directly from the case mouth, with no ball seat handles all bullet types well. In NRA testing several Marlin rifles and T/C Contender pistols were fired first with the standard SAAMI chamber, then were rethroated with the AMU wadcutter throating and the improvement in accuracy was dramatic.

When I was at Ruger the company produced a run of .357 Magnum No.1 rifles as a CHP commemorative and some of the guns were returned to customer service for accuracy complaints. Testing the customer service returns with .38 Special wadcutter, 158-grain lead +P and 158-grain JHP .357 loads before and after rethroating paralleled the results from the NRA tests and simply rethroating cured all of the accuracy problems.

I have a BSA Martini Cadet rifle with Green Mountain barrel which John Taylor put together for me and chambered .357 with that reamer. Good .38 Special factory wadcutters fired in that rifle off sandbags with 6X Unertl scope average under 2 inches at 50 yards for a long series of 10-shot groups, with the best lots of ammunition under 1-1/2" whereas handloaded 158-grain Hornady XTP or Sierra GameKing bullets in .357 Magnum with 4227 powder are consistently 1-1/2" to 2" at ONE HUNDRED YARDS!

Not bad for a 6-lb. hunting rifle with full-length military stock!

John's suggestion to use the .357 NRA reamer stopped short and cutting the rim seat separately is the easiest option, avoiding the $200+ cost for having a custom reamer ground, as .38 Short Colt would not be a stock item.

[FergusonTO35]

Outpost, you da man as always!

[FergusonTO35]

Just ordered a bag of .38 Long Colt brass. I have read that some competitive shooters load 9mm equivalent loads in .38 Short Colt brass for faster reloads in .357 revolvers and it handles them just fine. They also say that the short case doesn't affect accuracy. No way would I do that, but I see no reason why .38 Long Colt brass wouldn't make for a more efficient standard pressure .38 for my snubbies. The often wide velocity spread produced by standard .38 Special loads in a snubbie is really irritating to me!