38+P vs 357 in a 38 Case

[m0ntels]

Like everyone else and their momma, I have a 642 Smith and Wesson. It's rated for 38+P of course. From anything I've ever read, +P just means hotter than SAAMI, but no defined upper limit. After talking with a few people about loading 38 Specials with 2400, I decided to try a few 158s. I got out an old loadbook and it listed 2400 for 38 Special from 9.0 - 11.0 grains. The book WAS new enough in that it had 357 loads in it and it had up to 15.0gr of 2400 for a 357 case IIRC.

At what point does a hot 38 Special become a 357 Magnum in a short case? Velocity of the 38 was listed just under 1200fps in a pressure test gun. The 11.0 gainers went off like a cannon, but were pretty accurate, and fell right out of the cylinder after firing. I did work my way up to that point btw, I aint too crazy! I dont have a chrony to determine how fast these guys were really going. I dont plan on using these as an every day practice load. I just want to know where the limits of safe +P loads are. I know it's an aluminum frame, but at the same time, it says +P right on the barrel.

As far as why I wanted 2400 38 Special loads, some people have said a slow powder will still work the same in a short barrel as it will in a long one. They nay-sayers all said things like extreme muzzle blast and unburned powder, but with non-mag primers, I had hardly a speck of unburned powder and at least from the rear I didnt see any muzzle flash. I love 2400 in 357 Mag, so I wanted to see it in 38, just because I could...

Randy

 

[Sleeping Dog]

If your old book doesn't have a section on .38 Special +P, get a new book. Or, go to powder manufacturer web sites or bullet or brass manufacturer sites and check their data. My Speer reloading book (edition 13?) has a few pages with +P data. As expected, it's more than .38spl, less than .357mag.

The only data I saw with 2400 was for use with a 200gr bullet, on an Alliant page: http://recipes.alliantpowder.com/rg.taf?_function=pistolrevolver&step=2&bulletID=49&cartridgeID=1018&caliber=%2E38&cartridgedescr=Special%20%2BP&bulletdescr=200%20LRN

Overloading won't blow up your gun, probably, but it will put it out of spec sooner.

Regards.

 

[m0ntels]

I have over a dozen loadbooks a year or so old, so I do have +P data in there. I just got a few pre-lawsuit craze books for comparrison. Not too much seems to have changed in the last 50 years too much, at least not for metallic loading. Some old loads are a bit hotter, and some are a bit milder than they are today. I dont really shoot +P often at all, I just want to know more about top end loading just so I know it. I got a 686 if I want to play with 357 mag level stuff, and a 41 for fun after that.

I have some Blue Dot I havent gotten to try yet too.

Randy

 

[griz]

If my source is correct, the SAAMI limit for 38 special is 17K, and the limit for +P is 20K. I don't know if there is an established limit for +P+, nor do I know the limit for 357s. You can certainly exceed the +p limit. How far depends on how much of your safety margin you want to use up. 2400 is probably a good powder if you want to get near the edge. But I would be cautious without a chrono.

 

[facedown]

I have some Blue Dot I havent gotten to try yet too.

By all means, work up some Blue Dot loads. It is, relatively, a slow burning powder so the loads listed are what is necessary to develop the corresponding pressure/velocity. The main advantage is that the recoil is "softer" for a given p/v, more like a "thump" than a "kick".

The coolest part is that since not all of the powder burns before bullet exit, it throws an impressive flame downrange.