SSN Vet
It ties in nicely with a discussion of various .357 magnum revolvers. Because there is nothing new here, either.
The original pressure rating of .357 Magnum was 46,000 Copper Units of Pressure, CUP. The first revolver in common use to have a problem with it was the S&W M19. It is relatively close to 50,000 PSI although someone would have to point out to me where they saw it rated in PSI. The higher pressure loads are listed in CUP. It was never designed for sustained use of full power .357 magnum loads. One reason S&W was hesitant in following the recommendation of Bill Jordan to build a .357 Magnum on the K frame. The revolver was designed for .38 Special for practice and .357 Magnum for duty. Like everything else, many didn't heed the advisory. Then imported revolvers became very popular. Some were as large as N-Frame Smiths like the M28 mentioned, but were inferior in quality. Most however were about the same size as the K-Frame. With the hotter loads in .357 Magnum, a number of owners were reporting splits in the forcing cone of M19 revolvers and with the widespread use of imports SAAMI's solution was, well, typical. Colt revolvers like the Python and Trooper models had no problems with the warmer loads. Then Ruger introduced the Security Six which put a bite on S&W's K-Frame market. The Security Six was only a tad larger and used a larger cylinder similar in dimensions to Colt's. The real problem for Smith K-Frames was that there is a flat that is cut on the bottom of the forcing cone for cylinder crane clearance, and where the splits occurred. Ruger Security Six revolvers were designed to have clearance without the necessity of the cut. In any event, SAAMI lowered the pressure limit for .357 Magnum ammo from 46,000 CUP, down to 35,000 PSI which is 33,000 in the CUP measuring system. About the time this happened, S&W had already addressed the situation in two ways. First, the M66, the stainless version of the M19 seemed to have no problems with the warmer loads, and the M586 was designed specifically for them. Every revolver made in the US, prior to the M19, were also. Oddly enough, Dan Wesson model 15s had the same cylinder size as the M19, but when Dan Wesson designed it, he addressed the forcing cone issue and used a slightly larger frame in addition to it.
N-Frame Smiths, L-Frame Smiths, Colt's Python, Trooper, King Cobra series, Ruger Security Six and GP-100s and Dan Wesson's M15 were designed for ammunition with the 46,000 CUP pressure limit. The Taurus .357 Magnum built on the M44 frame probably would be suitable if they hadn't decided to drill 8 holes in its cylinder.
The aforementioned Taurus as well as all of their other revolvers, K-Frame Smiths, Rossi's, ALL of the small frame revolvers should be restricted to ammo that does not exceed the 35,000 PSI pressure limit. Sounds like common sense to me. Evidently, many of the powder makers feel the same way because most of them now show loads that go above 35,000 PSI, to near the original pressure max. of 46,000 CUP. Hodgdon and Accurate both list data.
Now, I'm not trying to pick on 2400 here, and I'll try to spread the wealth. But looking at an older manual with 46,000 CUP data, let me tell you what the maximum listed pressures were with the standard 158 gr. JHP, using 2400 and Blue Dot. I'm not going to list load data, just the pressures obtained. Blue Dot: 40,900 CUP, 2400: 41,800 CUP. Blue Dot is capable of higher velocity at the slightly lower pressure. This is where you sometimes see conflict between manufacturers data pamphlets and a reloading manual with independent pressure testing. Also why I recommend load manuals, at least one, that includes pressure data. OK, I mean Lyman here. I like SPEER's as well, but pressure is not given. Even though the max was 46,000 CUP, very few loads crowded the limit. Conversely, look at the pressure rating of the .454 Casull of 65,000 PSI, as well as some of the newer behemoths. Yeah, the original was larger with a 5 shot cylinder, but we have a number of others today not quite as large with six round cylinders. Are they proportionately larger to account for the much higher pressure? Superior mat'ls are the common thread here.
I've used all of the powders mentioned here except Li'l Gun. As I mentioned, I believe it to be slightly slow for the cartridge and this is somewhat based on the use of H110. One thing you'll find common to H110 and W296 is that they rarely chronograph velocity near what is shown by manufacturer's data pamphlets. Look at the older Component manufacturer manuals and you'll see exactly what I'm talking about, By the time you get to chronographing, you won't have much doubt, and whatever you have will be eliminated after chronographing.
Now, is it necessary to have the highest velocity possible when you're shooting your revolver? Most often, it's not. Of course, I feel the same way about muzzle blast. But, if you are going to use a .357 Magnum to harvest deer, you want all of the velocity possible, so long as it's matched by accuracy. This is how you get the higher muzzle energy, and sometimes, as is the case of a recent thread, there is a mandated minimum for Kinetic Energy of your handgun load. Moreover, a lot of the acceptable minimum caliber debate starts right here. Many of the Gun Rag articles told you that .357 is marginal for whitetail deer, but they didn't tell you why. Makes sense because ammo manufacturers make up a good deal of their revenue. My opinion? Don't use factory ammo for hunting whitetail deer with a .357 Magnum revolver!
Why do I like AA#9? Because at max loads it WILL chronograph what you think it should and at 25 yards, you should find groups under 1" and under 3" at 50 if you're capable of dealing with recoil and have a decently accurate revolver. It has less muzzleblast than 2400, 110, or 296 and at the start charge level it is the equal or superior to all of them. I have found the same true in .41 magnum as well as a few others who have ACTUALLY tried #9.
I know my opinion is a little different here, but I'll tell you, if we were talking about 4" revolvers, the recommendations would still appear the same without consideration of how peak pressure is effected by barrel length. I have even seen guys state that they don't believe there is an effect because revolver cartridges pressure peak at the casemouth of the cartridge. They don't have the Lyman manual, or have never read the article that covers this, that's in it. For the guys that are fortunate to have the Quikload software, all you have to do is enter the data. It will show you time to peak pressure and accounts for barrel length. The burn rate requirements of the .357, .41 and .44 magnums are NOT the same.
