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Old January 20, 2013, 02:26 AM   #7
Sevens
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Join Date: July 28, 2007
Location: Central Ohio
Posts: 8,472
I have a couple of issues with some things on the page. Otherwise, he does make an interesting argument.
Quote:
Also, the 10mm was designed for a peak mean pressure higher than the .40 … which means the 10mm brass is engineered to handle greater pressure than the .40 case.
While it's true that the 10mm was designed for a higher peak pressure than the .40 S&W (37.5kPSI vs 35kPSI), it's not by a huge margin. But more to the point, 10mm brass is inherently weaker than .40 S&W brass, and that's due to the 10mm's insistence on a large pistol primer, the pocket of which eats up important case head real estate. Gonzo "blow 'em all up and learn from it" handloader and forum legend Clark has taken ridiculous .40 S&W brass loads further than he could push similar loads in 10mm brass. That primer makes a difference.
Quote:
As mentioned above, the .40S&W was never intended to be a high-pressure round like the .357 Magnum, 10mm, or 357SIG. In fact, the SAAMI (Sporting Arms and Ammunition Manufacturers Institute) specification for the .40S&W is the same as the 9mm spec (35kpsi).
Wow, tough argument. He claims that .40cal was never intended to be high-pressure at 35k, the same as 9mm, which -IS- high pressure, and same as .357 Magnum (also 35k) and just a blip below the 10mm and .357 Sig.
News: all of these are high pressure handgun rounds. If you want LOW PRESSURE handgun rounds, you are talking .38 Special, .32 S&W Long, .45 Auto. But SAAMI spec'd at 35kPSI max, which the .40 S&W is... is high pressure. There are a couple higher, but not many.
Quote:
The 165gr is really the optimum choice for .40S&W shooters. It tends to be more accurate, have greater muzzle energy and momentum, and it significantly reduces the dangers associated with possible bullet setback (a bullet can, through normal handling, seat itself more deeply just by being loaded into the chamber of a gun, etc).
I have to argue with his assertion that the 165gr slug greatly reduces the dangers associated with bullet setback.

In fact, I do agree there are SIGNIFICANT dangers with regard to bullet setback, and I also believe that unintended and/or unnoticed bullet setback is likely the leading cause of otherwise unexplained or "theorized" reasons for KB's, especially when they occur to a handloader.

His argument is that a shorter 165gr slug eats up less space -- which makes every tiny bit of unintended/unnoticed bullet setback a bit less dangerous. That certainly could be the case.

However, my assertion is that a shorter 165gr slug does precisely that: it offers MORE space inside that case, and much less resistance to bullet setback. Where as the longer 180gr slug is much more resistant to bullet setback because:
a) there's less room to move, powder pushing back from under the slug*
b) no matter what slug was originally loaded in that brass, reloading with a 180 is putting fat bullet shank deep in to the brass, resulting in more bullet pull and more case mouth tension, reducing the chance of un/un bullet setback.
(*as I understand, this is one method that handloaders use to safely address such concerns with the .357 Sig at the load bench)

I realize fully that I'm making theories and assumptions of my own, but that's just as I see it. My theories are backed by over 3,000 loaded and fired rounds of .40 S&W...and I've not yet loaded any bullet weight in .40 S&W except 180 grain.

And there's a WHOPPER that he never once mentions while he's quite quick to talk about the myriad of KB's in .40 S&W chambered pistols: The 10mm Auto that was the predecessor of the .40 S&W was a smaller, .40cal hole drilled through a fat .45-gun sized barrel with beefy steel surrounding the chamber and launched from .45cal frame sized handguns.

Smith & Wesson and Glock, when they hit the market with this new round delivered to the shooting world a new round... NOT with a .45-sized frame and utilizing a smaller .40cal hole through a larger .45cal barrel with fat steel around the chamber... they gave the world 9mm frame sizes with 9mm barrel sizes and LARGER holes bored through them resulting in less critical steel surrounding every part of the round. And they used the same 35kPSI max in the cartridge.

When they made a 10mm from .45-sized handguns, they made a smaller hole and upped the pressure. They did the opposite with .40 S&W, they kept the same (high) pressure and bored away more steel.

As I said up front, I do think he's put a lot of time and thought in to his argument and I gained something from reading it.
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