+p Kahr's

[Scibaer]

According to kahrs site, all kahr models are rated for +p ammo.
 i personally dont need +p ammo, but i did a search and did not find any factory ammo in +p for the .40 S&W
i look at the Hodgdon webite, reloading page. i didnt find any hand loading data for .40 ammo in +p configuration either.
 it could be because its still a new caliber, and the ammo companies had not focused on +p ammo, because of the lack of demand.
i'm going to research overpressure ammo and see what the saami specs and requirements are.
i think  i want to handload some +p ammo for my .40 and see what results i get.
 anyone else have an interest in +p for thier kahr ?

[Scibaer]

researching +p ammo, i came across this statement on Wikipedia

 "  Even in the same firearm, with the same components, cartridges with low powder capacity and high operating pressures, such as the .40 S&W, have been shown to have a significant increase in pressure with very minor differences in bullet seating depth. One example in .40 S&W demonstrated a 20% pressure increase with a 0.05 inch (1.2 mm) change in seating depth"

bolding is mine, showing that at least in the .40S&W it takes very little to get a over pressured cartridge.
i personally dont have a way to test or measure chamber pressure, other then using a chronograph.

[Chickasaw Hunter]

The +P descriptor was used to describe/warn that an older cartridge was loaded to a higher pressure and should only be used in more recently mfg'd firearms. The first I remember was .38 spl's loaded to higher pressure and was only to be used in newer pistols. The +P disagnator caught on with other calibers and became a standard for established calibers that were loaded to a higher pressure level. All of this happened long before S&W brought out the .40, so when the .40 S&W hit the market all the pistols were new, there were no old .40 S&W loading levels to increase. So the .40 sorta came on the market already a +P. Maybe someone is using the +P labeling as a marketing ploy, but for me I'd stay with the published loading data for the .40 S&W because it is truly a new cartridge. If I were really trying to bump up the .40 S&W to a higher level of performance, I'd go with a 10mm. YMMV. CH

[Scibaer]

Yep, i agree with all of that.
i found it interesting that the wikipedia entry mentioned that the .40 was pressure sensitive.
kahr does say on thier site, that all kahr handguns are rated for +p ammo. so its just something that i'm looking into, i find anomalies interesting.
 

[helotaxi]

It's easier to say all than it is to say "all .45, 9mm, and .380Auto."

If you explore the history behind the .40 S&W you'll realize that the idea of a +P load in that cartridge doesn't make sense since it is a "-P" loading of the 10mm.  If you want something more potent than the .40 go to the 10.

[Scibaer]

i have been looking into the .40 , its development and history.
and your right, its a detuned 10mm and not really +P material. i made  3 +p cartridges for it and i could really tell the difference, not something i'm going to do again, the gun didnt seem to mind, but they didnt shoot well and the muzzle flash was nasty with unburned powder spitting out from the barrel.
i didnt really need or want a +p .40 round, it was just something to look into and see "for my self" type of thing

[Chickasaw Hunter]

+P slipped into our vocabulary because .38spl (mostly) .44spl and some others were originally blackpowder cartridges. Then better smokeless powders came along and there was still a lot of pistols out there that were designed for blackpowder. So commercial mfg's loaded to a safe load for everything that was out there. As time worn on and most of the firearms in use became of more modern mfg with better metal and metallurgy some smart marketing guy came up with the term +P so they could sell hotter ammo and the guy who had the Forehand break action .38 special "should" know it wasn't for his 1921 revolver. So fash forward to somewhere in the 80's Smith decided to take the .40 down off the shelf and introduce it. Semi-auto sales were booming and it was time. Smith actually developed it about 1971 (IIRC), but didn't see a market for it so they shelved it until the semi-auto craze took off. Think Sonny Crockett and his cool Jackass/Galco shoulder rig, everyone had to have one. So as I mentioned above the .40 was a "new" cartridge that didn't need to be loaded to a higher level so the +P concept didn't really apply to it. Now days the +P term is in common use and has extended itself to all kinds of ammo. .45ACP for one wasn't a blackpowder round but we use the term for hotter .45 ACP loads. I've noticed it's even now being used with .257 Roberts loadings. And it works just as it was originally used. Lots of original .257 Roberts were built on older mil surp rifles and as powders became available and pressures went up loads now possible in a Roberts round were'nt safe in your old Crimean War Veteran rifle. So +P designates a hotter load. CH

[pneuby]

Your Kahr will safely handle all .40. Don't mess it with experimenting with it. Due to what Scibaer posted, be especially conscientious as to OAL, and seating depth. I'm not fond of the caliber, though I've given it a better than honest shake over many years, and several guns. Not that it would ever do so...but I wouldn't miss it one wink if it disappeared tomorrow. 

[Squib]

the big issue I've read on is "bolt thrust".  .357 sig is suppossed to generate even more thrust than a hotter .40, and break frames quite often.  don't try putting a .357 sig barrel in your frame and expect it to NOT make you sorry. 

I could be wrong though, I haven't tried it.

[bpiatt]

Before you go trying to reload some +P or hotter than factory .40's, ask yourself what you want to achieve?

180 gr. factory .40's have more than adequate penetration, almost too much.  If you want more speed / less penetration, then there are 165 gr. or even 155 gr. factory loads with plenty of speed.

I can tell you that the lighter factory loaded bullets, there is more muzzle blast. 

[cheapshooter]

i think  i want to handload some +p ammo for my .40 and see what results i get.

That is what the Glock 20, and 29 are for 10MM
40 S&W +P doesn't exist because it would not be safe!!! Factory 40 is already loaded close to max.