This is part 2 of my report......
I still recommend you stay with the P32 if you want a .32acp to carry. The Cobra derringer is mainly a novelty. It fires OK and recoil is surprisingly low, lower than the P32. But if you have large hands like mine you can only get a 1 and 1/2 finger grip on it. It's necessary to sorta pinch the grip with your thumb, as shown in the picture. Then it grips OK. I use a second hand over the back of the grip hand. With the low recoil, I guess a lady with small hands could shoot it fine. And it is very small, easy to conceal. (My dealer friend calls it a "pimp" gun. He let me have it for $109 OTD. Very few distributors have it in .32acp. Plenty of 38spec available which has a bigger grip.)
Accuracy was OK at the short wetpack distance. Didn't get to check it out on a target, my hands got too cold and I went home.
Mechanical design of the Cobra is an aluminum frame and barrel with stainless tubing barrel inserts. Rifling is minimal, just barely visible grooves produced during installation of the liners. Seemed to be a good job, an unfired bullet would not drop in the barrel, so that's OK. I did a little calculation on the barrel, comparing it to the P32, with the following results. (Neither has a very high safety factor and that's why I don't recommend +p ammo, such as CorBon stuff, in either pistol.)
P32 barrel 0.393" od minus bore 0.311" diam leaves wall thichness, t, 0.041" near the chamber and a mean radius, R, of 0.176"
for the 4140 heattreated steel, yield point is around, S, 130,000psi.
plug this in the simple formula St/R=P gives 130000 x .041/.176 = 30,284 psi max allowable pressure.
then compare this to KelTec's ballistic data http://www.kel-tec.com/new_page_12.htm and use their expected max pressure of 12950 psi, gives a safety factor of 2.3
There is a groove in the P32 barrel up near the front, but pressure drops low enough that the groove is not a concern.
Cobra barrels are 0.550" diam minus the .311 bore leaves a wall thickness of .119" and a mean radius of about .215"
assuming they used a 355aluminum alloy casting with yield point around 27,000psi, and taking no credit for the .045" stainless steel liner,
plug into the formula above gives 27000 x .119/.215 = 14944 psi allowable, for a safety factor of only 1.2
safety factor is a little higher if pressure is based on the tensile strength for 355aluminum of 40,000psi. And the stainless liner adds some strength, I just don't have a way of knowing how much. A proof test to destruction would be needed.
So I can only conclude that the Cobra derringer is barely good enough for standard factory ammo. The manual packed with the gun says so too. And if you want to carry one, use std. FMJ ammo, don't waste money on JHP.
og..........does the P32 has a OSS rating of 97.3%??? EM, gotcha, if ur readin this :P