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Thread: the P32 compared to a Cobra .32 derringer

  1. #1
    KTrange Contributor oldgranpa's Avatar
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    the P32 compared to a Cobra .32 derringer

    cloak asked for this......I found a range open 40 miles from home so I could do this test before the Holidays begin. my report is in 2 parts.
    This is part 1, a brief wetpack test comparing the Cobra derringer model .32acp with the KelTec P32. We already knew what Winchester Silvertip JHP would do with the P32 from previous tests. And we knew Speer GoldDot wouldn't expand with the P32. But I wanted to test a new box of Federal HydraShok JHP 65gr that my dealer ordered for me. So I put both pistols to the test. Results are as expected. The Silvertip partially expands in the short barrel (2.375") derringer, much like it did with the NAA Guardian and Beretta Tomcat in my last test. Silvertip often partially expands with the P32 also. Penetration was 6+ inches.
    The Speer GoldDot again did not expand. Penetration 7".
    The Federal HydrShok did not expand with the derringer and you can see the expansion results with the P32 in the picture. The HS has a heavy copper jacket and the expansion with the P32 is mostly the petals which are very stiff and sharp. Penetration was 7". This would be a good carry round for the P32.
    The FMJ rounds penetrated 8 to 9".
    Weather was very cold so I limited this test. Will do more next year in better weather.

    og
    Attached Thumbnails Attached Thumbnails the P32 compared to a Cobra .32 derringer-derringer_p32_wetpack.jpg  
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  2. #2
    KTrange Contributor oldgranpa's Avatar
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    Recommendations.....

    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.

    FWIW,
    og..........does the P32 has a OSS rating of 97.3%??? EM, gotcha, if ur readin this :P
    Attached Thumbnails Attached Thumbnails the P32 compared to a Cobra .32 derringer-derringer_grip.jpg  
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    Junior KTranger The_Shootist's Avatar
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    Test Results?

    Great stuff, oldgranpa! I've been waiting for a second opinion on the Federal H/S's. I switched to them after seeing Golden Loki's tests in gelatin, making them out to be a decent .32 acp round for the P-32.

    Must have put about a 100 (at least) H/S rounds through my P-32 all problem free. Luckily for me, I can pick them up easily at a local gunshop - or if they are out get same week delivery from cheaperthandirt.com
    There are terrorists among us
    And its a game of take and give
    But the man who draws the fastest
    Is the only one who'll live!

  4. #4
    KTrange Contributor cloak's Avatar
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    Hey OG,
    Thanks for posting this. The main reason I got the derringer was for up close and personal stuff, basically if I had to shoot at close range and I couldnt get to anything else. The rounds Im carrying in it are just standard FMJ. Its good to see that the silvertips opened up out of such a short barrel. It does look like the cobra is a shorter barrel wise than the p-32.

    Is EM made it personal between you and him yet??

  5. #5
    KTrange Contributor oldgranpa's Avatar
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    hi...

    hi cloak,
    no doubt, the little derringer will fire a FMJ with good penetration. And low recoil to boot. Great, nice looking, little collectors gun for such a low price. And fine for a last ditch hideaway.
    EM banned me from his site a long time ago. He reads our site but won't register and post anything. So I just enjoy ragging him now and then.
    have a safe holiday season.
    og
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    shoot i got one i bought 15 yrs ago

    its a davis d-32 but it looks just like the cobra.. rosewood grips and nickel quite pimpish... lol but i like it its been fired 21 times in 15 yrs but it always goes bang.. no matter how long between firings.
    keltecing across the universe

  7. #7
    KTrange Contributor TxCajun's Avatar
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    Cobra bought out Davis. Same guns - different name. I used to have a Davis P380. It was small but heavy - cheap but sturdy. Went bang every time... made in California... lifetime warranty.


    "Patriotism is supporting your country all the time and your government when it deserves it."
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  8. #8
    KTrange Contributor cloak's Avatar
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    I went to the range yesterday and my brother fired the derringer. He was holding it way too high and I saw the round hit the tile at the end of the range( actually where it hit the tile). He tried it again and actually got it on the paper. I showed him about how far to use it. Since most of the self-defense situations usually are 21 feet or less, I ran it out at 7 yards(21 feet). Put 2 in com. then moved it to 3 yards, 2 more com shots. Then 2 headshots right next to each other. I even let a couple of women who practicing for qualifications fire it. 7 yards. they were able to hit the torso area with it. Then I let the range guy fire it.. We all agreed that it would be a good up-close and personal gun. After out little discussion, I started point shooting with it. The safety can be a pain to disengage, but I found that if I have it my right pocket, I can sweep it off, and have the trigger pulled to full cock before it comes out of the pocket. I practiced that for about an hour unloaded before I went.

    It is a back up gun. Plain and simple. It will fit in a Levis denim jacket pocket quite easily.

  9. #9
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    Top and bottom barrels combined mean velocities
    Winchester 71 gr FMJ averages 768.95 fps 93.198 ft lbs (Box rated at 905 fps 129 ft lbs from a 4" barrel)
    Remington 71 gr (71.5 gr Actual) FMJ averages 838.633 fps 111.636 ft lbs (Box rated at 905 fps 129 ft lbs from a 4" barrel)
    Fiocchi 73 gr (73.4 gr actual) FMJ averages 827 fps 111.445 ft lbs (Box rated at 980-1000 fps 155-162 ft lbs from a 4" barrel)
    Fiocchi and Remington both have nearly the same amount of recoil.

    Reload#1: 54 gr '00' Buck .33" lead round ball sized to .311" lead round nose loaded with 2.5 gr Alliant Bullseye (BE) powder cartridge overall length at 0.82" deepest averages 876.45 fps @ 92.13 ft lbs
    At 0.845" OAL the 00 buck w/ 2.5 gr BE = 842 fps ~85 ft lbs
    02/16/2015
    At the deepest possible seating ~0.81-0.82" overall length the 54 gr 00 buck 2.5 gr BE load will average 909.5 fps and 99.16 ft lbs.
    Reload #2: 47 gr 0 Buck .32 Lead round ball unsized crimped in case with 2.4 gr of Bullseye Powder averages 825 fps @ 71 ft lbs. At 2.5 gr BE the 47 gr 0 buck will achieve 76.2 ft lbs. Loads that exceed 2.6 gr don't get much faster than 2.5 gr with the 47 gr 0 buck. Shooting an 0 buck ball loaded with 2.5 gr BE at redwood planks would penetrate 1.875 inches and the 00 buck at 2.4 gr BE would penetrate about 2.2 inches.
    None of these reloads above bulge or expand cases more than standard pressure factory ammo.

    The Cobra .32 ACP derringer alloy is actually made by International Die Cast in Gardena, CA, just recently engraved on 2014 and newer derringers, so it should be made with ZAMAK-3 zinc alloy (better than 355 aluminum alloy), yield alloy casting with yield point around 30,200 psi, and taking no credit for the .045" stainless steel liner, plug into the formula above gives 30,200 x .119/.215 = 16,715.34884 psi allowable, for a safety factor of only 1.29076.
    Good enough for all standard pressure rounds up to Fiocchi 73 gr FMJ and Remington 71 gr FMJ Box muzzle energy rated less than 130 ft lbs. The Cobra recommends factory 128 ft lb rated cartridge brands like Federal American Eagle, CCI, Blazer, and PMC for safe handling. Max allowable cartridge: 128 x 1.29076 = 165.12 ft lbs. Don't shoot any round hotter than Fiocchi 73 gr FMJ and Remington 71 gr FMJ.

    The Cobra 32 ACP derringer's sized .311" diameter 54 gr '00' buck lead slugs can go through three and four tenths to all four of 5/8 inch of dry hard pine and redwood wood planks (cheap scrap wood) (about 2.325 to 2.4+ inches) that are wood glued all shot within five feet away from the muzzle. The '00' buck slugs and FMJ bullets that went through were not recovered.
    At 640 fps (~49.1 ft lbs), '00' buck .311" caliber shotgun slug shaped bullets" can go though 1.25 inches of those wood glued planks and embed in the third one halfway. None of the pellets were deformed.
    The sized to .311" 54gr lead .33" '00' Buck penetration is better than unsized .33" lead round ball because of their lower surface area and short Makarov bullet or shotgun slug shape with flat to round sprued bases.
    All 32 ACP 71 gr FMJ's and sized to .311" caliber 54 gr '00' buck at 90+ ft lbs can go through all four of those planks (2.4"+ of wood glued pine boards) within five feet of the muzzle as long as they don't keyhole upon entry.the P32 compared to a Cobra .32 derringer-imag0140.jpgthe P32 compared to a Cobra .32 derringer-att_1421819322825_imag0114.jpgthe P32 compared to a Cobra .32 derringer-att_1421994773922_imag0036.jpgthe P32 compared to a Cobra .32 derringer-imag0054.jpg
    Last edited by brian_pdll; 03-13-2015 at 11:27 PM.

  10. #10
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    Cobra .32 ACP Derringer Ballistics 1

    Here are some more photos of the Cobra 32 ACP derringer tests. '0' and '00' buck reloads were very accurate out of the derringer within 50 yards. All reloads that were approximately 80-103 ft lbs felt like standard pressure factory 60-65 gr JHP and Winchester 71 gr FMJ at most.
    Remington 71 gr round nose FMJ was the most potent of the standard pressure factory rounds and absolutely no problems with all loads in the derringer.

    The derringer's recoil with this caliber felt like shooting a standard pressure .38 Special to .38 Special +P out of a steel j-frame with wood grips. Semi-hot 73 gr Fiocchi FMJ felt like a 9mm Makarov from a standard Makarvov pistol and Winchester 71 gr FMJ-Flat point felt like .38 Spec standard pressure from a steel j-frame (very manageable)

    Too slow to shoot and reload for SHTF or against more than one attacker with the will to kill. I recommend using factory Remington 71 gr round nose FMJ (110 ft lbs) because they keyhole, do more damage than sized 54 gr lead '00' Buck due to higher muzzle energy with good penetration for protection. Sized 54 gr lead "00" Buck with 2.5 of BE powder would be a respectable second choice in this caliber because it gets more than adequate penetration capable of pin point accuracy, since hollow points don't get enough penetration in ballistics gel.the P32 compared to a Cobra .32 derringer-imag0057.jpgthe P32 compared to a Cobra .32 derringer-imag0063.jpgthe P32 compared to a Cobra .32 derringer-imag0081.jpgthe P32 compared to a Cobra .32 derringer-imag0106.jpgthe P32 compared to a Cobra .32 derringer-imag0117.jpg
    Last edited by brian_pdll; 02-21-2015 at 12:01 AM.

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