Modify a KT-P3AT to shoot 9x18?

Discussion in 'P-3AT' started by cromanos, Apr 8, 2009.

  1. cromanos

    cromanos New Member

    151
    Jul 22, 2008
    Has anyone done this, or considered it? My thinking is that the .380 and the 9x18 are close enough (as evidenced by the fact that both Makarov and CZ use the same mags for both calibers) that a Kel-Tec P-3AT barrel could be modified by a competent gunsmith to shoot 9x18. The .380 is a .355, and the 9x18 is .364, so you're talking less than 0.010" difference - I'd expect the barrel to be able to handle that as-is. Cheaper, more available ammo, with quite a bit more punch.

    I've posted this on the Makarov forum as well, to see if anyone has done it.

    Thoughts?
     
  2. rcmodel

    rcmodel New Member

    Feb 6, 2005
    Eastern Kansas
    Seems like a bad idea to me.

    The MAK groove dia. is .366" as opposed to the .380's .355".
    So, the bullet is .011" too big. Without re-boring & re-rifling the barrel, that would raise pressure considerably. There isn't much barrel wall thickness there to start with, and removing .011" from the barrel and .018" from the chamber seems unwise.

    The MAK case & rim is .392" (Very similiar to the 9mm Luger rim size) and the .380 is .374".


    .018" in case dia. is quite a difference, and the slide would have to be milled out to provide clearance. Also the extractor modified to fit the larger case.
    This would make the slide slightly lighter, and if anything, it needs to be made heavier to contain the heavier MAK recoil impulse.

    In addition, one MAK round will not fit in a P3AT magazine, let alone five, which is all there would be room for if they did fit.
    A magazine wide enough to hold the rounds would not fit in the grip.

    Then you get to the design limitations of the gun itself. The P3AT is pushing the design envelope in every area to contain the .380 cartridge.

    The MAK, although similar to the .380 in performance, develops about 230 - 240 ft/lb of energy, as opposed to the .380's 190 - 210 ft/lb.

    That is over the design limits of the P3AT, and would quickly batter the gun to death.

    Keep in mind that the Makarov and CZ were both designed from the start for the more powerful & larger round, and were later modified for the less powerful & smaller .380.
    Not the other way around, as would be the case with the P3AT.

    rc
     

  3. joje

    joje New Member

    213
    Nov 1, 2007

    it may not sound much but a 9x18 bullet is really too wide to ride through a 380 barrel. also the 9x18 is more difficult to come by, (at least normally) the choice of SD bullets is very limited, and it really doesnt have a lot more punch. it may be right in between the 9x19 and the 380 in terms of case length, but like the 380 it is a low pressure round designed for blowback actions, and its ballistics are very similar to to the 380. the 9x19 gets its ballistic advantage due to its capability of handling much higher pressures more than anything.


    for said reasons its common that people do the opposite conversion on their makarovs, but this conversion do require a complete barrel swap.
     
  4. cromanos

    cromanos New Member

    151
    Jul 22, 2008

    it may not sound much but a 9x18 bullet is really too wide to ride through a 380 barrel.[/quote]

    I think I may have miscommunicated my original thoughts.  I did not mean to imply that the existing .355 barrel could handle the .364 bullet, only that it could be bored out, rather than have to be re-designed, to handle it.

    As far as availability goes, I've seen much more 9x18 on the shelves than .380, although I expect that to change at some point. Limited SD ammo choices are admittedly a concern w/ 9x18.

    That said, perhaps a PF9 or P11 would be better platforms for conversion. As somebody rightfully pointed out

    I guess I'm approaching the issue because I already carry and stock 9x18, and would like to have a pistol in that caliber for summer concealment as well.

    Perhaps a PF9 or P11 would be a better platform for conversion. As rcmodel correctly pointed out, both the Mak and the CZ82 were designed for the 9x18, then adapted for the less powerful .380, which required little more than a barrel swap and a lighter recoil spring, rather than adapting a .380 for a more powerful caliber. I checked out the specs on the PF9 and the P11, and both would be lighter and smaller than either a Makarov or a CZ.
     
  5. rcmodel

    rcmodel New Member

    Feb 6, 2005
    Eastern Kansas
    The problem there is both are locked-breach designs designed to operate at the 9mm Luger's 35,000 - 38,500 PSI pressure range.

    The 9mm MAK at around 21,000 would probably not have enough power to operate the action.

    Glock got around this with the .380 ACP Model 28 by grinding off the barrel / slide locking surface over the chamber and making it a blow-back operated action.

    Might work on a KT 9mm too I suppose.  

    rc
     
  6. TxCajun

    TxCajun Administrator Staff Member Supporter

    Sep 7, 2004
    Texas
    I would only add that most if not all of the cheaper 9Mak ammo you see is steel-cased, a bad pick for KT pistols anyway.
     
  7. joje

    joje New Member

    213
    Nov 1, 2007
    interesting aboug the glock 380 - never knew glock deviced a blowback type pistol, but on the other hand isnt the p3at living evidence that its perfectly possible to make locked-breach design pistols chambered for cartridges originally intended for blowback designs?
     
  8. rcmodel

    rcmodel New Member

    Feb 6, 2005
    Eastern Kansas
    Yes it is.

    However, the barrel cam angle, slide mass, recoil spring strength, and a few other things determine what pressure / power level the action is designed to operate with.

    In the case of converting a 9mm to work with .380, or 9mm MAK, it would require converting it to a blow-back as Glock did, or a complete redesign of the barrel cam angle. (Lock delay)

    rc
     
  9. engineer88

    engineer88 New Member

    376
    Nov 26, 2007
    I think if Keltec made one more model, somewhere in between the size of the PF9 and P3AT and chambered it in 9x18 it would be the very next pistol I bought.  I think a lot of folks find the PF9 too big for pocket carry too (I don't know, I don't have one yet, but I read that a lot on forums), so I am pretty sure I am not the only one who would be buying.   :cool:

    That size would be the sweet spot if you ask me.  Cartridge would have a wee bit more pep too which is always nice.  There may not be a lot of SD rounds for 9x18 yet but the garden variety stuff is pretty close to on par with the fancy .380acp rounds out there.  

    It wouldn't make much since to put the 9x18 in PF9 to me unless you are trying to extend the pistols service life, but with the lower pressures I think something in between size wise would be fantastic.  I would be all over that and probably carry that sucker every day.  Heck I would probably buy two just because.   ;D