10 mm kel tec sub 2000 conversion


December 10, 2009, 02:29 AM
Serious speculation wanted on converting a .40 smith keltec carbine to 10mm. The two problems I'd envision are the magwell either being too hard to convert or just not big enough, the other thing is it my need to have a heavy bolt to work. Making the bolt heavy might not be possible. Has anyone heard of any such conversion, or know how hard or easy it would be for a gunsmith to do?

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December 10, 2009, 12:32 PM
It would seem to me it would be nearly impossible for the reasons you mentioned.

The SUB2K is a 9mm platform, with 9mm size mag well.

In order to increase the mag well length another 1/8" to hold 10mm, the plastic grip would have to be cut, extended, and somehow melted back together.
I don't know of any way to do that.

Anyway, a blow-back operated 10mm and the additional chamber pressure over the .40 S&W doesn't sound like a good or safe idea to me.


December 11, 2009, 10:06 AM
I don't think the original design was meant to take those size cartridges or those pressures.

Kel-Tec has had many requests to make it in that caliber, and hasn't. I think they would've if they could've.

December 12, 2009, 06:09 PM
It might be cost prohibitive for them to do so, the .40 operates at 35,000 and the 10mm 37,000 and the .357 sig at 40,000 psi, so it's not like the you would have a catastrophic failure. And the inside of the magwell could be shaved out, a 10mm should not be longer than the whole magazine well only larger than its internal dimensions. Maybe I should just call a gunsmith. Thought people might have a little more precise knowledge, something a little more specific. Would like to find some exact dimensions of the magwell and it's relation to the feed ramp.

Marlin 45 carbine
December 12, 2009, 06:35 PM
one of my nephews has a kel-tec set up for S&W 5900 series mags, I've looked it over to determine suitably of shooting +P loads in it (before a call to the factory service tech assured it was fine to do so) and near as I can tell it would be a tight squeeze likely requireing at least some redesign of the reciever/bolt and hand grip/mag well.
btw his 9mm does indeed handle +P 124gr Rem Golden Sabre handloads without any hint of stress. and judgeing by the damage one of those does to stacked, wet and mud covered pieces of 2X4 when shot out of that 16" bbl I surely do not wish to suffer being shot by one. perfect expansion and remarkable damage to the wood.

December 16, 2009, 02:27 AM
Yeah I love the little things, especially for the price. The 9mm is practical for me to think about getting as is, but a 10mm I think would be devastating out of a carbine, a pistol/carbine combo as good as the .357, except this one you can fold up and put in your backpack.

December 16, 2009, 11:51 PM
The 10mm is just a hair over 1/8" longer than the 40 S&W. Assuming you can modify the magwell to accept a 10mm Glock mag then doing the swap MAY just take some work on a heavier recoil spring, heavier bolt, recut the chamber for the longer 10mm, etc. Not sure about an extractor, or if there is even enough room inside the gun to fit a 10mm lengthwise. Feedramp issues ? Sounds like you need to send a donor gun off to the machine shop and have it worked.

December 18, 2009, 02:01 PM
Oh yeah, this work I would leave to an experienced gunsmith, but right now it is a pipe dream, I have much more practical firearms priorities. And much, much, more important life priorities, but I've always been a huge 10mm fan, I currently have a colt model 357 and if I wanted a pistol caliber carbine with potency I'd just get a marlin 1894. I was really just looking to see if someone else had tried it, or gone to a gunsmith and was told it would be A. very cost prohibitive or B. pretty much impossible.

December 18, 2009, 09:16 PM
What he was trying to say is cost prohibitive given your current projected outlay of cash. If there is room inside the chamber, grip frame areas for a longer cartridge then it can be done. The 10mm is not that longer or more powerful than the 40 S&W.

Defense Minister
February 13, 2010, 04:56 PM
There is a reason Kel Tec warns against using aluminum cased ammo in the Sub 2000. I imagine that would apply to a 10MM conversion as well.

February 13, 2010, 05:37 PM
The gun has a blow-back action. (not locked-breech)
Pressure is still high when they start to open.

There have been reports of aluminum case ammo rupturing in blow-back operated sub-machineguns.


February 14, 2010, 04:00 PM
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Have I mentioned that I can get way more power out of a 1.13" 40sw 200 gr than I can out of a 1.3" 10mm 200 gr.?

That is because the 40 has a small pistol Boxer primer pocket and the 10mm has a Large pistol primer pocket.

Aside from antique balloon head cartridges, the 10mm is the weakest case in the world.

The blow back system works well in 380, as I can get 357 mag power levels in the Colt 1903 blowback but only 380 level loads in the Kel-Tec P3AT 380. That is because of case support.

Here I tried to do some blow back design calculations back in 2000:

I have since been burned with the blowback in the 10/22 conversion to 17M2.
I bought the weighted bolt handle, but still got the fried egg rim.
Good thing I was wearing safety glasses.

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