[SUNDSVALL]

Hi,

I have read various threads regarding defensive caliber choice for handguns.

My question is, How does the 16.5" barrels of the Beretta CX4 Storm, Kel-Tec Sub2000 and Hi-Point carbines change the equation when selecting caliber? (9mm, .40 S&W and .45 ACP rounds)

(The Kel-tec only comes in .40 and 9mm, but the other two manufacturers make carbines in all three calibers.)

For instance, the Kel-tec claims that the Sub2000 in 9mm has the energy of a .357 magnum at the muzzle, a 9mm @ 100 yards, and .380 at 200 yards.

There is no data available for .40 and .45.

Does the extra barrel length increase stopping power, and allow for the selection of a smaller cartridge while still retaining the stopping power of the larger cartridge?

Thanks!

[Mas Ayoob]

Sundsvall, it's been years since I chronographed those calibers out of carbines. Working from distant memory, the 9mm standard velocity ammo hit +P/+P+ or .38 Super velocity levels out of the Ruger PC9 and HK94 carbines; standard pressure .40 hit full power 10mm velocity levels out of PC40 carbine; and the standard pressure 185 grain and 230 grain .45 ACP hit +P or better out of an Auto Ordnance Thompson. However, a load optimized to burn all its powder from a short pistol barrel might actually result in reduced velocity out of a 16.5" barrel due to friction drag. Bear in mind also that a bullet going faster than its design parameters can expand or break up too early in the wound path, sacrificing penetration.

The big advantages of the pistol caliber carbine in home defense seem to be greater confidence and ease of employment in the hands of less-dedicated shooters, and improved speed of center hit potential for skilled and less-skilled alike. It would be a good idea to do your own chrono testing with the guns/loads you choose.

best wishes,
Mas

[SUNDSVALL]

So how can you tell which cartidge will burn its powder slower?

Can we discern this from the cartridge designation? (9mm vs 9mm +P, .45ACP vs .45 ACP+P)

Or, is it a difference between brands?

[Mas Ayoob]

Night shooting with a pistol, something we should all be doing anyway, can offer a clue. The more muzzle flash we get (undesirable), the more powder we know has not been completely burnt in the shorter barrel and can be adding more velocity in the longer one.

That's just a rule of thumb, though. You really have to chronograph the individual load to be sure. Most loads will be faster out of a carbine barrel than a pistol barrel.

best.
Mas