I want to get a 9mm carbine (995TS).
A little off topic here but what's the consensus on using one for a SHTF weapon?
I like the fact that I'd have ammo compatibility with my handgun (9mm also), but I'm wondering how practical it would really be.
As noted, in the Old West the manufactures produced their longarms and pistols in the same calibers for just that reason. I'm told some Cowboy Action shooters buy their replica Peacemakers and replica Winchesters in identical calibers, usually .38 Special or .45 Long Colt, for that reason too. .45 ACP is the round of choice for the new Roaring '20s Action Shooting I've been hearing about. The pistols of choice seem to be M1911s, and the longarms Auto-Ordnance's semi-auto-only Thompsons. Not having to worry about which round goes in which gun is a load off your mind.
Personally, I like the idea of compatible ammo for SHTF defensive weapons quite a lot. Operationally, however, you only have two choices in the 'universal cartridges': 9x19 mm Parabellum; and .45 ACP. Of the two, much as it hurts to say it, 9mm is the better choice.
Don't get me wrong. I much prefer the .45 ACP to 9mm Luger. It hits harder and makes bigger holes. It's been battle-proven in every war and brushfire conflict the United States has been in since 1917. You shoot someone with it and if you hit them in the head or the chest, they go down and stay down. However, the deciding factor in this race is weapons choice.
On the pistol side, it's a wash. Everyone and their uncle makes pistols in both calibers. In the case of the .45 ACP, you can even obtain .45 ACP revolvers, notably the S&W Model 25, the 1917 'substitute standard' US military revolvers by Colt and S&W in both original and Classic models, and the 'shaved' Mark VI Webley modified to take .45 ACP instead of .455 British. You can't say that about the 9mm Luger cartridge.
But when you come to longarms, the 9x19 pulls ahead and stays there.
On the .45 ACP side, you have the Hi-Point Model 4595 (if you can find one), the Auto-Ordnance semi-auto-only Thompsons, their semi-auto-only M3 Grease Gun, the absurd-looking and not very good shooting Cobray M-11, and not much else. None of these except the Model 4595 can really be accessorized to suit your needs.
Just going off the top of my head here, on the 9mm side you have the Hi-Point Model 995, the Beretta CX-4 Storm, the HK-94 (the semi-auto-only civilianized version of the MP-5 for the US market, a very elegant gun; I wish I could afford one because it's essentially a 9mm CETME), a couple of Kel-tecs, a Cobray long-barreled semi-auto version of the old M-10, and the Sterling semi-auto carbine. Of these, the Hi-Point, the Beretta and the HK can be customized with off the shelf aftermarket accessories.
For that reason, I'd have to say that going with a 9mm carbine and a 9mm pistol, provided both will reliably shoot hollowpoints, is an option to consider for SHTF; perhaps even a good option. Choose whatever 9mm pistol you prefer. For the carbine, I'd go with the Model 995. They are simple, utterly reliable and affordable; a Model 995 will cost you less than your 9mm sidearm!
Gun Tests gave the Hi-Point Model 995 and Model 4095 carbines their highest grade when it tested them. The verdict boiled down to, "They're ugly as sin but they always work, they shoot accurately, and you can't hardly break them." Those are virtues in a survival gun.
Just bear in mind that a
pistol cartridge isn't a
rifle cartridge, or even an intermediate-power assault rifle cartridge. 100 yards is going to be a reach for you for a one-shot kill, even if you scope the carbine. In practice, 50 yards will be your effective range. Can you live with this fact, or not?
In the end, that may be the deciding factor on whether you go with a one cartridge solution for your sidearm and your longarm for SHTF use. You'll have to decide this one for yourself.