Has to be SBR papered because it is made from something originally a long gun.
All the bolt action and long range pistols you see are legally distinct starting out as bare receivers or legally handguns even though they are closer to rifles than handguns in reality.
For example you could have two identical AR pistols side by side, and one could be a felony unregistered NFA item because it was made from an AR rifle, while the other one was made from a receiver.
Even though they have all the exact same parts and look identical they are legally quite different.
Ruger for example came out with the Charger pistol. It is a 10/22 without a stock that is legally a handgun. You can readily go purchase one and it is legally no different than any other handgun.
Yet if you made your own identical Charger pistol from a 10/22 it would be illegal without NFA paperwork.
So most long range pistols you see that are basically short versions of long guns without a stock were manufactured as handguns from the start.
Rail Driver said:
If there's not enough gun to keep ahold of when you shoot it, you're likely to break fingers, wrist or other body parts in recoil. My M44 is a handful, and it hasn't been modified at all - to the point that if it's not properly shouldered, it can and has broken collarbones (just not mine). Your pseudo "Obrez" is going to kick harder than one of those AOW 12ga super shorty shotguns.
Actually many such short barreled rifle calibers have less recoil than you would think. The reason is they are cartridges designed to be fired from a rifle, and so the powder is made to make the most of a certain minimum average barrel length.
(In our society for example with the NFA, cartridge manufacturers know that rifles are going to have a barrel at least 16" long, and many calibers average longer than that. So they will design pressure curves that need that much length, but generate more overall power. They know this when designing the cartridge too, determining case capacity to generate the intended operating pressure in a certain barrel length range.)
So in a really short barrel they don't generate the pressure curve they do in a rifle, and blow a lot of unburned powder out the muzzle in the form of a giant fireball.
So they are loud and create massive fireballs, but all the powder burning outside the barrel is not creating pressure, imparting velocity to the bullet, nor creating recoil energy.
Performance wise the result is also that many really short barreled firearms in rifle calibers actually generate less power than the same size firearm would if it was chambered in one of the big handgun calibers instead. As the handgun cartridges are designed to reach maximum pressure in a much shorter barrel, and so are on average more powerful until you get to a certain barrel length.
And being more efficient they also don't generate a blinding fireball out of a bunch of wasted powder.
That is not to say they are pleasant, just not as bad as they might be expected with a really short barrel. A A 7.62x54R with only half of its powder burned before the projectile exits the muzzle for example is going to generate a lot less recoil.
Efficient rifle powders are designed to burn up to a peak pressure, then generate so much more power than a handgun by maintaining near that pressure for awhile before they begin to fall. They generate a lot more power than a pistol powder that spikes to its intended pressure and quickly drop, but they need a long barrel to do it in and generate that long powerful pressure curve. Putting them in a short barrel means they likely don't even reach their intended operating pressure, never mind maintain somewhere near it for awhile as intended.
Here is a video of a guy shooting a Mosin pistol with 7 inch barrel without even much grip to hang on to and as you can see it is quite manageable:
http://www.youtube.com/watch?v=rNFsUvh078I
Most of the powder is clearly being wasted minimizing recoil. If it was generating the power and recoil of a full size barrel it would be a lot harder to manage than that.
Now that said you could certainly develop some loads using pistol powders to operate within the SAAMI pressure limits of the cartridge that maximize velocity gain in the short barrel.
Those would generate both velocity and recoil that was closer to a reduced barrel length version of the full rifles, tailored to be efficient for the available barrel length. They would likewise be hard to manage and give the type of brutal recoil you are expecting.
