As for short barreled autos not being accurate that is just mind boggling that someone would still think this, i have seen and own some semi-autos that will out shoot any single shot on the planet, sorry but it is a fact.
I really hope you are just trying to make case using an intense over statement.
If you really believe that you own and or others own semi-auto handguns that can out-shoot (I assume you mean as accurate or more accurate) single-shot handguns, then I do not know what to think.
Hopefully, you are only comparing straight-wall cartridges only.
Please, tell me what group size your straight-wall case semi-autos can do for 5-shot groups consistently @ 100 yards?
If I was a betting man, my MOA Maximum (straight-wall cartridge) will wipe your semi-autos out. Whether you want it at 100, 200, 300, or 400 yards, or all of the above, it is fine with me.
Even with a prototype FA single-shot pistol (Straight-wall case)I hit steel at 500 yards 4 out 5 times with a gun I had never shot before, it had a heavy 3 pound trigger, and we had run out of scope adjustment for wind and elevation on the scope so we were holding off to boot.
I have a very accurate 1911, but on its best day it doesn't stand a chance of touching the two single-shot pistols I am talking about.
If, you are talking about any single-shot pistol in any cartridge (bottle-neck cartridge) then, if you can shoot your semi-auto better than .1 or 1/10th of an inch group at 100 yards or under 1.5 inches at 600 yards, then I got to see that gun shoot.