Welcome- how about stopping over by the intro section, and introduce yourself to us-
Now, take a DEEP breath- remember punctuation is our friend....
Trying to sort out your question(s)
First, a "necked"cartridge has a larger body that tapers quickly to a smaller bullet. Not used in a LOT of handguns other than single shot pistols, it is mainly a rifle cartridge, and is a means of increasing pressures, and from that, increasing the speed of the bullet in flight. Do a Google image search for 30-06 cartridge. Necked down to .22 may mean a cartridge that is usually .35 or .30 caliber is squeezed down further, to .22 cal.
Pros and Cons of using...... Sorry, you lost me there. Using for WHAT? Hunting, Bullseye type matches, Bowling Pin shoots, self defense, a paperweight... Most 1911s are caliber .45 ACP- have seen a few in other calibers like 9mm, 38 Super, and .38 AMU- but a .357 does not jump out at me. .357 Magnum is typically a revolver, ot an auto pistol. There is no 275 Gr .357, nor a 300 grain. Those are rather heavy bullets even for a .45 ACP.
Could we take another run at this, and explain what it is you wish to accomplish? PS- While I CAN be sarcastic at times- this really is not one of those times. We'd like to help, but question needs unmuddling first.