Yes.
Yes
YES REMINGTON FIREBALL , OLD PRODUCTION. Also, a number of companies make AR pistols in .223.
The 250 is a double stack .45 ACP pistol. It has a DAO trigger, however.
One can make a pistol much larger than it needs to be, maybe even having an extra-long barrel would make a pistol larger, technically. I'll assume you mean the barrel diameter. Although it would seem that a .380 and .38 would have the same barrel diameter, namely, 38/100th of an inch, that is not usually very accurate. The .380 ACP has an actual barrel diameter of about .35 caliber, or 35/100th of an inch. The .38 Special has a barrel diameter of .357 caliber, or 35.7/100th of an inch. So the .38 Special has an ever so slightly larger diameter.
It would help if you gave the make, caliber, and condition of the pistol when you asked this question. Without that it all guess work.
The Benjamin 250 is one of three pistols that make up the 250 line of air guns. Here is how they break down: 250 is a .175 BB pistol 252 is a .22 caliber pellet pistol 257 is a .177 caliber pistol. The problem is finding .175 BB's today most all BB are .177 caliber. I've heard that BB are still .175 only the caliber of the barrel has moved up to .177 to accommodate pellets. I suggest you just try one.
Yes- but not very common. There is an automatic pistol caliber known as the .38 Super, which does not interchange with the .38 Special revolver cartridge. There have been a small number of target pistols built to shoot .38 Special Wadcutter target ammo. And there is at least one auto pistol made in caliber .357 Magnum (revolver cartridge). However, revolver ammo is rimmed, and auto pistol ammo is rimless- there are usually feeding problems when an auto pistol is made for revolver ammo.
No
Browning never "made" a 45. They sold the SIG with their name on it. Similar to their 380 which was made by Berreta.
Not enough information to even make a guess. You told us the maker- how about caliber, model, condition?
Nothing. S&W did not make this.
9mm Makarov is the caliber of the pistol. To answer your question, we need the make and model of tthe pistol. There are some pistols that do not have a hi cap mag, and not all mags work in all pistols.