Yes, any bullet of any caliber can be lethal.
45
If you are talking about a PCP (PreCharged Pneumatic) rifle. With a .45 caliber pellet, then "Yes" It can. I don't believe there is a 40 Caliber pellet gun.
.45 caliber
It's main purpose is to fire a .45 caliber bullet which, in turn, will kill or wound any one who happens to be its' line of fire.
No. The AK-47 fires the 7.62x39mm round, which is of the .30 caliber, smaller than the .45 caliber.
The .45 caliber is bigger in diameter. If you mean weight. The .45 caliber is generally heavier. However there are some lightweight .45 caliber bullets that are lighter than .357 caliber bullets. Generally speaking .45 caliber bullets weigh between 180 - 230 grains. While .357 caliber bullets generally weigh between 158 - 180 grains. If you are talking about diameter, the .357 caliber bullets are approximately 0.357 inches in diameter. The .45 caliber is approximately 0.450 inches in diameter. Again, using this measure, the .45 caliber is the larger bullet.
a .45 caliber.
What is the use of grip safety on 45 caliber pistol?
Noop. an M16 fires a 5.56mm (or .223 caliber) bullet. A .45 caliber shoots a bullet that is ~11.43mm.
Probably. It would likely refer to a handgun that fires a .45 caliber ACP, or .45 GAP or an older .45 caliber revolver round.
Depends on which 45 and which 44 chambering you are talking about the load