If you don't like needles...

[Corpsman]

And the pain afterwards was so bad I could barely move the arm because of the soreness.

What the hell were they doing giving a kid injections in their arms? The muscle mass isn't dense enough, of course it hurt like hell! I got all mine in the butt until I was at least 10 or 12.

That's just standard procedure. At least it was when I was a kid. Maybe it's to speed up the process, or to avoid accusations of inappropriate touching, though that shouldn't have been as much of a concern in the seventies.

We generally avoid butt shots because of the sciatic nerve. Your chances of hitting it are pretty low, but oh boy if you do... The only reason you would get a butt shot is if the med dosage is larger than your arm or leg can handle. (Such as a penicillin shot.) For little kids, the deltoid muscle is not fully developed yet, so all shots will generally go in the leg.