My sister is a nurse and when i used to inject she whould have me change the needle after i filled the syringe with whatever I was injecting. It may sound silly but a new neddle is sharper. Also on a quad injection place your hand on you thigh and with you thumb and forefinger stretch the skin out as much as you can for a cleaner injection ( and it won't hurt as bad).
it only hurts for a second! really though man it will get better with time and to tell you the truth i got to the point where i look forward to it. i know that sounds a little f*cked up but i just love the feeling know. I hate to tell you this though bro, if your using a 1" in the ass your probable not getting the gear deep enough into the muscle. you need at least a 1-1/2 to 1 3/4 to get it in, but a 1 " is fine for the leg. thats why it's called intramuscular.