I love pecs man. So easy to see, aspirate, etc. Really you want to try to go center of the pec. For me (and most people) that tends to be about 2" from the nipple left or right depending on what pec and about 1 and 3/4" up. So if it’s your left pec and you are looking down at your pec, you will go 2" to the right, then 1 and 3/4" up, like toward your collar bone. The pec takes a little time to get used to so don’t go balls out and hit it with 1.5ml lol. Start at about .5ml and work your way up. It will be sore like a chest day type of sore but you get used to it quick. I have used 1" 25g pins completely buried with no issue and 1.5ml without leakage. Also, theres some nerves in there that aren’t so pleasant if you hit them. Go easy and remember not to flex the muscle. If you need more meat to pin, you can cross your arm to sort of puff up the pec without flexing.