wow....this has already been said but....you don't know the length of your pins????!!!!!???!!!!
c'mon bro.......1 1/2 " for glutes and 1" for quads and delts.
this isn't rocket science. swab with alcohol, landmark your site, penetrate deep within the muscle, aspirate, inject sloooooowwwlly and massage the area after.
www.spotinjections.com might help a bit.