I started with Caverject Impulse, then Caverject injectionable powder. I used 30 ga, 1/2 inch syringes. The doc started me off at .5ml, which worked well for me, but gave me lots of aching, which after a few trials wasn't worth the results. I think that the drug in Caverject is the best acting, but also the most problematic, giving pain and aching during use. The Trimix has it, plus the other 2 drugs in it, and some men still have the same aching. Bimix doesn't ache or cause pain, feels the most natural, but takes larger amounts to accomplish the same thing that the Caverject does. It seems to be more varied in the response than Caverject does. Placement of the drug is critical, miss it by just a little bit and you end up with a chubby for the evening....
Getting personal here, but if your penis is overly large or especially thick, then the longer needle would make sense. .5ml isn't a really large dose of Caverject, so I'd try that. Double check your injection technique and try it again, with either 1/2 inch or 5/16 inch needle. If you are almost there now, then that should do the trick, so to speak...lol
A question: How are you handling the Caverject- any pain or aching during use?