Not really IMO. I got some really thick deca through an insulin pin once when I had to. It just takes FOREVER to load and you have to PUSH like hell on the plunger. The only problem I'd see would be with winny, since it may clog if you have Jurox or something.
3cc's in rear delt? no way... 1cc max... I injected 3cc into delts, each on eod... And ended up with big pockets of gear in each delt about the size of a baseball... I wouldnt do it
I shoot 2.5 in my delts eod with no probs. Just make sure you go in deep so you don't release it above the muscle and end up with a big ass lump of wasted gear.