Your character's level has no effect on Crucible during a normal (not Iron Banner) match, neither does your weapon or armour's attack or defence ratings respectively. As for getting killed by hand cannons a lot, there have been some weapon re-balances since you left. Auto rifles in particular are considerably weaker and pulse rifles are now a much more viable option. I'd suggest that trying out a few new weapons or weapon classes might be advantageous. Apart from anything else, you are out of practice at playing Destiny. Of course you won't be doing as well! With a bit more playing I'm sure you'll get up to speed again, if you want.