Swaddle?

My 12 week is is having issues with the swaddle sacks lately. He likes to suck on his hands, but doesn't have complete muscle control yet so he can't always keep his hands in there, and then gets mad. Sometimes if I swaddle him in the sack I'll get frustrated and wiggle his hands out so he can suck on them or he'll knock out his pacifier, and then get even more frustrated. I can't figure out his pattern. Sometimes he sleeps wonderfully in the swaddle sometimes he only sleeps for an hour or two, or sometimes he sleeps great completely unswaddled. He is not a good Napper and usually wakes up after a half hour or so, again I've tried both swaddling arms out, arms in, or with no swaddle at all. Any advice? Should I try a different products other than the swaddle sack? I don't know if it's better to leave his arms in even though sometimes he hates it but then his startle reflex doesn't wake him up, or to leave his arms out since he fights it but then his startle reflex kicks in...