Still Swaddled

It's official. Ryan cannot sleep without being swaddled. He has been "sleeping through the night" for quite some time now...unless you factor in the number of times we go into his room to re-swaddle him. Sometimes it's once, sometimes it's three times. It's not a big deal, it only takes a second. But I keep wondering when he will grow out of it. He has a habit of incessantly scratching his head and rubbing his eyes when he is tired; that is the main cue that he is ready to sleep. But even though we trim his nails every other day, he inevitably ends up scratching his head and leaving marks. I wish he wouldn't do this and wonder when he will grow out of it; I hate to see all of those little scratches on his head! Anyway, when he breaks out of his swaddle during the night, he goes for the head scratching and usually can't put himself back down unless we reswaddle him. When we do, he is right back to sleep. No crying or shenanigans. I know that we are very fortunate to be getting as much sleep as we do with a 4 month old baby. I cannot complain about that. He is a dream sleeper as long as he is "contained"!! Great naps and 12-13 hours each night. But when will he be able to sleep without a swaddle??(he is outgrowing his favorite one!) It is a sleep sack with a removable velcro band that goes around his arms. We've tried the swaddle blankets, but they don't keep him swaddled for more than a couple of hours. We've tried sleepers with the built in mitts that go over his hands, but he still flails about and keeps himself awake doing so. The easiest thing is just keeping him swaddled as tightly as we can. I know that his nervous system is still developing which is causing him to have little control over his arms. I guess we will periodically try to wean him from it as he seems ready. A friend suggested trying to keep one arm in and one arm out one night for a gradual transition, but he just fussed when I was soothing him to sleep which is very unusual. Once I put both arms in the swaddle he was asleep in seconds! My big question is, will he just grow out of this or will he have to "learn" how to soothe himself with his arms free? So many parents that I talk to said their babies just transitioned without any issues; like they could take it or leave it. But we rely on it! If anyone has any good advice or info, please share!