Thank you, but other problem is that the hens don't let the rooster mate them, its funny though.
Well, if they won't let a small rooster mate, they won't let a large one either. If a hen really doesn't want to mate, she simply won't move her tail feathers, and there's nothing the rooster can do about it. Is it perhaps more a case of him grabbing on too far back so they only think they're being attacked? It's also possible that they're just far too young for it.
Despite the complaining, chasing and catching, and the dim view people take of it, most normal matings aren't actually forcible, it's just that the males are rude, clumsy, rough, and the hens resigned to it. They're courtesy matings. I have only ever seen a few hens outright refuse to mate, and trust me, physically there is nothing the rooster can do about it if she won't move into position.
I'd pay more heed to why your females don't want to mate with him; there is a chance it's just due to social breakdown or breed or individual tendencies, but also a chance it's due to something being very wrong with him. A rooster who treats hens well is almost never short of a willing mate unless something's very off...
As for AI, it causes quite a few problems when used as a preferred or common alternative to normal matings rather than under emergency or utterly necessary circumstances, I don't believe it should be done for the fun of it or just as a method of 'normal' breeding without a serious need, i.e. very rare genetics needing to be preserved. Confusing their sexual instincts is one source of much social disease among them.
Best wishes.