Originally Posted by
PhilR.
You aren't going to find a way. The parts look similar, but the makers of the tacticool .22's deliberately make the parts dissimilar in order to thwart people like you from cobbling a rifle together and then have dangerous things happen to themselves and others around them.
If you like to customize, you should consider getting a real AR and add a .22 conversion. You can customize the livin' stuff out of them. You could also get a regular AR lower and add a .22lr upper from Spikes or Tactical Solutions.
BTW - you didn't buy a Sig 552 in .22lr. since there is no such thing....