I don't see why it wouldn't work, you may have to tinker with the magazine some but that shouldn't be a problem. As far as the BLR and BAR I don't think the feeding problem would be as big of an issue because you don't have pressure curves and bolt speed and all the other things associated with semi-auto feeding. The other issue would be the forearm and barrel bands but once again not a real problem just a modification, and maybe you could use the ones for the 450, I don't know. I think it is probably a workable project, I don't know about the cost but then again sometimes the cost is not so much of an issue when it is something we really want. Let us know how it turns out.