Re: 6mm-223 supressor
Any of the 223 cans can be opened up to run on the 6x45 , and they will actualy be a bit more effecient at reduction due to the more effecient bore to powder ratio of that round (awsome choice by the way)
BUT , also any of the 308 cans will also work well , yea the bore is a bit bigger and it looses some effeceincy their but the added volume more than makes up for it.
I'm sure that one of the smaller builders like Shark and SAS can make you a suppressor with the proper bore diameter