Short of going to the lowest common denominator and getting the 2 pack from amazon for $8, where do we get quality thread adapters to use a .30 cal can on a .223/5.56? Silencer Central sells some that are ~$30, so does Brownell's. Is there any reason to splurge on these? Also, should I put one on each gun? Or screw it into the back of the can and leave each gun with a 1/2x28 cap?