copes is taking pre orders on 5.45 kits Id just buy one of those intead of a rommy or some other x39. the extra $75 you pay for the it is well worh getting the carrer bolt a nd 22 mm trunin that all match and work together. I got $50 each into my 55.45 bolts and carrriers alone. I have two kvar 5.56 bulgy bolts left and that is. there like gold to me as i havent seen any for sale for over a year or more with the spring loaded pin and large stem. Im going to do a 223 on a 5.45 bolt and trunion and see how well it works out and what tricks need to be done.