just come in from gun room working on .260 rem. wilson barrel. bought barrel last spring on sale, just now putting it on m5 upper. after reading 98's experience with this barrel i had .081 drill bits ready. happy to say that someone at wilson must read this forum. the port in my barrel was .081 already, didn't have to drill it.brownells bolt headspaced correctly, may get it put together next couple of nights.