I've build several , the one my 308 wears full-time was built for a 300 win mag.
the outer tube is 1.625" OD , 1.485" ID that was bored from solid 316L SS bar. The OAL is 9.5" , the read end cap is also the blast chamber with the first baffle welded in place
followed by 9 , 60 deg cones spaced at .750".
It is heavy but it is quieter than any commercial 30 cal can I've heard , I've shot it on a 300 RUM with zero issue. Im tempted to shoot it on a 338 Lapua but the bore is to tight.