Re: 7mm ultra or firebird
I would agree with Dave on this one, go directly to a 3 groove Lilja. I have used these in my Wildcat rounds that have expansion ratios that make the 7mm RUM and Firebird look pretty tame and they have performed extremely well offering as much barrel life as is possible in these extreme rounds.
In my experience I have always found 4 groove barrels to run pretty tight for some reason. I have never seen this with the Lilja 3 groove. Well, they are tight for sure as they are built to true BR specs but they are not overly tight to cause pressure issues.
This may also be of interest to you, I recently hired Dan Lilja to build me three new 3 groove barrels for my family of wildcat rounds, they are the 257 1-7" 3 groove, 277 1-8" 3 groove and the 7mm 1-7" 3 groove. With some of the new 200 gr ULD RBBT bullets out there, if you want to really reach out and hammer something with a 7mm, you may want to look at this new barrel.
Dan is tooled up for them now and is offering this twist option to the public.
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