Sir, I have two long range rifles. One is a .30-.338 built on a pre 1964 winchester action, and a .300 WSM built on a Nesika benchrest action. Both rifles cost around $3500 to build because turning an inch group into a half inch group can double the cost of a rifle. In 19 years of hunting the beanfields of North Carolina, My longest shot was 450 yards ranged with a Leica rangefinder off a solid rest. My thoughts are this:
First, how accurate is the rifle. An inch at a hundred is four at four hundred and the vitals of a deer can be about an eight inch circle. Four inches off center before human error is factored in is a wounded deer. Unless you find a load that will shoot a half inch or better, 400 yards is pushing the envelope.
Second, the issue of the bullet performing properly at the end lf the journey to do the job. .308 velocity at 400 yards is .30-.30 velocity and bullets with thin jackets designed to expand in that range like Nosler Ballistic Tips (try 165's) will deliver the most energy to target. Big critters, if you would be comfortable with the energy of a .30 - .30 with the shot placement you have. OK.
Last, my .30 - .338 was the old fashioned solution for getting more range out of a .30-06 which entailed taking a chamber reamer to an "06". Back when the Holland and Hollands were the only magnums in town, the Marine Corps were using the .30 - .338 in the 1000 yard Wimbledon Cup. You can sit with a gunsmith and explore the option of converting your rifle to a .300 WSM which entails recutting the chamber, and opening up the bolt face and magazine. My .300 WSM is very accurate has a lot of power. I believe the lightweight mountain rifles the big guys are marketing the caliber in do not do it the justice that a long range target style rifle does.
PS. talking about this long range stuff, I shot a buck on Sunday at 20 yards with a bow. He went 20 yards shot through the heart and fell down dead!
