Best long range caliber

Waylon n ninja. I know whatcha mean. I got a leupold mk4 m1 tactical 4.5-14x50mm n it cost me $1300. Iv got it mountd on my M40 USMC rifle. Ninja, i had been dealin with tr for a bit, just didnt relize it. I got my quote today for a LR tactical with 22" stainless barrel n stainless fluted bolt with folding stock n before my silencer n new scope, its nearly $6,000. Im gonna reveiw n tweek a little more on it n place my order before i head back to afghanistan next week. I figure after everything, i will have right close to $10,000 in it, but i'll be ready for government zombie apoccolypes. Just gotta get a reloader n dies n get my 1000rds of .308 brass reloaded n reload supplies for my new toy. Thanks for bringing this subject up, now i done got reinterrsted in it n gonna finish what i started 5yrs ago.