Here's my two cents on this. Well............yes this started out as $.02c, however after about 1000 words it's a bit more than $.02c. YES I have had my zero knocked off and it cost me a deer while hunting in Vermont. I was shooting a Remington 742 and at that time what was popular was the "see-through" mounts. The scope was mounted high over the top of the receiver and there was a hole underneath the scope so that one could see the sights if needed. It was a handy set up because close up the iron sights were, there if hunting over a field or low light one had the scope. I had just settled into a stand on the side of a field when the rifle just slid slightly, hit a rock in the stone wall that was part of the ground blind, and.....that's all that happened a slight bump. A deer came out close, like 60 yards, it was an easy shot but I missed!! Long story short the scope had been knocked out of zero by that littler jolt. I believe that it was due to the scope being mounted so high it was an easy task to knock the rings out of adjustment, and not the scope. SO....yes that was time when I missed a deer due to the scope being knocked out of adjustment.
For "me" personally I always hunt with "at least" two rifles that are both sighted in for the same point of impact for the area where we a hunting. I use Warne bases with Warne detachable rings. I know that there will be some people with different thoughts about Warne rings and bases, but these work for me. With that said I always will pack an extra scope that I have previously sighted in for the primary gun that I am going to be hunting with. Most of the rifles that I do hunt with are Ruger 77's with the built in/integral scope base, so the base never moves and the rings/scope can easily be removed and another scope in Ruger rings can easily be installed. Many years ago I did a caribou hunt in central Canada. We flew 360 miles out of a small town called Chefferville, and Chefferville was about 1500 miles north of Montreal on accessible by plane or train. There wasn't a local WalMart or gun store around. We were allowed to carry 65 pounds (?) to include all of our gear (including clothes and sleeping bag) along with our ammunition and rifle; it was like $10 a pound for anything over the 65 pound limit. I was hunting with a Ruger 77 in 300 WinMag, scoped, and without any iron sights. I did however take another scope mounted in Ruger rings as part of my 65 pound limit. On the first day of the hunt I slipped on some mud/moss in the tundra, the rifle went flying and it took a big hit on a rock, the scope took a big dent in the tube and a crack in the lens. I installed the extra scope, checked the zero that had not changed and had a successful hunt. And........I can attest that out to 300 yards the zero from one scope to the other does not change.
I am a believer in Leupold scopes, again I am sure there are opinions about Leupolds; however, they are my choice of scopes. In hunting conditions, I DON"T CARE what one has for a "quality" scope, there are times when no matter what one is carrying, under the right conditions IT WILL/CAN break. With that said and without the option of taking along two rifles I recommend having an additional scope, that is mounted in a scope base and rings that afford the ability to change one scope out for another. This principle is the same for me carrying an extra rifle, in case my primary hunting rifle gets broken; as in stock or any kind of a mechanical break down. In the past I have loaned a rifle to another hunter because theirs fell out of a tree stand and the scope and the stock were both broken and rendered useless.
For the rifle that you are considering to build, I would strongly suggest building a .270 Winchester Short Magnum instead of the 7-08. You can do the build on a short-action, and you will have all the horsepower to hurl the light bullets at the high velocities you are trying to achieve; and, with the .277 caliber the BCs ought to be a little higher than the .284 caliber. If you really are looking for long range, you could build a .270 WSM with a fast twist and shoot the heavier, high BC bullets that are popular today. If you really are insistent/stuck/determined with the .284 caliber, I would take a serious look at the .280 Ackley Improved. I know "long-action", but in my opinion not enough between the long and short action to make a difference when one considers the potential benefits over the 7mm-08. Again my opinion, this is my $.02c worth, hope that I didn't start any fights here
"with my opinions!!!"
Good luck with your build and with your hunt.
