I don't buy that 1 m.o.a. at 100 yards always equals 1 m.o.a. at 700 or 800 yards (or even 300 or 400 yards). Little things that don't make much difference at 100 yards begin to add up when you stretch the distance.
How consistent is your velocity? How good is the bullet? .30-.378 kicks a lot; is recoil an issue? How consistent is your cheek weld? Is your trigger pull straight back? Are you settling in on the bags the same each time (or applying the same pressure to a bipod)? Any runout in your bullets?
The above factors are pretty forgiving at 100 yards. They start to make a difference as you shoot farther out. And this all assumes there's no significant wind.
I'm not trying to bust your chops or bring you down or anything. Just wanted to get across if your intent is to shoot game at 750 yards, don't worry or get fired up over what your rifle's doing at 100 yards. Concern yourself with what it's doing at 750.
You need to find a place suitable to shoot 750 yards and try it out if you intend to hunt at those ranges. That should be your deciding factor. Once you pass 400 yards I wouldn't shoot at game at more than what I have practiced at.
I would say you should be more in the 0.5 MOA range from 100-300 yards before going for any game at long range. At least try them at 300 yards and see what kind of groups you get there.
I start at 100yards, then if a load seems promising (well under moa) I move out further, but the load needs to be chronoed. I used to just try to get my groups to 1/2moa or better at 100 but after shooting over a chrono and seeing up to 40fps variance in my load my eyes were opened quite a bit. At 1000yards my groups seemed to have a lot of verticle stringing...as to be expected. I learned that tight groups up close are only half the eqaution. Your load needs to be as accurate and consistant as possible.
A load that is bad at 100yds is, for the most part, going to be bad at long range (some argue the whole stabilization thing but if I encountered that I think I'd still be nervous). All a 100yd group tells you is whether it is worth investigating at long range. You can never shoot at 100yds at assume you're good at extended ranges.
My elk rifle is good to about 900 yds on elk though I could get a mile out of it on targets. I shot it various distances out to 900 yds before I ever took it afield.
Everyone seems to get hung up on group size when talking about long range hunting. In my opinion group size only comes into play when tuning the rifle and load and ones skills. Once you have that the important thing is can you hit what you shoot at? Using your number 750 yards can you with a cold barrel shoot cross canyon and put the bullet into a 10 inch kill zone on a elk with the first shot. There are a kazillion variables that influence that shot.
You see nice groups all the time. The problem lies in that the groups are not at point of aim. If you can shoot a 1 inch group or less at 100 yards and the group is surrounding where you aimed then in my opinion you and the rifle are ready to stretch it out and find your limit and the quality of the load your using.
In agreement with other posts, what your rilfe does at 100 yds doesn't necessarily reflect what it will do at 750 or farther. There are a number of things that could affect that, probably the biggest being your load consistancy. Once you start getting out to 700 yards and farther, inconsistancies in your load will start showing where they wont show at closer distances. Mainly talking about velocity here.
Groups are only a measure of your rifle's potential to be repeatable when it comes to hunting. BR shooters are allowed sighters. In a hunting situation that is usually not the case. You need to be able to make a good hit on the first shot.
To more directly answer your question, I would be looking for about .5 MOA or better @ 100 yds to show potential out to 750, depending on your target size, i.e., elk or deer, etc. If my target is going to be deer I want to be very consistantly hitting about a 10" ring at 750, ON THE FIRST SHOT, which is a little over MOA. if your rifle is shooting .5 MOA @ 100 yds, other facters will probably push that out a little at 750, plus making it the first shot accuracy vs group precision. Load consistancy and wind are going to be your biggest nemesis.
Where to start? Once your rifle is sighted in, get out to at least 200 yds and farther for load development. 300-400 yds is where you start to see your load's consistancy. Pay more attention to the verticle distance vs the horizontal for the quality of your load. Once you think you have a good load and your rifle is properly set up and tuned, then spend most of your time shooting at the distances you want to shoot game at. Use the same target for your first shots. The first shot is what it's all about. This is where you'll learn a lot about wind and what your limitations are.
My vertical grouping is spectacular, I am sure I am holding that under 1/2" out of 10 younds I have shot. My hoizontal group seems to be a little worse, but a touch under an inch. What are typical causes for horizontal errors?
Your horizontal spread could be any number or combination of things including wind, rifle, scope, shooter all of which can also affect the verticle spread. Make sure your action is clean and snug in the bed of the stock and your rings and bases are also snug and torqued properly. Practice your basic marksmanship skills and fine tune your load. Once you know the rifle, scope and yourself are squared away you'll be able to tune your load better and learn how to deal with the wind. Move out to 200 yds or better yet, 300-400 yds. 100 yds just isn't going to tell you much.
Parallax may be the problem. Does your scope have parallax adjustment and do you know how to use it. While you are at it did you adjust the eyepiece of the scope to fit your personal vision requirements.
Second place to look is the pressure point. It is standard and customary for Wby to use a pressure point near the end of the forearm. I do not know for sure that it is true of your particular rifle but if that pressure point is not just exactly correct the barrel will shift as it heats up. Do not take out the pressure point unless you are willing to live with the results which may be either good or bad
Well I just reminded myself. Shooting too fast will cause a Wby to spray bullet like a skunk in a cat fight. You should be waiting about 10 minutes between shots.
I have been a huge advocate of group size for LR hunting. I still am........ to a point. I want a 1/2 MOA or less rifle/load at 300 yards. That doesn't mean it shot a small group ONCE....I mean every time you go to the range.....REPEATABLE!!!! Now I know the gun will shoot where I point it. Now, you need to know precisely what your velocity, BC, and scope height are. Now, the things that change every day.....temp, elevation, is your ammo hot or cold (do you have it sitting on the heater vent in your truck, or is it in your cold chamber outside where it is 10 below ...some powders are more prone to changes)....ect.... What was 3000 fps this summer will almost certainly be less in November.....check it with the temps as near as possable as when you plan on hunting. I start with a 300 yard zero (5 shots, each taken at least 10 min apart...ie..a cold boar zero) and dial up from there, but you need to be precisly zeroed.....not kinda sorta maybe!!!! If you are going to hunt with a bipod, then zero with the bipod on the gun. Some of the guns that are not free floated will change POI when you install/uninstall it. Practice, practice, practice....at very extended ranges. What I am saying is if you dial up for a 700 yard shot on a dear/elk/bear/terrorist.....whatever.....you need to know that that is where it is going to hit. A nice three inch 5 shot group that misses by 15 inches at 700 yards does you no good!!!! So much for group size.
How are you going to compensate for the distance....dial up, a multiple dot reticle.....? On my scope is taped the following info: Dial up chart from 300 to 1500 yards in 25 yard increments. I realy don't need them to be be every 25 yards for the first 700 yards...50 might do, but they should be 10 yards apart when you get past 1000 yards. A wind chart in 100 yard increments from 300 to 1500 yards for 5, 10 ,15, 20, 25, and 30 mph wind speeds. I use a NF 8-32 NSX with the NP-R2 reticle. I have a chart with the hold overs with the scope set at 22 power (2 moa hash marks) 17.5 power (3 moa hash marks) and 11 power (4 moa hash marks). When you dial up 20 MOA/inches on your turret, does the scope actualy move 20. Or does it move 18....or 22....or worse yet 18 one time and 22 the next. When I set up my program to make the charts,I use the elevation where I hunt, and I make an educated gues as to the environmental perameters. MAKE SURE YOU KNOW!!!. When you strech the distance WAAAYYYY out there, EVERYTHING MATTERS!!!!!!!
Now, (and this is my biggest fault) get your *** off of the bench and shoot in field positions!!!!! I spend 90 % of my hunting time in my shack where I use my bench equipment, but I truly feel ill equiped if I need to shoot elsewhere.
I guess what I am saying is that it is that first shot that counts.
I guess the reason I am changing my tune a little bit as of late is because I have some of my friends whos' guns I have developed loads for, and most are very good grouping guns, complain because they are missing at long range. Hitting high or low. 90 % of the problem is that the gun is not zeroed properly, thier chrono data is off a little, scope/rifle cant, or they simply didn't shoot the gun...AT ALL.....NO PRACTICE WHAT SO EVER!!!!ect......or a combination. And they call me 3/4 of the way through season!!!!