Sighting in 30-06
 

Just got my Marlin xl7 30-06 wednesday and put a Redfield 3-9x40 scope on it. Someone told me to sight it in at 25 yards and to zoom the scope at 5 to where I am shooting 1" groups above center. They said if I do this the scope will be sighted in at a few hundred yards when I zoom it in all the way. Any truth to this?

never heard of that. the point of impact should not change when you increase the power of the scope. after getting the rifle shooting at 25 or 50 yards, then sight it in at 100 yards. this should work unless you will be shooting longer ranges.

It's ok to get the gun on target at 25yds if it's not been bore sighted but I've never heard the rest either.I'd avoid any of these new and wondrous sighting methods.Go to the range and do it the olde fashioned way.It's the way that works!!!

What Bernie said. Just go to the range, get on paper @ 25 then move back to 100. For typical loads (150, 165) get it about 2.5-2.7 inches high at 100. That will make the best use of your MPBR.

Scopes made today are supposed to be designed so that the POI doesn't change as power ring is increased or decreased but not all of the scopes do.. The only way to actually check is by actually target practicing.Take the gun and mounted scope to the range, Once you have it where you want your liking, at 100 yards, than check you variable magnification throughout the entire power ring.. and see fir yourself if the zero changes as you change magnification..
Like I said most scopes made today won't change, but the odd one might in any brand make and model..
It all depends on how the lenses are arranged inside the scope..

Still only one way to know for sure;

25 - get on the paper (should be below the bullseye).

50 - don't waste ammo, still on paper ? (Hopefully, closer to bullseye)

100 - looking to shoot tight groups now............preferably in the bullseye (especially, if you have a BDC type reticle).

200, 300, 400, etc. - groups holding under MOA throughout !

Practice, practice, practice !!!