I recently purchased a 3.5x10x50 Pentax Gameseeker with the precision plex recticle for my Winchester m 70 in the 300wsm caliber. I am wondering what range would be best to zero the top line at (100 or 200 yards)? I will be shooting 180gr Winchester XP3s.

Can't decide? Use 150 Yd.

The scope instructions should tell you what the ballistics range set up is. I know the Burris scope with that type of reticle is set up for zero at 200 for the short magnums.

Welcome to the forum TRAVIS C.. Rules are simple, be nice and join in.

If this is one of the balistic plex scopes that give you different marks for 100, 200... yards then there should be some directions that came with the scope for various cartridge/bullet velocity combo's.

If not then my preference is to sight in a rifle in that velocity class three inchs high at a hundred yards. I'll then shoot it out to the limits of my ability to see where it hits at 100 to 500 yards. This has worked with most flat shooting guns in the 270, 280, 30 and 32 calibers that I shoot.

More often than not you will shoot at 100 yards and adjust your poi to be 1" high. That will put you on the + at 200 yards with a high performance load. If you have the luxury of a 200 yard range, zero at 200. You should still shoot at 50, 100, 250 and 300 yards to understand how your gun/load is performing.

Look up 'Maximum Point blank Zero' and use that. :)