Ordered my Burris XTR II 4-20x50. By far the most expensive scope I've ever bought but I think it'll be worth it. I'll be running Talley Tactical rings w/a 20MOA Talley base on my 20" Remmy .308 heavy barrel (SPS Tact.) in a Magpul Hunter stock. I'll be shooting game from 100 to ~350yds. Targets from 100 to <1,000yds. My gun likes the A-Max 168gr but haven't tried the 178gr but will soon. I'm new to the long range game & not very well versed in it. Should I zero @ 100yds. so I only have to dial up? If I zero @ 100yds, will I be good to 1,000 w/the 20 MOA base?

The Scope has 90 MOA of elevation adjustment so you will have around +\- 45 MOA of elevation (depending on how much elevation adjustment it takes to zero) available to dial. This will get you to 1000 yards even without the 20 MOA base.

As far as what yardage you decide to zero the rifle, it will have no impact on the maximum distance you will be able to dial.

You wont be disapointed, that what I'm running on my heavy barreled 6mm Rem. Farthest I've taken it so far is 415yds. I need to get out to FJG's class and stretch it out a lil further....

It's a mil reticle. See if I have this correct:
It has 90moa adjustment which equals ~25mils (90 divided by 3.6= 25)
Half of that for drop so 12.5mils
It'll take ~10.9-11.2mils to get to 1,000yds w/178gr A-Max
I think I'll go with the 20moa base just to be safe
Is all that correct? Thanks.

Say you need 30 MOA to get to 1K. 90 MOA available internally. Zero MOA base puts you in the middle at 45 moa up and down (half of 90). Add a 20 MOA base, and now you have 25 MOA available down (45 moa minus 20 moa base) and 65 MOA up. Either way, you have plenty to 1K. The 20 MOA base will allow you to go further than 1K and still have 25 MOA down travel, so I'd run a 20 MOA because you can!

Also, I will not go less than 10 MOA on the bottom end (where you have 25 MOA available). If you add a canted base and calculate you have less than 10 MOA on the bottom end, the rifle action, scope base, and rings set up can easily be off by 10 MOA and you risk not being able to zero at 100 yards. I have seen this happen. So if it calculates to less than 10 moa on the bottom end, I won't run a canted base.

Thanks for taking the time to write all that!

yes you will have plenty, and yes zero at 100

I'm running the 5-25 model on my 6.5 CM. With a 20 MOA base, I still have 17 mils of elevation left after my 100 yd zero. It takes me 5.9 mils of elevation to reach 800 yds, so just over half a revolution. That cartridge will be out of steam long before I run out of scope adjustment.

Also, I'm sure you already know this, but that scope comes set from the factory for a 20 MOA base. If your rifle already has a 20 MOA base you should be pretty close, but it's important to remember if you end up slapping it on something with no offset.

Yes, I'm aware of it coming ready for a 20moa base. Thanks!

Received scope today. It looks even better now than t did when I researched them 6+ months ago. Cheese-n-rice this thing is sweeeeeet!!!!! Looked @ a house about 1/2 a mile away through the woods. I could see everything in detail that's on their porch. I could see good enough to easily hit a 10" target (though I lack the skills and gun, just saying the scope is capable).

SWFA has the 4-20 and 5-25 on their sample list, if anybody is looking for one. Please buy them before I cave in!