So I just put a new Remington 700 LR in .300 Winchester Magnum on layaway at one of my fun stores I frequent.  For optics, I will be going with my old standby, a Leupold Mk4 with the M1 turrets.  However, when it comes to the base, I'm not sure if I want to stick with a 20 MOA base like I use on my .308 Remington 700 or should I consider going with a 30 MOA base for added range?  My KD range is marked out to 1,000 meters but I can extend it out to a full 2,000 meters should I feel the need which is why I am considering the 30 MOA base.  However, will I be able to still bring my adjustments low enough to get on target at shorter ranges like 100 meters?

Kinda a wobbler with how far you're trying to get which is just outside the supersonic flight area of a 220gn 300WM load. What I would suggest so that you minimize the amount of times you have to buy the same part, get the 20MOA base and pick up a set of Burris Signature Series Zee rings (assuming your scope is a 30mm tube model). They come with eccentric inserts that you can use to dial in -20MOA,-10MOA, 0MOA, +10MOA,+20MOA. That way if you find you need the extra 10MOA or 20MOA even, you can dial it in by flipping the eccentrics in the appropriate manner. I use them exclusively. They also completely prevent scope finishes from being marred by rings.

One thing though. The ER/T line of MKIV's come with an advertised 60MOA of up in them according to my research (I don't use Loopy Mk-anythings). At sea level you'll need 80MOA or better total which puts you all the way at the dial limit of a loopy no matter how you slice it. I don't know how tied you are to the loopy scope but you might consider a brand or model with more up in the turret. 80MOA at least, 100 would be better. You don't want to use the extremes of a scopes adjustment limit. Makes for optical problems.

I have an S&B 5-25 on my .300 WM (34mm Tube). IIRC, S&B stated that 40MOA cant is ideal to achieve the best use for that optic. I went with 30 MOA.



Not sure how much elevation you have in your tube, but mine is zero'd at 100 yards. Unlike you, I cannot aim-in on a target above my center crosshair (H-59 reticle)




 

I have a 40moa base on my 700, with my 30mm Mark4 I had about 1mil to spare at my 100yard zero.

Without knowing exactly how much UP your Mk 4 scope has, I can't say for sure, but I'd be surprised if 20 MOA is INsufficient to get you out to 1000m with any bullet worth a damn.

Chris

I think he is looking to take it transonic.

Thanks.  I glossed over that tidbit about 2000m, lol.

My Sako 338LM's 3 ring mount is 30 MOA and with my SB 5-25, Sako claims 2000m is doable.

Chris