Any one running this?

[dingos]

Ok, defiance deviant action for 338 LM in an AI AT chasis with a vortex HD Gen II 4.5-27x56 scope. What rings and height are you using? I'm trying to determine ring height before its assembled. I know the correct answer is wait and test with different heights. Was hoping someone here has this combo or close to it for an answer. I want to buy nightforce rings so when I get the rifle back assembled I can plug n play.
Thanks.

[blsniper]

It's also going to depend on the barrel contour that you're going to have. And yes, wait till its all together if you want to be safe. If I was going to guess of the top of my head Id say medium height would be fine.

[JMP]

Are you asking about scope cant or height?

For a 338LM, I'd suggest getting a high mount. As long as the mount doesn't move in relation to the rifle, contrary to popular belief, you are not hurt by mounting it high. Bore height and the concept of having your bell as far down as possible is mostly important when you are shooting close up. Namely, it makes it much cleaner for shooting before your zero and potentially for a brief period after your zero. The other issue you could have is that a high scope may not give you sufficient cheek weld, but that will not be an issue with an AI stock as they have plenty of adjustment in the cheek.

However, with a 338LM, I'd presume that you are shooting mostly further. If that's the case, I actually prefer to mount the scope rather high as this helps to avoid issues you may have with mirage from the barrel when it heats up. Also, when you rebarrel or get an additional barrel, you do not want to worry about the fit again. I started with a Finnish 338 Lapua barrel, which has a rather light contour relative to other operators. Thus, I had no concern when I needed to rebarrel. I got another Finnish style contour for 338 Lapua Magnum and a beefier contour for 338 Lapua Magnum Ackley Improved. Having a high scope, there is no concern about the potential contour of your next barrel.

What you definitely want, if you are planning to shoot far, is a steep enough cant. As a rule of thumb, I've generally found that 45 MOA is about right for most 34mm tubes.

[Dead*Reckoned]

JMP, with a 45 moa cant what distance are you using for a zero? Need to get a scope base for my rifle. Not planning on using it ever closer than maybe 800 yards either.

Sorry for hijack OP

[JMP]

JMP, with a 45 moa cant what distance are you using for a zero? Need to get a scope base for my rifle. Not planning on using it ever closer than maybe 800 yards either.

That's for a 100 yard zero. Almost all 34mm scopes will accommodate a 100 yard zero with 45 MOA. The reason I go with 45 MOA on my 34mm scopes and 18 on my 30mm scopes is that's where Accuracy International set its mounts, which I have found to work quite well. I've always used the AI 5656 mount with 34mm scopes. That mount was really designed for the Schmidt & Bender 5-25x56 for appropriate cant and clearances with their contours. However, with the new quad rail style, an AI 5656 will just barely clear a full straight picatinny rail with a Schmidt & Bender. That's why they came out with the new AI 4276, which is a bit higher. I always use these mounts with a flat picatinny as they are about $170, and you can't really beat them by much.

For extended long range, last year I made a switch to the new German 36mms, and those work well at about 70 MOA as that still provides a 100 yard zero. I like reasonably close zeros as it makes it more convenient for load development at your zero then you do not need to fritz with the scope as modern scopes will generally have plenty of elevation. The European scopes generally will only put 26 MRADs into their 34mm scopes as they demand perfect tracking without distortion, so if you use a 45 MOA, this lets you go up 26 mil from 100, which will get you pretty much as far as you need to go. Other scopes will allow the erector assembly to go even further to the extrema, so you may find that you can do more if you need it.

Really, though, once you've hit 20 Mil of elevation, shots become quite difficult to make no matter what you are shooting. Ultimately, it will depend on your scope and the most common distances you will be shooting.

For more flexibility, some mounts are coming with adjustable inclination cants such as Recknagel (ERA-TAC), which makes good quality mounts, but at a higher price. For a long range precision bolt action rifle, you can save some money because you should completely avoid anything that has QD levers as they tend to simply not cut it for holding the mount on tightly enough with a heavy scope. You want a mount to bolt down, not clip down. Of course, I am referring to one piece mounts as opposed to rings as I do not use rings for extended long range as I greatly favor a one-piece mount.