when would I ever use 70 MOA of cant ?

[longshot2000]

My "long range" rifles have 20 to 30 MOA of built-in cant on the top rail, and I am looking at some deals on scope mounts with 40 MOA of cant. In these rifles, I am shooting one of three rounds:

> .300 WM
> 6.5mm Creedmore
> .308/7.62 NATO

for the .300WM, I could be shooting 1,000 to 1,400 yards, and much further in for the other two. My scopes are 34mm tube high-end scopes from Vortex, NF and S&B.

I guess my question is: will I ever need 40 MOA built-in cant in a scope mount? Sounds like a lot to me. I know the .300WM starts to drop fast after 1,000 yrds, but with 190gr to 220gr bullets, I am generally looking at 250" at 1,000 yards, which sounds like 25 MOA, and maybe up to 700" at 1,500 yards, so now we starting talking about big needs, but sounds like less than 50 MOA.

Open to thoughts from long-range shooters.

 

[roggom]

Well if you really need to have 200+ moa of travel, but it seems excessive. Im hitting 1000 with a 260 with a 0 moa rail with a simple Luppy VX3i LRP.

 

[VegasHKShooter]

I have an A.I. in 6.5CM. I'm hitting at 1250 with 11.12. I have a 20 M.O.A. Rail, and mount, so 40 M.O.A. total. That's still on my first revolution (I shoot mils). I can't imagine a need for 30 more M.O.A. unless I'm seriously missing something. The 6.5 isn't a great 1 mile round, so maybe if a guy was constantly shooting ELR then maybe. If that were the case though, you'd choose a different caliber/cartridge.

 

[lash]

For the shooting that you are talking about 20 MOA rail only is more than enough.

 

[BurnOut]

To shoot a 45-70 at a mile?

 

[Fursniper]

I'd put a 30 on the WM because sooner or later you'll end up pushing it to its extreme capability of range and a 20 on everything else.

 

[sgtsmmiii]

I used a 40 MOA Farrell base on my .300 WM with a Sightron 8-32X 56 scope with 70 MOA internal that I shot at 1820 yards. I was out of adjustment in the scope at that range. I was shooting the 175 Sierra TMK's. So, if you get a chance to really stretch your gun out, it might be nice to have that much adjustment ability.

 

[hamstur]

if you go extra +40MOA over the base, make sure you have the extra +11 mil of erector adjustment to be able to set & achieve zero

 

[Downtown]

https://www.snipershide.com/shootin...s/6603011-scope-for-my-7-62x39-16-ar-15-rifle

 

[WaltHer]

You could use your ballistic computer to determine your rough max possible range with this mount by taking 1/2 your scopes total available come-up and adding the cant of various mounts and comparing that to your predicted drop at distance. Conversely you could take your predicted drop at the distances you intend to shoot, subtract 1/2 your scopes total travel and then decide how much cant you actually need, if any, to achieve those distances. This assumes that your zero is achieved at approximately the middle of your scope' s total travel.
I use the DT +40 WITH an NXS on a DT .338 giving me a total of +96MOA for a max range of about 2100 yards in avg. conditions before having to begin holding. The Spuhr +44.4/ATACR combo on my HTI gives me a 102 MOA with a max range of about 2475yds. I dont regularly max the turrets out but I have, and routinely shoot to distances requiring more than +20MOA.
That being said, most "experts" say that scopes perform best optically when they are close to center. I'm not sure that I have ever noticed. In the end there is little reason NOT to have all the come-up available provided that, as hamster noted, you have enough total come up in your scope to offset the cant so that you can achieve a 100 or 200 us zero-if that is your desire.
In the end don't buy a mount with more than 1/2 the total travel in your scope, preferably a little less. For example if a NF ATACR has 120MOA total travel, don't buy a mount with more than 60 MOA (including tapered rail if you have one), and preferably a little less, e.g. Spuhr +44.4.

 

[FatBoy]

I run a 40moa Nightforce base on my 300wm w/5.5-22 NXS . This not only allows me to dial out to a mile with 230OTMs (which I don't have access to yet) with about 10MOA left, it allows me to zero at 100y (about 18moa off the bottom of the erector). No zerostop required. It made the most sense to me, and I have had zero issues with this setup. Needed? Maybe not but it certainly has advantages for me.

 

[longshot2000]

thanks for the notes. Confirms what I thought. The times I would use 70 MOA of cant would be very limited.