70 MOA adjustment enough?

[cgbills]

I am building a 6.5 Creedmoor rifle and I am trying to decide on a scope. I plan to use this setup to the limit of the 6.5 CM, but 80% of the usage will be 1000yrds and under. When I calculate a hypothetical load up of a 140gr A-max bullet going 2850 fps at just above sea level, I get the bullet entering into the transonic (1200 fps) at about 1400yards. For all practical purposes, I am saying 1400yrds is about the limit of my setup. Also I am getting I will need about 52MOA of adjustment to get there. So with a 20 MOA base, will 70 MOA of internal adjustment be enough to reach 1400yrds? By my calculations that setup should give me about 55 MOA adjustment up. What if I did a 30 MOA base, would it give me about 65 MOA up? I think it would be very close and would likely be using the reticle to hold over.

I am trying to balance my desire for higher magnification and larger objective with available adjustment

 

[ahage2]

I am building a 6.5 Creedmoor rifle and I am trying to decide on a scope. I plan to use this setup to the limit of the 6.5 CM, but 80% of the usage will be 1000yrds and under. When I calculate a hypothetical load up of a 140gr A-max bullet going 2850 fps at just above sea level, I get the bullet entering into the transonic (1200 fps) at about 1400yards. For all practical purposes, I am saying 1400yrds is about the limit of my setup. Also I am getting I will need about 52MOA of adjustment to get there. So with a 20 MOA base, will 70 MOA of internal adjustment be enough to reach 1400yrds? By my calculations that setup should give me about 55 MOA adjustment up. What if I did a 30 MOA base, would it give me about 65 MOA up? I think it would be very close and would likely be using the reticle to hold over.

I am trying to balance my desire for higher magnification and larger objective with available adjustment

I'm probably not the best person to answer this, so take it with a grain of salt and listen to the pros when they start to chime in over me...but if you are saying that you have a scope with 70 MOA of total internal travel, that would mean (in a perfect world) the scope would have 35 MOA of up and 35 MOA of down. if you put that scope on a 20 MOA base, the scope would then have 55 MOA of up and 15 MOA down....which also means that a 30MOA base would give you 65 up and 5 down. So your math is correct.

I also just threw in a very rough test case of a 6.5 into my ballistic calculator and it spit out about 51.6 minutes at 1400 yards....so technically, assuming the reticle is exactly centered in the scope, and the scope does have that much travel, you should be able to center the reticle on the target at 1400 yards with a 20 or 30 minute base.

Adam

 

[bschneiderheinze]

That would be in a perfect world. I just put a nightforce on my 700 and it ended up being around 15 moa down to get it sighted in. I would count on it being perfectly centered and being able to use the full range. I would give at least 10 moa of wiggle room.

 

[WaltHer]

^^^^+1 for +30MOA

 

[kd185]

^^^^+1 for +30MOA

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