Trying to wrap my head around this long range thing

bukwild

bukwild

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Ok Im trying to figure out out shooting out to 1000yds. Here is what I have.

Remington 700AAC
MDT TAC21
Vortex HST1 MOA
Strelok calculator

My problem is this when entering 180gr .308 with BC of .496 at 2450f/s. My scope hieght I figure about 2.9 inches, 1000yds gives me a calculation of 41.18 MOA. The scope has 65 moa adjustment so being zero'd at 200yd I have less than 32 MOA of vertical adjustment. I have old eyes and if i use any power greater than 13 without adjusting MOA on the scope then the target will not be in the reticle. Can I adjust MOA partially and use a higher power to see better? if so how? Am I way out in left field and missing something? I'm also away from home and not with the actual equipment to figure this so what I'm doing is the just figures.
 
First I'd figure out how much adjustment range you actually have left in your elevation turret. Is the top rail o the Tac 21 canted (ie 20 moa or so)? In which case you may have more elevation to play with than you think. In any case, I'd dial that elevation turret as high as you can go without forcing it and that is your max elevation. From there you can hold over whatever other elevation you need to get on target. ie if you can dial up 30 moa you can hold the other 11.25 moa in the reticle. What magnification you can do this on depends on whether your scope is FFP or SFP. If it's FFP, you can holdover at whatever magnification you want. If it's SFP, the subtensions will only be correct at a set magnification (usually max) although you can figure out what they are by doing a bit of math.
 
First off, your scope isn't 2.9" above the bore. Probably closer to .9" or so. And your zero at 100 yards isn't necessarily in the mid range of your moa adjustments. People put moa bases on their rifles to gain more moa by angling the scope more.
 
Try installing a 20MOA rail to give you the extra elevation adjustment on your scope. If that doesn't work look at getting a scope with more internal adjustment like i am in the midst of doing. The Nightforce ATACR 5x25 has 120MOA internal adjustment!! I have a Ruger precision in 6.5 CM with a 20MOA rail and vortex PST 6x24(65MOA internal elevation). My first day shooting with that setup i was able to put 13/20 rounds on a 14"x14" plate at 1000 yards with Hornady 143grain eld's using a ballistic calculator on my phone and a kestrel wind meter. Took a long time to get the smile off my face. Hope this helps a bit.
 
Sorry guys, to clarify the MDT TAC chassis has 20 MOA built into it and I have High rings. Im going to look into the FFP scopes and do some math here. Thanks.
 
I dont think a FFP scope will help you gain much. If you are able to hit 1000 yards your going to want to keep stretching out further. Look at options to gain more MOA without having to rely on the elevation in your reticle. There is a few companies that make adjustable scope rings or bases. Take a look at the IVEY adjustable scope mounts. I am running into this problem with my RPR with now wanting to stretch out to 1500 yards.
 
savagelh said:
First off, your scope isn't 2.9" above the bore. Probably closer to .9" or so. And your zero at 100 yards isn't necessarily in the mid range of your moa adjustments. People put moa bases on their rifles to gain more moa by angling the scope more.
Click to expand...

This depends on the rings. You measure from the center of the bore to the center of the scope tube. I have scopes that are 2.7" above the bore and some that are 1.5" on my hunting setups.
 
I really don't see the point in throwing a bunch of money at this issue. For one, you don't know how much elevation travel you actually have, figure that out. With the top of the Tac-21 already canted at 20 MOA, odds are you have enough elevation travel anyways. Wait till you get home and have your gear in hand, make sure all your measurements are correct (ie height over bore), punch the numbers into strelok and see if you have enough elevation. Odds are you're fine.
 
Go to a 100m range.
Set up a tall sheet of paper with an aiming mark toward the bottom of the sheet and a straight line running the length of the paper. Use a plumb line, and make sure the centerline is vertical.
Zero the rifle on the aiming mark. Wind up the elevation, firing a shot every five minutes of elevation. See how much actual elevation you actually have. See if the change of impact is consistant with the change in elevation. The shots should stike very close to the vertical line. If they stray off to the side you will know that you don't have things set up true.
40 minutes of elevation will result in your shots climbing over 40 inches at 100m.
You can dteremine if you actually have the elevation available that you acutally need.
If you don't have enough elevation, use some Burris Signature rings with eccentric inserts to get more. Simple solution.
Incidentally, I shoot a .260 with 139gr Lapua Scenars. My elevation change from 100m to 1000m is 31 minutes.
 
Since you have already zeroed your scope and confirmed there is 32MOA of travel on your scope, then the easiest is to shim the scope.

Burris Sig ZEE or XTR Sig rings... Shim your scope by raising the rear and lowering the front. Rezero the scope so you have more travel.. EASY.

Many competition shooters will shim their scope so that the middle of the scope travel covers the distances they typically compete at. This is the most stable mechanically of any scope AND the best optically.

Worry less about what the smartphone says and just go shoot the set up. Do the tall target test as described above. That will tell you more about what is actually going to happen with your scope... and confirm that your scope will track properly

Good luck.

Jerry
 
tiriaq said:
Go to a 100m range.
Set up a tall sheet of paper with an aiming mark toward the bottom of the sheet and a straight line running the length of the paper. Use a plumb line, and make sure the centerline is vertical.
Zero the rifle on the aiming mark. Wind up the elevation, firing a shot every five minutes of elevation. See how much actual elevation you actually have. See if the change of impact is consistant with the change in elevation. The shots should stike very close to the vertical line. If they stray off to the side you will know that you don't have things set up true.
40 minutes of elevation will result in your shots climbing over 40 inches at 100m.
You can dteremine if you actually have the elevation available that you acutally need.
If you don't have enough elevation, use some Burris Signature rings with eccentric inserts to get more. Simple solution.
Incidentally, I shoot a .260 with 139gr Lapua Scenars. My elevation change from 100m to 1000m is 31 minutes.
Click to expand...

Good advice. I shoot a 6x45 and at 1000 I am looking at ~39moa
 
I have Burris rings with canted inserts and a 20MOA rail, shoot lighter bullets at faster speeds and have just enough adjustment in my Bushnell to dial up to 1000m.

32MOA (1/2 adjustment range assuming dead center zero) + 20MOA from the chassis rail = 52MOA so you should be good to go. How's your velocity downrange at 1000 from the short barrel? I would be more concerned about that at this point than dialing the adjustment.
 
In the past I have shot the 308 to 1000Mtrs. I used a 40X, 27" barrel with 155gr at 2900f/s. With this combination I had to be 42" high at 100Mtrs. With 180gr and 2450f/s you will have to be higher.
Using the Burris zee rings with a + and - inserts of 0.020 may get you there. With that scope and the limited amount of adjustment 32 MOA you will not be able to adjust 100 to 1000yds without making a physical adjustment of the scope. IE, reversing one set of the inserts using the burris rings. Been there done that.
 
What I find hilarious here is everybody is offering this guy advice on what to buy, etc when he doesn't actually know how much elevation travel he has in his scope as he is away from home. Everyone is working on the premise that he is centered in the elevation travel of his scope which nobody knows for a fact.

What I can tell you is that the scope on my .308 has 30 mils of elevation travel and zeroed at 100 yards with a 20 moa rail, I have about 21 mils of elevation (which gets me to 1500 yards). If you subtract 20 moa from 1/2 of 30 mils, you get roughly 9 mils which makes sense, considering how much usable elevation travel I have. To apply that to the OP, you could subtract 20 moa from 1/2 his total elevation travel which would give you 12.5 moa. Add 1.5 moa or so to get to 200 yards and he should still have about 51 moa of usable elevation which will be plenty.
 
^^^..lol, not to confuse things..

Just go to the range and shoot, zero your rifle at 100yds.
Count your remaining elevation..that is it..done..
 
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