Sighting in MTAC 1-4

[legion85]

I currently have a Stag 3G and will be putting a Burris Mtac 1-4 on it.

I only have quick access to a 25 yard max range (100 yard range is over an hour away) and was wondering how I should sight it in if i wanted to use the reticle as intended with 100 yard zero for the center.

Also I have heard that with the 100 yard zero, people are using the 400 yard dot for 25 yards and under, anyone have any experience and care to help a new guy out?

Thanks in advance.

[bagdrag]

Got access to a chronograph. It could help if you don't have access to longer ranges.

[ziebart]

When I used the Tac-30 I used a 300 yard zero and the 500 or outer ring was spot on at 5 yards. Rarely did I have to be that precise, but it was handy the couple times there were no shoots in your face. The bottom point of the upper "T" was good at 100.

[MarkCO]

With a 3000 fps MV and 2.7" sight-line over bore, you need to be 1.6" below the POA of the center dot at 25 yards to be pretty close to zero at 100 yards.

[legion85]

With a 3000 fps MV and 2.7" sight-line over bore, you need to be 1.6" below the POA of the center dot at 25 yards to be pretty close to zero at 100 yards.

Thanks for the information. Just what I was looking for.

[Flatland Shooter]

For a little more detail I went to JBM Ballistics Calculator (http://www.jbmballistics.com) and ran their simplified ballistics program.

I then matched the MOA drop from the printout to the subtensions for the MTAC.

If my calculations are correct, the MTAC, the subtensions work out as follows.

Center of dot 100 yards -->> ZERO

Bottom of dot 200 yards -1.1 MOA -> ~58 yards

2nd Dot 300 yard -3.3 MOA -> ~35 yards

3rd Dot 400 yard -6.1 MOA -> ~25 yards

4th Dot 500 yards -9.6 MOA -> ~20 yards

5th Dot 600 yards -13.6 MOA -> ~15 yards

For details, look at the printout.

Bill

JBM - Calculations - Trajectory (Simplified).pdf

[alma]

I had the same challenge since the closest ranges to meet only goes out to 20.

I used the Strelok app with great success and highly recommend it.

I needed to measure the scope sighting overall bore, getting ammo velocity, and ballistic coefficient for the bullet.

I don't have a chronograph so I took the rated velocity for my amount and subtracted 100 FPS since I am running an 18 inch barrel and I am guessing test velocities would be 20 inch.

I wanted a 200 yard zero. The calculator gave me 16 clicks (1/2 MOA per click) at 20 yards so I zeroed my scope at 20 yards and then set the target turret to 16 clicks so that zero would theoretically be on at 200 yards .

I was able to stop by another indoor range and shoot at 50 to confirm that I was correct with my work on the shorter range. I think I made some minor adjustments but it was very close at 50 plus 2 clicks (as calculated).

I shot a match with targets out to 300 and the gun was dead on. Having the confidence of the portable ballistic calculator in my range bag was great too because there is no more guess work about drop, clicks and etc.

[bigblock455]

I use an MTAC and I've tried zeroing at 25yds and then check it at 100 yds and I never got it close. I've done 100 yds and check it at 25 yds and it's been better. That's with taking the ballistic calc. into the equation. I say drive an hour and zero at the longer range. It beats getting to a match and not be able to hit the far targets?!

[alma]

I have to think that when using a shorter range to sight in for a longer zero that having the correct measurement of the line of sight over bore is critical given the extreme angles that would be involved. Not sure how others do it but since I have a round hand guard I used some digital calipers to measure I took the distance from the bottom of the hand guard to the top of the scope and subtracted one half of the diameter of the hand guard, and one half of the diameter of the scope above that point on the hand guard to figure my exact line of sight measurement.

[Flatland Shooter]

I use an MTAC and I've tried zeroing at 25yds and then check it at 100 yds and I never got it close. I've done 100 yds and check it at 25 yds and it's been better. That's with taking the ballistic calc. into the equation. I say drive an hour and zero at the longer range. It beats getting to a match and not be able to hit the far targets?!

Agreed. Its always better to zero at the max distance you anticipate shooting but to zero at shorter distances should at least get you on the paper.

For those that do not have access to ranges with longer distances. we just do the best we can knowing that its just a scientific guess further out.

Bill

[Neomet]

The problem with using Strelok to extrapolate 20 or 25 yard zeros out to 200 is that it presumes you are dead nuts accurate at 20 or 25. A 1/4" off at 25Y is 2" at 200 yards. Don't get me wrong, I love Strelok to calculate bullet drop but the issue you are facing at 25 yards is that it is simply too coarse of a measurement to be reliably accurate at 200 and beyond. Way better than nothing but I literally just got back from the range and the adjustments I made when moving from 50 to 200 to fine tune the zero were not as small as one would think.

[alma]

Right, I am definitely talking about the better than nothing approach.

I guess my point is don't just zero at 50 or zero at 25. Zero at 50 +2 clicks and confirm at 25 +12. When you get the chance then confirm at 200. It isn't prefect but I can't rolling onto and public range with 100 yards + without a 2 hour drive in etch direction some I have to make due. Sorry far in have been surprised by how close I have been able to get by just using accurate calculations.

Edited March 26, 2014 by alma

[legion85]

Alright you guys convinced me. When I get the chance, I'm going to make the drive to the 100 yard range. I'll just use the time there to figure out my slugs POI too.

Thanks for all the advice.