Bought a new basic tactical scope today

I wanted a utility scope that could be dialled quickly and accurately ,was calibrated in Milradians and had a ballistic reticule as well as practical dialling. The intended range was out to 700 metres.

I looked at several brands and specs, but must admit I have been a long time user of Léopold's and trust their backup implicitly, along with the fact that they have been providing the US military for a long time now.

I wanted a scope that was lighter than the large 3-12+ tactical ffp scopes which are heavy, and was reasonably priced.

My (personal choices) selection came down to either a Vortex Viper 3-9 by 40 at around $500, but only available in MOA turrets and holdover reticule, or Leupold Mod 1 AR 3-9 by 40 which had a milrad ballistic reticule and milrad turrets with the elevation turret incorporating a dialup scale suited to military .224 ballistics, but the distance scale on the elevation turret was in yards, not metres:(
I much prefer to use mls with metres (not yards) as no fancy calculations and conversions are required.

My rifle is .308 and the rounds intended are 135 grain SMK's with MV 2930 fps. My problem if I went with the Leupold was how to best use the elevation turret for quick dialup using .308 instead of .224. On researching and reading Leupold information booklets I found they made a comment to the effect that if your rifle was slightly different ballistically from the standard military 223 round, that using a zero of around 300 yards would result in only small variances in compliance with the turret elevation range readings. I decided I might be able to work my way through that issue as well as the yards vs metres problem and asked Taupo Fly and Gun to order me a scope. Price was under $600.

After a few hours experimenting with on-line ballistics calculations I discovered that if I zeroed my rifle as 180 metres, that out from point blank to 215 metres the variance from the distance scale (reading it as if it were metres instead of yards), was less than 5cm plus or minus and beyond that, the dial read pretty much exactly true in mls corrections for the range indicated (but read as metres not yards) right out to 700 metres; so I am a very happy boy :)

Admittedly not ffp but 9 power on 2fp for using the ballistic reticule is tolerable and with the combined ml / distance calibrated top dial being confirmed so accurate by using a 180 m zero, the magnification setting doesn't matter a jot and very quick sighting is possible using the crosshair alone after rapid dialling to the range selected! The weight is only 14 oz. Awsome.

Excellent, well researched and always good to see somebody happy with their choice.
Have you confirmed your on line ballistics ?

Pics?

Quote:

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Originally Posted by jakewire

Have you confirmed your on line ballistics ?

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Yep, be annoying to go through all the research and then find out your rifle doesn't quite shoot they way it theoretically should...

Will be testing starting today and then over some weeks before the Hihitahi.
According to JBM, my chrony, and the gradations on the turret I should be pretty close. Will let you know. :)

I know the load is good and groups .3 moa.

Tested at 180 and 400 metres today. POI was spot on for both. Dial reads .2ml on the lower scale of the dial at 180m on the top scale of the dial for zero, but from that point on, the POI's and dial readings seem to coincide very closely or exactly. The maximum error would be 5cm high at 75 metres and 3 or 4 cm high at 40 -150m
Therefore the theory I calculated works fine in practice.

For different bullets, Mv's, bc's etc the zero range would have to change from the 180 m zero I use but in essence, for most hv cartridge loads this system would work fine at medium ranges at least out to 700 metres, perhaps more.

In principle, if you plot / graph the trajectories of various loads one over the other, with the key trajectory being the US military .223 which the dial is calibrated for with a zero of 100yard, and then move the other trajectory lines until best fit is achieved over the key one, you should be able to determine a compromise zero range instead of using the 100 yard zero used when Leupold printed the dial. The resultant errors will be small but will be greater on slow poor trajectories than faster flatter ones.

Of course, at longer ranges, the 223 will start dropping away quicker than some loads so errors might creep in at extended very long ranges. With my load this is not an issue, but it could be for some.

For more detail and clear pics of the P5 dial, look up AR mod 1 Leupold and P5 dial; -also their ballistics handbook to better understand the theory.

For, I now need more practice alongside a friend with much sharper visual acuity than I to spot POI's on the discs for each shot.

Incidentally, the specs for this scope seem to be more or less equivalent to the Leupold VX1, but my impression of the sharpness and clarity my scope is exhibiting indicate to me something superior to many other more expensive scopes I have looked through recently. I have been amazed frankly.