22 Sep

>Actual Maximum Parallax Error in Inches Regarding Leupold Riflescopes Viewed from 50 to 400 Yards

Steven K. Ledin,


I’ll be leaving next Monday for an antelope hunt in Wyoming. I needed a new scope. Those of you who read this blog and my forum posts are aware that I don’t like bells and whistles and unneccessary functions that just get in your way and tend to take your head out of the game. An adjustable objective often does this because you’re always wanting to fool around with it and get the clearest picture possible. An AO is not always necessary anyway on big game with riflescope magnifications of 10, 12, or 14. Since I’ll be shooting a custom Ruger 77 rechambered to the super-flat shooting .270 Weatherby with 130 grain Nosler Partitions, I wanted to use a new Leupold VX-3 4.5-14×40 without an AO or side focus, but I didn’t know how much parallax error was possible at different distances. I’ve never seen an answer to this question, so I decided to test it.
I took a Burris sight-in target with one inch grids and taped it to the rear window of my Jeep. A coworker, Trevor, took one of my Motorola radios and drove the car 50 yards according to my excellent Leupold RX-1000 TBR compact laser rangefinder, then stopped when I told him to. I had three different favorite Leupold scopes with me. My trusty VX-3 3.5-10×40, my VX-3 4.5-14×50, and my Mark IV 8.5-25×50 LR/T. I wanted to find out the parallax error difference between the maximum of 10x and 14x, and wanted to see how well the adjustable objective on the Mark IV removed parallax. All three scopes were tested on a sturdy Nikon #748 carbon fiber tripod on a concrete foundation with no vibration.

At 50 yards, scope #1 (the 3.5-10) had a maximum of 1″ error at minimum and maximum power, tested by moving my eye from side to side and up and down until I lost the picture. The one inch grids on the target helped to easily determine error. Scope #2 (the 4.5-14) had one inch of error at low power, and 2″ at 14x. Scope #3 (the 8.5-25) was right on at all magnifications.

At 100 yards, scope #1 and 2 had a maximum error of one inch at high power. Scope #3 was right on.
At 150 yards, which is the factory parallax-free setting from the factory, scope #1 had an inch of error at 10x, and scope #2 had an inch and a half at 14x. Surprising. No error at low power.
At 200 yards, scopes #1 and 2 had a 2.5″ error at high power and low power.
At 250 yards, scope #1 had a 3″ error at high power, and scope #2 had a 4″ error at high power.
At 300 yards, same error.
At 350 yards, scope #1 had a 4″ error at low and high, and scope #2 had almost 7″ of error at 14x.
At 400 yards, scopes #1 and 2 had errors of about 8″ at high powers.
Scope #3 with the AO was correct at all distances.
The caveat is that nobody, no matter what kind of contortionist hold they have on the gun, will have their eye so far from ocular center while shooting, therefore making the test simply acedemic, rather that practical.
So, I decided to get the 4.5-14 without an AO, and the minimal difference the parallax error makes at distances as far as I will shoot big game, will not matter.
I didn’t check any further than 400 yards.

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