I am a shooter and hunter interested in being able to extend my effective range at which I can confidently take a shot when hunting big game. In the process of looking for a scope with a ballistic drop compensation (BDC) reticle for a new rifle, I realized that the variable power scopes I have on my existing rifles are, in fact, precision measuring instrument. By using the tip of the lower thick post and adjusting magnification, I was able to fine tune my scopes with duplex reticles to provide accurate shot placement at ranges out to 400+ yards. The detailed steps to accomplish longer range shooting with a duplex reticle are covered in the article below (click link).

Bullet Drop Compensation with Duplex Reticles

The primary purpose of this post is so I could attach a zip’d Excel file referenced in the article that allows a hunter to create a ballistics card for their rifle that gives the reference data for accurately shooting big game at longer ranges (see attachment below). The article also includes a simple strategy to use the crosshairs and tip of the lower duplex post for two specific “zero” ranges, e.g., for my .308 with 125gr Nosler BT and Leupold VX-II 3-9x, I zero’d the crosshairs for 200 yards and the tip of the post for 18-inches of trajectory drop at 400 yards by using 8x magnification. This power setting also gives a range estimate to a deer-sized game so I know I am not taking a shot beyond my chosen maximum distance.



The second purpose of this topic is for Members to post their comment on the article and the technique of using the tip of the lower duplex post for longer range shot placement. If you have doubts a shooter can accurately use a duplex reticle for longer range shots, I have had other shooters use this technique. In one situation, a fellow hunter had asked me out to shoot on his land. He had set-up 16-inch white pizza boxes 410 yards away on a calm day. He was shooting a .270 Win with 130gr factory ammo and trying to estimate the hold over he needed to hit the box. After the first round of misses, I suggested he use the range estimating feature of his Leupold VX-III, which is based on 18 inches. He set the scope’s power to achieve 18 inches at 400 yards on the magnification ring and then used the tip of the lower duplex post to aim with. His shots were then on target.

If you become interested in scopes with BDC reticles, review
Scope with BDC Reticles for Centerfire Rifles

If you want to post comments about a BDC scope, please switch to this topic.
Topic about Scopes with BDC Reticles

The article explains a method for deriving bullet velocity by sighting in your rifle at 100 yards and measuring bullet drop at a longer distance of 250 yards or more. I got to run my loads through a new chronograph today and expand my understanding of what is happening with my bullet velocities and trajectories. The Digital ProChrono from Competition Electronics worked beautifully with no confusion about what buttons to push to find the data I wanted. I shoot 100+ round through it with not an error.

Here were the average velocity for my loads.
_______________ Chrono __ Derived from bullet drop
Barnes 110 TTSX _ 3313 fps _ 3375 fps
Barnes 130 TSX __ 2994 fps _ 3150 fps
Hornady 130 GMX 2999 fps _ 2875 fps
Berger 150 VLD __ 2650 fps _ 2800 fps

As you can see my derived bullet velocities by sighting your rifle in at 100 yards and using bullet drop at 250 and 300 yares come in a poor second to having an accurate chronograph. It looks like I could get within 150 fps which gets you in the ball park. You just can't rely on the trajectories you calculate from this. There is no substitute for practice and shooting at these longer ranges.

Now take your actual velocities and run them through Point Blank to see if they coincide with the drop you got when estimating your velocity !!!

Here is another good example of how a duplex reticle can be used for BDC at longer ranges. My hunting buddy asked me to set-up a load for him that he could feel confident shooting deer out to 300 yards. I choose the Barnes 110gr TTSX because of its flat trajectory. With 59.4 grains of H414 we were achieving 3300 fps. With a 250-yard zero, he would be 3” low at 300 yards and never higher than 2” inside of 250. He likes to hunt on 10x with his scope. This gives him a nice set-up because a deer, assuming an 18-inch chest depth, would fill the crosshairs from the tip of the lower post to the tip of the upper post at 300 yards. This means if the deer was larger in the chest then the thin duplex crosshairs, it would be inside of 300 yards and he would only need to aim with the crosshairs and shoot. I also told him if he could learn to shot with the lower post, he could be accurate out to 400 yards on 10x.

So, I took him out to the TacPro's 300, 400, and 500 yard ranges for some practice. It was a beautiful day. Sunny, upper 80s to lower 90s, and light winds. The winds stayed below 5 mph but came in every direction and constantly switching and varying velocity.

The rifle was not sighted in for 250 yards yet and with only a 300 or greater shooting range available to use for the day we adjusted the crosshairs to shoot 3 inches low at 300 yards and 1 inch low at 400 yards shooting using the tip of the lower post to aim with. The reticle's lower post gave a 12-inch hold over at 400 yards with his Leupold 3.5-10X scope on 10X. Below are the results. He was shooting under 1 MOA all morning which pleased me to no end. The one long vertical line is the first two shots after adding clicks up in elevation. Looks like it took a couple of shots for the scope to "settle" into its new setting. The 3 shots after that are the small two-hole group on the right.

He wanted to try 500 yards so he adjusted his scope to 5x and sent two rounds down-range. They were well grouped but high. We still need to practice more adjusting magnification to shoot beyond 400 yards. I think he will be better off not adjusting and practice using 10x with hold over since the crosshairs to lower post is 12 inches and would be quicker to use than adjusting magnification. We will have to practice both

The last 3 shots, as he was running out of bullets, were 2 @ 300 yards and 1 @ 400 yards (next to the pink sticky that covered a shot he called that he pulled). These were real confidence builders for him because they were exactly where they needed to be. You can see the affects of the shifting wind by some that have significant horizontal spread and the changing POI.

We will go back a couple of times more before hunting season starts so he is well practiced and can learn to you the left and right tips of the duplex reticle for windage.

Here is the data card we prepared.

The bottom post of my fixed 4x is spot on at 100m for my 22

Good work Slim. Whichever way you look at it mate...that target shows me "Minute of Deer" with every shot.

Cheers, Vince

Thanks, Vince! It's nice to have that "minute" of deer at 300 and 400 yards. Especially, with the improvement shown in that rifle that couldn't shoot that well at half the distance before we bedded it and worked up a handload.

man...I just think Ive got things worked out and along comes Slim and gets me thinking AGAIN......good job slim.

Thanks, Elvis. This really works well. I set my buddy's .270 up like this and he was busting rocks at 630 yards. There is a point of diminishing returns because your magnification has to get less to shoot at longer ranges. But it does work while he is saving up money for his long-range mil-dot scope.