One of the first co-workers I met at Fieldcraft Survival in August 2020 in Prescott, AZ was Kevin Owens. A veteran of two country’s armies, former Green Beret, an incredible leader and friend Owens is the company’s resident long-range SME but he’ll downplay his capability. I attribute the ultimate decision I made to join Fieldcraft to my Irish colleague. Kevin is a straight talker and doesn’t beat around the bush. I trust his judgment without question and when he offers advice, I take it. Kevin spent many years behind a sniper rifle, training other snipers, and received the Carlos Hathcock award in 2021. He routinely offers ballistic courses for Fieldcraft Training here in North Carolina and selfishly, I’ve sat in on his course more than once. When I received some upgraded parts for my dedicated scoped AR, I asked Kevin to run me through his process and explanation of “why” and “how” he mounts an optic. Long before you can practice to consistently ring steel at 600 yds with 77 grain 5.56 ammo, you need to mount your optic properly. Here are the basics shared with me and now in this week’s blog, passed onto you.
The scoped AR mentioned in this blog is a 16” Bravo Company KD4 Upper with Surefire 3 Prong SOCOM Flash Hider/Mount, 6V Surefire Scout Light, BCM Gunfighter Charging Handle and Harris Bipod. The lower is a “pre ‘94” Eagle Arms relic from my days in Connecticut that has a Magpul CTR stock with a Larue RISR, Magpul MOE K2 Grip, and Geissele SSA trigger. The mount was supplied by Geissele and it is part number 05-405B. It is cantilevered to help provide the appropriate forward mounting of the optic that gives the optimal eye relief. The optic is a Vortex Razor 1-10x Low Power Variable Optic Part Number RZR-11002. Calling this optic “low power” is almost unfair with the 10x power range of magnification it offers. I’ve used Vortex Optics for many years and have never been disappointed in their performance. This optic with a true 1-10x gives me 2x magnification per 100 yards out to 500 which is toward the upper threshold and capability of the rifle with 75-77 grain ammo it was designed for.
ToolsTorque Wrench (Fix It Sticks)
T15 Star Hex Key
½” Socket Head
White Paper or Light Background
Caldwell Lead Sled or Rifle Work Bench (optional)
We ensured the rifle was clear before placing it in the lead sled as a stable base. I sat behind the rifle and Kevin O. placed the Geissele mount on the receiver rail. It is important not to bridge the gap between the receiver and the forend with the mount as it puts stress on the mount as the forend flexes. The cantilever mount is hand tightened temporarily until the proper eye-relief is achieved. The scope ring caps are removed and the Vortex 1-10 is mounted. With a simple back and forth question and answer with “better” or “worse”, the optic is moved forward and backward until there is no scope shadow in the picture. This process is done with the optic on full 10x magnification. The typical eye relief for this type of optic is between 3” and 3.5” and Owens showed an interesting trick he learned from an optical engineer. A light is placed on the front of the objective lens with a white paper placed behind the ocular lens. As the paper is moved forward and backward from the ocular lens, the spotlight from the flashlight will become finer and finer until it is the most concentrated it can become. According to the ocular engineer by way of Owens, this is the ideal focal length for the optic.
Once the proper eye relief was established, I lined up the vertical line of the crosshair with the straight door frame in the far room. This “plumb bob” of sorts is a relatively easy way to make sure your crosshairs are not canted and an actual high visibility cord can be suspended downrange and used instead. Owens shared this can be done just about anywhere except parts of the middle east where construction standards are not what they are elsewhere and doors may not be built straight. According to Kevin O, the only level that matters is that of the optic. Keep in mind, the barrel is round and it doesn’t know which way up is. It doesn’t matter if your rifle is shouldered in a canted manner as long as the optic is angled properly and the shooter sees the vertical part of the reticle truly up and down. There is no need to level the rifle, level the mount, and level the optic. Just make sure the shooter sees the optic the way it was designed to be held.
When the eye relief was established and the reticle was leveled, the proper amount of torque was applied to the ring screws and clamping nuts. We used Fix-It sticks that have the torque value etched in the side of the wrench head. 15-18 inch pounds were applied to each of the ring screws and 72 inch pounds were used on the clamping nuts. Make sure you know the difference between inch pounds and foot pounds before you damage your kit. It should be noted that as I tightened the clamping nuts, Kevin O. pulled forward on the optic eliminating any gap between the lugs and the picatinny rail. No Lock-Tite was used on any of the screws per Geissele’s recommendation. Additionally, we did not exceed the torque value as this can damage the rifle or optic.
After the large motions of mounting the optic and cranking it down came the small adjustments. The fine focus adjustment at the ocular lens head was rotated until the reticle was as crisp as possible. We checked the battery in the LPVO that illuminates the reticle and stored the additional provided batteries in the grip of the rifle. An Accuracy 1st bubble level was added to the optic and the miscellaneous paperwork and spare parts were set aside. Kevin O. shared plenty of pearls of wisdom along the way and proved his level of competence multiple times over with anecdotal knowledge and very specific facts I neglected to write down. I’ll just sit in on his next ballistic class and hope he reiterates them there.
With a properly mounted LPVO optic, the next step is achieving a proper zero to your preference. Traditionally, rifles are boresighted or the bolt or bolt carrier group is removed to look through the barrel at a target and the optic is adjusted to the center of that target. This is done with the rifle in a stationary rest. Another method is to get on paper at a shorter distance like 25 yards and then pushing back to 50, 100, 200 etc. Once your rifle is zeroed, you can chronograph the ammunition used and input the data from your rifle and ammunition (twist rate, height over bore, zero distance, ballistic coefficient, bullet weight, etc) and test your rifle at varying distances with the tables the Kestrel provides. If you don’t have the luxury of having a chronograph like a Magnetospeed or Lab Radar, you can get walk-back analog data by shooting a 5 round group at the same aiming point moving back to in intervals of 25 yards, 50 yards, etc and identifying the center of each of your groups marking the drop from the zero. This method is more costly with the current price of ammunition. Once you have your LPVO dialed in, you should zero your offset irons or offset red dot. The advantages a magnified optic like the Vortex Razor series provide over a standard dot are unquestionable. All that is left is to get quality training from guys like my friend Kevin Owens or the other firearms trainers. Your training will continue to evolve as you learn how to push your rifle out to further distances with quality ammunition, solid fundamentals, and a properly equipped rifle that has had optics mounted as described here.