| cheaptrick wrote:|
SWFA sells them.
Leatherwood 3D Mount Test and Evaluation
The mount arrived in an undamaged, unopened package. Upon opening the package, the Elevation Side Wheel Locking Nut and spring were not attached/screwed onto the MOA Adjustment Dial. The spring was “rough cut”, making it a little difficult to install. I ended up using the blade of a very small screwdriver to hold tension on the spring until I could get enough “bite” on the screw to screw it down. Once two full turns of the screw were made, the adjustment was repaired.
There were no instructions in the box. Having owned a Leatherwood scope for several years, I was somewhat familiar with the mount design (the mount overall is similar to the Sporter ART mount) and was able to determine most of its function. I did finally contact Hi-Lux Optics Customer Service and they emailed me a one-page description of operations. The instruction is lacking in clarity and detail and really should be rewritten and expanded. Much is left to the understanding of the user. I am fortunate to have had some prior background in reverse engineering.
The 3D Mount is designed for a Picatinny rail. In order to install the mount on my BAR, I had to modify a Weaver mount to accept the 3D Mount Locking Lug. It required some tedious filing, but nothing very difficult. Proper care to ensure precise alignment is key.
Once the initial issues were overcome, I placed the 3D Mount on the rifle. The 3D Mount weighs 2.5lb, so it is a significant “chunk of iron” to carry. It is a simple matter to adjust the Mount screws to hold the Mount in place. A word of caution here… the instructions stress that the Mount screws should only be hand tight. I found in firing the rifle, those screws will work loose after a few 30-06 rounds. I had to re-zero at the 500yd rifle range, after my initial zero a few days earlier. I ended up having to use a pliers to get the screws to stay tightened. CAREFUL tightening will not result in damage to the mount, but the size of the screws is not conducive to successful hand tightening, at least with the mount I have. I recommend extreme caution when tightening these screws. I checked the alignment of the rings built into the 3D Mount, found them exactly aligned and placed a Swift Premier 4-12x44 scope in the rings. I adjusted azimuth (windage) using a laser boresighter and the azimuth adjustments on the 3D Mount. The elevation was nearly perfect, no adjustments needed, so I locked down the screws on the mount with a Wheeler Fat Wrench set to 15in/lb. One of the screws would not tighten. The screw hole appears to have been improperly tapped. I could find no sign of the screw being “stripped”. The upper insert (1”) on the rear ring would not fit the mount with the scope in place. Fortunately, with the lower insert in place, there was sufficient adjustment on the upper portion of the ring to allow the scope to be positioned and the ring screws tightened.
After further investigation, it turns out that the ring mount screws are too short with the 1” inserts. I finally managed to get the other 1” insert top half to “seat”, but was then UNABLE to get any of the screws on the rear ring mount to go into the screw holes. This is not insurmountable, but is an issue that requires correction.
Mount Test (Range test)
I arrived at the 500yd range at ~1210 CDT 12 July 2008 with my wife, who served as my spotter. Conditions were: Temperature 92degF, humidity 95% (later thunderstorms with extremely heavy downpour), winds varying from 0-25mph, constantly changing directions. There was no way to truly “dope” the winds, so I just tried to wait for “dead spots”.
(The original zero was at 200 yards, but I performed calculations for 100 and 200 yard trajectories. Before firing at the 500yd range I re-zeroed to 100yd. The reasoning was to enable a more robust test of the Mount MOA adjustment capability and I had to rezero due to the Mount screws coming loose. )
I set up targets at 100, 200, 300, and 500 yards. The range operator confirmed the distances were true and my laser rangefinder agreed.
My first shot, from a rice and sand filled benchrest bag, with the 3D Mount set at 0 (zero) MOA, was at 100yds… dead center bullseye (where I established my zero earlier). Since my purpose was to test the MOA adjustment capability of the mount, I moved to 200yds. I fired two rounds at the 200 yard target and both were dead center, ~2.5inches low (read by my spotter and confirmed by me).
I dialed in 5MOA on the Leatherwood 3D Mount and adjusted down 6 clicks on the Swift scope elevation adjustment. A thunderstorm moved in, but I fired one shot and spotter confirmed a high dead center hit. That would be consistent with my calculations which showed 3.3MOA adjustment required at 300yds. One click on the 3D Mount is 5MOA, I adjusted down 1.5MOA on the Swift scope, leaving me slightly higher than center.
I waited for the storm to pass and moved to 500yds. I dialed to 10MOA on the 3D Mount adjustment and left the Swift scope adjusted 1.5MOA low, since my calculations showed 8.3MOA adjustment required. The second thunderstorm hit, but I fired two shots which registered 2in high and 1in left of bullseye. That, once again, is consistent with calculated impact. The one inch left was possibly due to wind, which was gusting unpredictably as the thunderstorm increased in intensity. The storm finally got so heavy, I could not see the 100yd target, much less the 500yd target.
We packed up and left the range.
Further inspection and analysis reveals that the one inch left error was due to the main mount windage (azimuth) adjustment screw coming loose. It appears all screws on the mount must be seated with loctite to keep them from working loose. I have not experienced this phenomenon with any other scope I have ever mounted. There appears to be an issue with ring screw length, at least on this mount.
I cannot speak to repeatability, as this is the only true test I made of the 3D Mount. However, the Mount did provide performance very near the calculated values. There are some quality issues I would like to see resolved, but overall the mount performed well. Individual shooters will have to consider the weight of the 3D Mount and determine if it would suit their purposes. For long-range competition, I do not think there is a faster way to “dial in” MOA adjustment. Given the 5MOA increments and good ballistics calculations, a shooter should never have to adjust more than 2.5MOA (up or down) with the scope elevation adjustments. 10MOA is 2 “clicks” with the Mount rather than 40 “clicks” with the scope adjustment at .25MOA/click. When I can get to a much longer range, I would very much like to try the 3D Mounts full MOA adjustment capability. 500 yards only scratched the surface.
There is some real utility to this mount. Certainly it will take some “getting used to”, some realignment of thinking. However, it can bring a whole new level of speed and ease to long range shooting. It IS NOT for everyone… yet. With some attention to quality issues and detail, the mount could be a real boon to a very large number of shooters.
There will be an addendum to this report. I intend to mount a 10 foot target at 100yds and fire a round at each 5MOA setting (0-100) and precisely measure the distance between bullet holes. A Caldwell Dual Lead -Sled, purchased specifically for this test, will be used to aid in preci