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GT's Splendiferous Labradar QD Magnetic Kinetic Trigger Mount

Ned Ludd

Silver $$ Contributor
The Labradar is a tremendously valuable piece of equipment for reloaders that consider velocity measurements a critical part of load development. Nonetheless, many of those that use the Labradar have experienced dropped shots, or having their neighbor's muzzle blast trigger the unit inappropriately.

I first became aware of the existence of an external kinetic trigger for the Labradar from posts by F Class John here at the forum. Based on his advocacy of the kinetic trigger, I decided to purchase one for myself. I purchased the same unit John described, as well as a soft plastic picatinny mount, both of which are manufactured by JKL Precision (https://jklprecision.com/product/labradar-trigger/). The only issue with which I was not completely satisfied was the velcro mounting solutions provided. I'm sure they work just fine, but I find velcro to be problematic over the long haul, and thus decided to create a quick-detach magnetic mount, using the JKL picatinny holder and a short section of picatinny rail I had lying around.

The components I used to assemble the QD magnetic kinetic trigger mount mount are illustrated in Fig. 1. The parts list and cost of each item are shown in the Parts List.

Figure 1.jpg

Table I.jpg

The magnets were obtained from totalElement (https://totalelement.com/) and the rest of the components purchased at Lowes or Home Depot.

I started with a 2.75" picatinny 6-slot rail section that had already two pre-drilled holes, a 1.5" x 1/2" x 1/4" permanent magnet, countersunk on BOTH sides, and two 1/2" x 1/2" x 1/4" permanent magnets, countersunk only on one side. The primary reasons for using two different types of magnets was to obtain plenty of grip, use the holes that were already drilled, but not have to drill more than two extra holes.

The picatinny rail segment was marked and 9/64" holes drilled using a drill press from bottom to top to secure the center 1.5" magnet (Fig. 2).

Figure 2.jpg

The 9/64" holes were then countersunk using a 5/16" bit to accommodate the small nut and washer for each screw. I used a very small file to remove any flashing and smooth the edges of the holes prior to attaching the magnets, as shown in Fig. 3. The top of the picatinny rail following attachment of the magnets is shown in Fig. 4. It is important to note that the 1/2" square magnets will only seat adjacent to the center 1.5" magnetic in one orientation without being violently repelled, which is the reason for purchasing the center magnetic with countersunk holes on both sides.

Figure 3.jpg

Figure 4.jpg
 
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Part 2

In order to minimize marring the surface of the rifle action/barrel, I next coated the bottom half of the unit (i.e. the magnets) with several coats of Plasti Dip. The Plasti Dip coating is shown before and after drying in Figs. 5 and 6, respectively. It contracts and molds itself to the surface underneath quite a bit as it dries.

Figure 5.jpg

Figure 6.jpg

After the layers of Plasti Dip on the magnets had dried, I then used a little more to fill in the countersunk holes and cover the screw nuts on the top of the rail as shown in Fig. 7.

Figure 7.jpg

The magnetic mount with the empty plastic picatinny rail mount in place is shown in Fig. 8, and is shown in Fig. 9 with the kinetic trigger inserted.

Figure 8.jpg

Figure 9.jpg
 
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Part 3

The unit as mounted to a rifle is shown below in Fig. 10. I chose to mount the magnetic holder on the barrel just in front of the action on the left side of the rifle. I don't believe it will have any significant effect on barrel harmonics so close to where it screws into the action. I have tested the magnetic kinetic trigger mount with both .223 Rem and .308 Win loads in different rifles and it has performed flawlessly. It did not move during the recoil impulse, nor miss a single shot, nor pick up any unwanted shots from adjacent shooters on the line.

Figure 10.jpg

So is such a Splendiferous QD Magnetic Kinetic Trigger Mount absolutely necessary? Maybe not, but I could, so I did. The magnets, picatinny rail sections, screws, nuts and other components were all sold as multi-packs, so anyone interested in making one of these mounts will have enough to make several after purchasing the components. Going in together with a couple friends might be a good way to reduce the per unit cost of the components.
 
Great job on the write-up!
Thanks for sharing.
To be honest, I had absolutely no idea there was a trigger like this for the LabRadar. I have a LabRadar and have had all the little hiccups you described. This will be a nice addition to a great product.
Thanks
CW
 

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