Re: UPDATE - New Product! By Snipers for Snipers!
Many of you have already discovered this, but I thought i'd share it with those that have not.
Thought I’d show you FDAC owners and other interested shooters a quick, field expedient method you can use with your FDAC to adjust or “tune” the firing solutions on the internal slide to your actual muzzle velocity. As most of you already know, the .308 version of the FDAC includes (5) slides for the 175 Sierra MatchKing, at the following velocities:
2500 fps
2550 fps
2600 fps
2650 fps
2700 fps
As seen above, there is a 50 fps velocity difference between each slide. Most users have great success with the FDAC because their muzzle velocity is very close to the slide that they’re using. So, let’s say your muzzle velocity is 2675 fps, and you’d like to “tune” the FDAC to that muzzle velocity…Simple.
Once you’ve estimated your Density Altitude, and selected the appropriate “DA” column on your FDAC, if you’d like to “add” 25 fps to the inserted slide, simply advance the slide forward to the next DA column. If you’d like to subtract 25 fps, simply degrade the slide to the next lowest DA column.
In the example below, I have inserted the 175 SMK, 2650 fps slide (this is a <span style="text-decoration: underline"><span style="font-weight: bold">METERS</span></span> slide in the example). Lets say I have determined that my Density Altitude is 1,000' DA, If I simply advance the slide until it reads +2K at the top of the viewing window, I'll have "tuned" the slide to 2675 fps.
This method has been proven to be very successful with military snipers using the M40A5’s, M110’s, Mk-11’s, and various other weapon systems utilizing M118LR or any other brand of ammunition that uses the 175 Sierra MatchKing projectile.
<span style="font-weight: bold"><span style="text-decoration: underline">This method of advancing or degrading the slide to compensate for slight deviations in muzzle velocity is also useful for other purposes, such as:</span></span>
-Muzzle velocity and/or zero shift from unsuppressed to suppressed firing modes. (Obviously this would only apply if your suppressed zero shift is very minimal)
-slight adjustment or "tuning" of a ballistic coefficient.
