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Redesigned Machine Rifle Rest

Discussion in 'Rifle Country' started by JDinFbg, Jan 23, 2021.

  1. JDinFbg

    JDinFbg Member

    Joined:
    Dec 15, 2018
    Messages:
    195
    Location:
    Fredericksburg, TX
    About a year ago I embarked on a project to build a machine rifle rest to use for testing handloads in an effort to eliminate as many variables in the shooting process as possible, probably the biggest one which is me, the shooter. In addition, I was looking for something other than my shoulder to take the recoil abuse when doing ladder tests to find the best load, which sometimes could entail shooting 100 or more rounds of ammo. I documented my effort in the following post:

    https://www.thehighroad.org/index.php?threads/my-machine-rifle-rest.866763/

    As I noted in my initial post, I put way more steel in the thing than was needed, and besides being heavy to move around (103 pounds worth), I identified through using it some things I could probably improve upon. This post shows and discusses the primary changes I made to the machine rifle rest. I salvaged as much of the original rest as possible, but ended up scrapping a bunch of steel. If I accomplish nothing else, I've at least now gotten the weight of this thing down to 64.5 pounds, still a chunk of steel to move around but far more manageable.

    My initial design had a steel-on-steel sliding mechanism and even with Teflon grease, the sliding action of the carrier during firing was not what I had hoped for. In the redesign I employed some UHMW (Ultra High Molecular Weight) linear polyethylene polymer, a low coefficient of friction material used by a lot of woodworkers for tool guides. This stuff has friction reducing qualities almost as good as Teflon, but is more durable and abrasion resistant than Teflon, not to mention, cheaper. In addition to this, I treated the steel rails with a nano-ceramic compound which seals the micro pores of the metal and reduces its friction. The combination of these two things now make the carrier slide much, much easier.

    In my initial design I just used a bolt and some flat washers for locking down the azimuth adjustment that allows me to adjust the windage of the rest to line up the rifle on the target board. My experience revealed that when tightening down this bolt the twisting action caused the azimuth adjustment to move, which made it a real pain for getting things lined up. I replaced this with a clamping mechanism that is a steel block that is captive within some small angle iron brackets and precludes any torsional force being applied to the rest.

    I also replaced the forearm rest mechanism. My initial design utilized a V-rest and a nylon binder strap to hold the forearm of the rifle and constrain its upward movement during firing. In addition to being somewhat cumbersome to set up, I believe that tightening down the binder strap probably exerted some unwanted force on the rifle. My new design has a forearm support which clamps onto the sides of the rifle's forearm, and with the leather-padded, angled wooden blocks should not introduce any unwanted forces on the rifle but should constrain its upward movement during firing.

    I have yet to test out this new design to confirm it functions better than my original design and as intended, but hope to do so as soon as the combination of my schedule and weather conditions permit.


    24-Revised Rest - Front.JPG 25-Revised Rest - Side.JPG 06-Glide Block Close Up on Rails.JPG 10-Azimuth Clamp Assembled.JPG 23-Completed Forearm Support.JPG
     
    Demi-human, Walkalong and hps1 like this.
  2. LoonWulf
    • Contributing Member

    LoonWulf Contributing Member

    Joined:
    Jul 3, 2010
    Messages:
    13,209
    Location:
    Hawaii
    Now thats a leadslead!

    Nice work! im looking forward to a range report with it, thats about as close to a railgun mount for a shoulder fired rifle as anything Ive ever seen.
     
    Demi-human likes this.
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