Monday, July 25, 2016

Bench Rest Benches (Or How I Spent My Memorial Weekend)

Time to give Precision Airguns a face lift on the Range.  I went through a variety of benches through the years.  Based on what I've seen and had, I decided I could build some better myself.  In my opinion, the key to what makes these benches different than any others that I have tried are the laminated tops.   After much thought, and remembering that a hollow core door can be light weight, yet rigid from corner to corner, I decided to adapt this principle to a shooting bench top and I came up with the laminated top idea.                                                                                                                      
Several years ago, I built the first top out of 3/8" exterior plywood with 1 1/2" wide filler material.  A few hours before having one of our first informal bench rest shoots, I threw some wood legs on it.  These were suppose to be temporary, just to test out the concept of the laminated top, but actually ended up using this bench for about 3 years.  It was very stable and strong. It actually performed better in my water test than the new steel leg versions I built over the holiday weekend.  More about the water test and the steel legs in bit. The wood legs are simply better at absorbing resonance than the hollow steel legs. Old woody has been relinquished to sit behind the shooting shed, it appears the squirrels and woodchucks have been working it over.
How far we've come- Early Bench Rest Set Up
Old Woody and my Theoben Rapid MKII
Back in the day - 245 3X was an average card
After purchasing a fairly expensive ($600.00 range) bench, I was extremely disappointed with the benches stability.  Oh it looked the part, had a beautiful 3/4" ply top, with beefy 1 1/2" to 2" angle iron frame underneath the top.  The bench had three legs which is common. As you know a three legged bench/stool/table can not wobble on an uneven service.  Excited to test out the bench.  Set it up, and fired my first shot using a 12fpe Steyr air rifle. After firing my first shot, I was amazed to see the cross hairs of the scope dance around.  It seemed like forever, in reality it was probably just a couple of seconds.  A heavy bench with a heavy rest and rifle, shooting at only 12fpe produces this much movement, hmmm what gives?   I was drinking a bottle of water at the time, and noticed after pulling the trigger, you could watch the bottle of water wobble and gyrate for sometime after the shot cycle.  I realized the reason it moved so much, was that the top was springy, it would easily flex from corner to corner and the screw in legs, even though beefy, they would continue to dance around with the flexing top.  This was now my go to test for testing the stability of my benches, what I like to call the harmonics water test, which is placing a cup of water or a water bottle on the bench while then thumping down or bumping in different directions on the bench to measure resonance, vibration, movement ect.  
The steel units are easy to break down for transportation should that be necessary.  Wing nuts could replace the nuts used on the cross bracing, and helicores could be installed in the bottom of the laminated tops where I used wood screws as I do not plan on transporting them often.  Two legs close together in the rear was much more rigid and supportive than three, yes in some cases it may be necessary to shim one of the legs, but not a big deal.  Again, many ways to customize this bench idea for your needs such as ambi, left hand, more mass or better yet a shelf to accept slide in weights when needed.  If not being transported, the structure could be even more rigid if the horizontal cross brace was made of the same 1 1/2" .075 steel tubing and welded in place.  The main jest of the story is how happy I was with the laminated bench top idea.  The final out come is a bench that is fairly light weight and portable, but still provides good stability, and passes my harmonic water test. 

 Tweeks or Mod's are only limited to one imagination. adding various, fillers, foams, weight, damping material are just a few ideas.  After shooting MANY cards on Old Woody, my personal best has been  250 24X.  So far my best card on the new metal legged benches with the Thomas gun is a 250-23X. Hoping more bench time will reward me with the ever elusive 250 25X.
Note: Cards were shot indoors, building is 25 yards long,
 actual shooting distance is approximately 24 yards
Target #1 "OH SO CLOSE"

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