RimfireCentral.com Forums - View Single Post - Precision Plinker Stock
View Single Post
  #25  
Old 10-17-2019, 10:25 AM
Gobber
Veteran NRA Member - Click Here To Join!

Join Date: 
Dec 2011
Location: 
Herndon, VA
Posts: 
185
TPC Rating: 
0% (0)
Shoulder Attachment - Been contemplating a shoulder piece for a while that is light, but robust enough to set the rifle down on barrel up.

TLDR - Make a buttstock that is tough, light and adjustable on the fly.


And now, the rest of the story...

Background- For an earlier build, picked up a MEC shoulder attachment that is quite good.
PROS- Very robust, adjustable wings, travel and cant.
CONS- Heavy, only adjustable with wrench and made for use with a thick jacket.
The cool looking rubber nubs are not comfortable against light shirt.
Solved this with a neoprene sock.


Next was a 3D printed shoulder from https://briansamson.shop.
PROS- Great price, fits anything, light weight, comfortable, adjustable wings, travel and cant.
CONS- A bit delicate as you cannot really crank down the tension on the screws or it will crush the underlying structure.


What I realized is that my primary requirement is for a shoulder piece that can raise and lower ‘on the fly’ to various shooting positions without the need for a tool. Biathletes solve this with a solid, two position shoulder piece made for the specific standing and prone positions of competition. That is something I may toy with in the future, but it makes for a big hook at the bottom of the butt plate that will want to snag in the woods. What I want something that I can variably adjust for any position in between.

My concept is to use a cam lever to tighten a clamp fitting over a rod to allow rapid adjustment. It does not need the adjustable wings, because the shouldering surface will be fixed to a profile that works well enough for each position.

So here’s my initial concept - Use a 1 ” segment of oval CF tubing to act as an internal clamping body.
Pack some CF + resin ‘hairball’ mix around the tube to make a tight fitting interior surface.


Once cured, cut out a gap to allow some flex for clamping that can also slide past the mounting spacers.


For the shoulder piece, settled on a 3 part form that would hold the clamp in place to put three layers of 12K CF to form the shoulder section.


Here it is with the CF wetted out and clamped in place to hold the weave in place.
Lesson learned here was to orient the weave at 45 degree to better conform to the arch.


Here is the cured shoulder piece with the CF clamping sections imbedded and the excess trimmed off.


A shot down the middle after trimming to fit the rod mounted to the stock.
For this one, I lined it with brass tube to allow it to slide easier.


Here it is clamped down in the standing position.


Here it is in the higher, prone position.


It’s all pretty rough looking as I want to make sure it functions properly before trimming it down to a thinner size and sanding it all smooth.
So far, it’s not bad. The shoulder piece is tough, light and comfortable against the shoulder.
I have actually bounced the rifle butt section down on the concrete (unloaded of course) and it’s solid.
Current issue is getting the right balance of the clamping surface ‘grippy-ness’ when cranked down and smooth sliding when loosened. Pretty close, but still a work in progress.
After a bit more use, I'll add a cap to the top of the rod section to act as a stop and make one for the bottom that is screwed into place so I can remove the clamping shoulder section.

More to follow soon...

Last edited by Gobber; 10-17-2019 at 10:29 AM.
Reply With Quote