New DIY lightweight stock

[chalkeye]

Thought I might document the progress I'm making on a DIY stock.

As everyone else already figured out, the hogue stock that came with my Howa 1500 was really floppy and heavy.
I'd always sort of planned to build one myself, so this was a good excuse to start experimenting.

This project is already 3/4 through, so forgive me if my recollection of the process is a little bit piecemeal.

The first job was bedding & stiffening the hogue, which made a dramatic improvement, particularly to shooting from a bipod.
Heavy though:

Over a kilo, and pretty ugly. And plastic. And common.

 

[chalkeye]

I started with modelling up the action I had, then converted this into a cutting volume - a digital plug I could subtract from any stock design to fit the howa metal:

This keeps the stock design separate from the action, and means I can tweak the action cutter throughout the prototyping without affecting the stock, and vice-versa. It also means I can theoretically make up another for a different action, and drop it into the same stock design.

This is the oldest concept I can find:

The important bit of this design was to split the stock in half. I originally looked at carbon fibre, but rapidly ruled it out due to it being a massive dick to work with, and difficult (and expensive) to make progressive changes.

Splitting the stock in half, has a couple of huge advantages:

1. The inletting can be machined in one hit from the inside
2. It can be hollowed out, and made significantly lighter

I dropped the idea of the carbon fibre foreend pretty quick, but the idea was that it could be a single cavity mold.

 

[chalkeye]

Redesigned the process & stock to remove all the dicking around difficult, expensive materials:

Ultimately this means some expensive, difficult dicking around with a CNC, due to having to re-datum the material once you've flipped it over. Nothing wildly challenging though.

I also started getting too excited at this stage about how it would look if I spent another thousand bucks on rifle accessories too:

You can see here the lattice structure I looked at for the butt. This area represents the largest unnecessary volume of wood on a traditional stock - though many are bored out, there's still a heap of material that doesn't need to be there. If you look at the area through the pistol grip, this is the most narrow part (and most common failure part) in the majority of rifle stocks, so all that extra mass does nothing.

Similarly the forend doesn't need to be super solid, as it really only serves as a resting surface or bipod & sling attachment point (when you have a floated barrel).

That was my thinking anyway, so I pressed on with making up some plywood blanks for the first prototype. It proved remarkably difficult to find a competent CNC routing guy who could work with 3d files, but eventually it got underway:

 

[chalkeye]

The weight of this 1st prototype is about 2/3 that of a full wooden number (by volume), if I recall correctly. Putting this one on the scale is right about 500g (with recoil pad, pillars & new trigger guard)

There were a number of issues with this design, some which were expected, some not:

• I got the palm swell bit really wrong - this required a fair bit of filing & adjustment. Unfortunately this resulted in breaking into the internal void - not a huge issue, as the inside is sealed before the halves were glued together.
• The foreend was REALLY hollow - fine as far as deflection & stiffness, but it had the result of resonating when you cycled the bolt
• I also screwed a sling stud into this, which obviously ripped out after not very long
• The LOP was a little short, so I added a big dumb heavy bit to the back
• The comb height was too low - something I reckon I should fix with the stock design, rather than the rough foam & tape solution

So, on with redesigning for the P2 prototype:

 

[NW Hunter]

I am enjoying watching the process. Keep us posted.

 

[HARPERC]

Folks with such skills alway impress me! A good honest review, and plan.

 

[chalkeye]

 

[shortgrass]

watching...........

 

[ejg]

Very interesting, I like your approach. 500 grams is fantastic.
We have achieved 560 grams in a monocoque carbon construction hunter type and 790grams in a tactical/FTR stock with a cheek raiser. A lot of attention to detail is needed.
edi

 

[chalkeye]

Very interesting, I like your approach. 500 grams is fantastic.
We have achieved 560 grams in a monocoque carbon construction hunter type and 790grams in a tactical/FTR stock with a cheek raiser. A lot of attention to detail is needed.
edi

Your stocks are really nice! I was surprised at how little difference there was with carbon stocks when I started removing volume from the timber design. The expense and difficulty of working with carbon was a real turn-off for me, but perhaps in the future there is an opportunity to have a go - a hybrid with wood would be very interesting.

I do wonder how much further a carbon stock could be pushed, design wise - using unidirectional fibers and really strictly controlling the resin ratio etc. Failures might be a bit scary though!

 

[chalkeye]

Fitted the dowels, finished the bulk of the inletting (I thought) and sealed the inside:

Gluing the two halves together, always a bit scary:

 

[ejg]

You are almost done, great.
What do you normally manufacture in your workshop? seems well equipped.

We do have an internal unidirectional carbon frame in our stocks as well as an internal frame around the inlet/recoil lug/internal pillars. Woven carbon outer shell, lightweight fill in the front and rear cavities all wet in wet laid up in one go. As far as we have noticed the dangers or limits are that the carbon shell or in your case a thin outer wood layer could be punctured if the stock whacks against a sharp object. No total failure. Stock stiffness I think is very important, going extremely light the stiffness will go down to a level that one might not be happy with. As usual it's about finding the right compromise.
edi

 

[foreign]

hey chalk

good to see this on ere as well as nz unter. im Rob hughes-games on there. nice work on the stock. i have to learn how to draw like that in solid works

 

[chalkeye]

You are almost done, great.
What do you normally manufacture in your workshop? seems well equipped.

We do have an internal unidirectional carbon frame in our stocks as well as an internal frame around the inlet/recoil lug/internal pillars. Woven carbon outer shell, lightweight fill in the front and rear cavities all wet in wet laid up in one go. As far as we have noticed the dangers or limits are that the carbon shell or in your case a thin outer wood layer could be punctured if the stock whacks against a sharp object. No total failure. Stock stiffness I think is very important, going extremely light the stiffness will go down to a level that one might not be happy with. As usual it's about finding the right compromise.
edi

I'm an industrial designer for an appliance company, so we have a decent shop.

I'd love to see some pictures of your set-up, if that's possible? Specifically how many cavities/forms you use for molds, and how you stick them together!

Foreign, good to see you - all the rendering is done from STL files in Blender, but the modelling was done in SolidWorks.