I've almost always used birch , I thought it was easy to work with .
in a 22 , i'm curious how cedar might work as a core , then add a couple layers of fiberglass to the outside for durability .
or even strands of cedar fibre bonded together with a fiberglass resin .
It works very well. It is almost as light as dense foam. Not really but not enough weight difference to notice. I did one with a fiber blanket wrap done with strips about six inches wide and wrapped around the wood one strip at a time. I roughed up the stock with 60 grit paper first and applied a coat of resin over the wood and laid out the cloth on it one bit at a time. I cut each piece on the bottom of the stock so there wouldn't be any fibers sticking up. A one inch wide brush laid the cloth down on the primary resin coat very well.
Once the stock was fully coated and allowed to dry overnight I added another coat of resin that contained dye to get the color I wanted. I should mention, I had previously inletted the stock on the milling machine.
After three coats and a good sanding it was very smooth and ready for the final spray coat. This was done at the local boat shop. The fellow that did it is an artist when it comes to finishing fiberglass.
The rifle that went into the stock was a Remington 700 long action chambered in 338-06. I opened up the inletting and roughed up the wood so it would hold the resin well and set the barreled receiver, mag well and trigger guard into the resin used for the bedding.
It worked out very well. I wish I still had that rifle. A very close friend has it in Burns Lake and it is his go to Moose Rifle. His son wants it when the time comes to pass it on. The only issue I can see is the Cedar soaks up resin prodigiously. I found out later with another build that it was easier to thin down the resin and apply it in quantity. It worked much better that way and made it easier to attach the cloth. Also, there are a couple of different types of cloth out there. My first build used a woven cloth with coarse/heavy weave. The next one used a cloth that was much smoother with a fine weave and the last one was more of a matte with no real pattern. The fine weave was the best IMHO, while the matte made for a thicker/heavier cover.
Don't get me wrong, you don't save any time by making up a Cedar stock and covering it with fiberglass. However, the combination gives you a very light/strong/stable platform.
In case I forget to mention, I also used cloth/resin in the barrel channel as well and sanded it to size with a drill mounted drum sander covered with sleeves. A bit of care must be taken here to make sure there aren't any gouges from the drum edge. Once you have gone deep enough to free float the bbl a thin skim coat will finish it off nicely.
If I were looking to build a very light/tough/stable stock again, for whatever reason I wouldn't hesitate to do another. IMHO it is as good as any of the expensive commercial alternatives. Remember, the Cedar should be laminated. The Robertson Micro Precision stocks are made out of a very light material that appears to be ash which may or may not be as strong or stronger than Cedar. I did a build with one of those excellent stocks and didn't notice any real difference other than it was heavier than the Cedar.
These days, I am just to lazy to start from scratch and take a couple of weeks from start to finish on a stock. I am also less financially challenged than I was back in the day so I now will usually pick up a Boyd's stock for a build or modify a take off stock found at a gun show. The new Zytel stocks are very difficult to work with as far as modifying or bedding goes. Now, if I am getting serious about a build I will make up an aluminum bed to mount the rifle and mount the bed into a Zytel stock that has been milled out to accept it and fill it with resin. Even then, it doesn't always work.