My only rear gripe has been the cheap-feeling stock. Inexpensive, hollow plastic...it functions fine, and I know it's how they keep the cost down, but I'm not a fan. Savage has the same problem as well...an FV-SR I have had the same issues...I fixed it by buying a Boyd's TactiCool stock.
Now that I have another Ruger, I wanted to fix the issue. Since this rifle takes an AR-15 style magazine, there really isn't a viable stock alternative on the market that I like. KRG, Magpul, and other chassis systems force you to use AICS pattern mags, and one of the main reasons I bought the rifle was because it uses AR mags. Besides, AICS pattern mags that accept .223/5.56 kind of suck.
Also, once I built up the rifle and added my old Surefire suppressor, the gun became very front heavy. So, I needed to balance out the rifle as well as get rid of the hollow sounding stock. Googled around a bit, found a lot of other people have the same issue with the stock...wanting to get rid of the cheap sound. Others have stuffed shop towels, garbage or grocery bags into the stock, but that doesn't solve my weight balance issues....and it doesn't work well for the sound mitigation, either.
My first thought was to add motorcycle wheel weights to the inside of the stock...they have a sticky back that won't come off easily. Balance solved, not the sound.
Next, I came up with filling it with expanding spray foam. Others suggested it online, but spray foam can be unpredictable and very messy. For weight, I thought about adding BB's or lead fishing weights into the foam, but that may be difficult to evenly disperse.
Eventually, I came up with my solution. Airsoft BB's mixed into suspension with epoxy resin. The BB's are uniform (6mm in diameter), don't add too much weight (0.12 grams each), and can fill up a large volume while adding weight in an easily predictable way. Steel BB's are too heavy, and would just sink to the bottom in the epoxy.
After some 8th grade Advanced Geometry mathematical calculations, I was able to work out the volume of the stock (filled it with water), and the amount of BB's needed to fill that volume. 8oz of 2-part epoxy to fill in the gaps between the 2,200 BB's, and problem solved. Epoxy doesn't expand, so it's the perfect medium for this application.
Overall, it cost about $28. I mixed and poured the epoxy/BB mix in two stages so it wouldn't generate too much heat, just in case the stock didn't like it. Now the rifle balances perfectly...plus, I'll get a little recoil reduction as a bonus.
