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Filling a hollow stock

Posted: August 30th, 2021, 9:06 pm
by QuietM4
I recently picked up a Ruger American Ranch Rifle 5.56. I've owned a few of the Ruger American Rifles over the past few years, and have been impressed...a lot of bang for your buck.

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.

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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.

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Re: Filling a hollow stock

Posted: August 30th, 2021, 9:37 pm
by sonofbp
Nice, I was going to suggest spray foam lol. Your method seems far superior.

Re: Filling a hollow stock

Posted: August 30th, 2021, 10:35 pm
by tunnug
I also used the airsoft BB's but I used Silicone, I also needed a little more weight so at the end I added some lead shot, It now balances perfect and the stock is solid.
Just added silicone, BBs pushed into the mix, more silicone, more BB's and so forth 'til it was filled.

Re: Filling a hollow stock

Posted: August 30th, 2021, 11:30 pm
by QuietM4
tunnug wrote: August 30th, 2021, 10:35 pm I also used the airsoft BB's but I used Silicone, I also needed a little more weight so at the end I added some lead shot, It now balances perfect and the stock is solid.
Just added silicone, BBs pushed into the mix, more silicone, more BB's and so forth 'til it was filled.
I've got space left over to add some stick on wheel weights if I need to fine tune the balance further.

Re: Filling a hollow stock

Posted: August 31st, 2021, 4:39 am
by delta6
Great solution..cool :clap:

Re: Filling a hollow stock

Posted: August 31st, 2021, 2:27 pm
by chicoandzeus
Agree, very cool idea. I was going to suggest epoxy but was concerned about the heat generated but it looks like you covered that too! Awesome idea.

Re: Filling a hollow stock

Posted: August 31st, 2021, 2:33 pm
by Old Jeff H
Nice work! Has me wondering if I'll end up needing to do that with my 300BO version.

Re: Filling a hollow stock

Posted: August 31st, 2021, 2:59 pm
by QuietM4
chicoandzeus wrote: August 31st, 2021, 2:27 pm Agree, very cool idea. I was going to suggest epoxy but was concerned about the heat generated but it looks like you covered that too! Awesome idea.
I was slightly worried about the exothermic heat effecting the stock, but it didn't. It was warm to the touch, and I gauged it with my laser thermometer; 101 degrees F was the highest it got....stock will get a lot warmer sitting in the sun in April. After I temp gauged the first pour, I knew it would be OK to fill it up all the way.

Re: Filling a hollow stock

Posted: August 31st, 2021, 3:02 pm
by QuietM4
Old Jeff H wrote: August 31st, 2021, 2:33 pm Nice work! Has me wondering if I'll end up needing to do that with my 300BO version.
I've got enough BB's left over to cover you if you want them. 8oz of epoxy fills all up perfectly, which is convenient because epoxy tends to only come in 4oz, 8oz, 16oz, or 1 gallon sizes. Picked up the 2-part epoxy at Blick Art Supply on University and Rural.

Re: Filling a hollow stock

Posted: August 31st, 2021, 3:33 pm
by Old Jeff H
QuietM4 wrote: August 31st, 2021, 3:02 pm
Old Jeff H wrote: August 31st, 2021, 2:33 pm Nice work! Has me wondering if I'll end up needing to do that with my 300BO version.
I've got enough BB's left over to cover you if you want them. 8oz of epoxy fills all up perfectly, which is convenient because epoxy tends to only come in 4oz, 8oz, 16oz, or 1 gallon sizes. Picked up the 2-part epoxy at Blick Art Supply on University and Rural.
Thanks, man! I have a bunch of them already though from powder coating bullets.

Re: Filling a hollow stock

Posted: September 12th, 2021, 11:15 am
by 792mauser
I used duct seal putty I got off Amazon cheap