I'm looking to fill some of the areas between ribs in a Tikka plastic stock so that I can create a nice hardspot to mount a T-nut for a bipod rail. I'm thinking Devcon would work, or would you recommend some other type of epoxy/filler combo? If Devcon, would the liquid (10210) be better than the putty (10110) to make sure there are no voids?
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Gunsmithing Plastic Stock Filler
- Thread starter WarDamnRockets
- Start date
I would think the devcon liquid would be easier...just mix up a bunch in a solo cup and pour it into your stock voids. I would make sure there is no stress on your stock when adding the devcon, so it doesnt cure in an odd shape (twisted/clamped/etc) It will add some weight to your foreend if you do the entire stock.
Agree with mcameron. This is not likely to make you happy in the long run. Specifically, you are going to be able to flex the rest of the stock and your mod either has to try to be flexible itself, or needs to be rigid in a way that won't allow it to delaminate from or damage the stock. It may also have second order effects. Seen hacks like this allow for the stock to contact the barrel, restrict feeding, or no matter how careful: crack the stock as it's not designed for the load.
If you want, then several approaches I'd consider, least to most strong, lightest to heaviest:
And other hints:
If you want, then several approaches I'd consider, least to most strong, lightest to heaviest:
- Epoxy and pray – Use G-Flex if you think just gluing in the item will do. No other epoxy I'd use in this location.
- I just noticed the stock is polypropylene. This is a not happy material to glue. Not 100% sure G-Flex will do it. Some minor research indicates this stuff is suitable for it, but it's weird and expensive: https://www.3m.com/3M/en_US/company...-Adhesive-DP8005/?N=5002385+3293241357&rt=rud Note that it will glue to other materials, so no problems.
- Back it – Do not just rely on the nut bearing against the plastic, and being held in with the glue. What we're doing is making a washer, but the location isn't suitable for simply a washer, so you want the largest flat plate you can, and it must be rigid enough it won't bend. A plate nut with corners cut off might work. Or get a U-channel of aluminum wide enough to fit the nut, and cut to length, drill a hole. Position. Glue the Al down.
- Fiber Reinforce – Use fiberglass resin. The fibers will reinforce the area you put the glue in, and you can fill the space between the reinforcing plate/channel and the reinforcing ribs of the stock.
- Insert a block – Cut something at least as strong as the stock (plastic, phenolic, aluminum) and insert it into one of the reinforcing voids. Make it close to the final size, and epoxy it in. NOT WOOD, as that will expand with water and could crack the stock. Drill a recess for the nut, of course.
And other hints:
- Do NOT cut through any of the reinforcing ribs! Drill the hole between some.
- Drill carefully. For this, I'd use a step drill as for sheet metal. It'll gently cut a hole. Twist drills will cut polygons, and can be violent to the backside.
- Surface prep! At least degrease like hell. Denatured alcohol at least, ideally also roughen up. Bad area, so if I could I'd sandblast the void where you are doing this.
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Re: new stock
That’s the eventual plan, but not in the budget anytime soon. I have everything else available except for filler/adhesive, so I want to try to make this work, even if it isn’t the BEST solution. Plus, I like to tinker.
@shoobe01, lots of great options, and some things I didn’t think about regarding local reinforcement. I might try to see what size washer I can fit in the void. That might be enough.
My thought behind filling only the front set of voids is that it won’t cause the stock to flex any MORE than it would normally. I’m a structural engineer, so I know a bit about deflections/stress, but haven’t really done much DIY on my rifles. I’m thinking that as long as I don’t fill over the current ribs, then counterbore for the nut, then potential stock contact under load won’t be any worse than if the voids were un-filled. I’m really more concerned with nut tear-out due to the thin web of plastic between ribs.
As far as the epoxy goes, I’m thinking I might key into the plastic some to try to create some mechanical lock between the filler and stock.
That’s the eventual plan, but not in the budget anytime soon. I have everything else available except for filler/adhesive, so I want to try to make this work, even if it isn’t the BEST solution. Plus, I like to tinker.
@shoobe01, lots of great options, and some things I didn’t think about regarding local reinforcement. I might try to see what size washer I can fit in the void. That might be enough.
My thought behind filling only the front set of voids is that it won’t cause the stock to flex any MORE than it would normally. I’m a structural engineer, so I know a bit about deflections/stress, but haven’t really done much DIY on my rifles. I’m thinking that as long as I don’t fill over the current ribs, then counterbore for the nut, then potential stock contact under load won’t be any worse than if the voids were un-filled. I’m really more concerned with nut tear-out due to the thin web of plastic between ribs.
As far as the epoxy goes, I’m thinking I might key into the plastic some to try to create some mechanical lock between the filler and stock.
Ah, good. Getting the gist of stresses helps. Many I talk to wouldn't get why, for example, there are ribs in there 
If you haven't seen any, find some high speed photography of guns flexing under firing. Some weird stuff may happen, with a lot more flexing than just loading the bipod, etc. so plan for that as well.
Also didn't say as far as the modification vs purchase: but if planning /sometime/ on upgrading the stock, or selling the gun entirely, make sure the changes you make to this stock won't impact the sale price or make it un-sellable. It's a consideration.
If you haven't seen any, find some high speed photography of guns flexing under firing. Some weird stuff may happen, with a lot more flexing than just loading the bipod, etc. so plan for that as well.
Also didn't say as far as the modification vs purchase: but if planning /sometime/ on upgrading the stock, or selling the gun entirely, make sure the changes you make to this stock won't impact the sale price or make it un-sellable. It's a consideration.
I am not sure I would be overly concerned about the epoxy having a mechanical lock to the stock. Basically a mild layer of epoxy would act as the washer would it not? And then you would have the clamping force of the screw that will keep it together
