The Tikka T3 comes with a decent factory stock. One annoying thing about it is the large cavity in the stock that makes a lot of noise when hit by branches while hunting. Some others have filled it with plastic shopping bags but I was concerned with rain collecting in the stock so I decided to fill it with flexible expanding foam
Step 1: Remove Stock
remove your stock from the rifle. next remove the recoil pad with a Philips screwdriver. putting a drop of soap on the screwdriver will help it go through the holes on the pad easily. my tikka had a plastic grid insert right behind the recoil pad, but I don't know if older tikkas have this. remove it for now it will make pouring the foam much easier. next remove the cap from the hand grip. this seemed to be the easiest place to pack the handle with plumbers putty. you must put something in this area of the stock to prevent the foam from expanding through it and into the action area. I packed the plumbers putty flat with the handle of a wooden spoon.
Step 2: Setting Up for the Foam
to avoid making a mess from any overflow I used a old Tupperware container. I used screws the same size as the screws for the recoil pad to hold it down firmly to the stock and give a flat finish that won't require a lot of trimming. I also put the plastic grid back in the stock to see where I should place holes for the foam to escape from. this will also create some back pressure that will make the foam fill all the voids in the stock but won't be enough to dislodge the plumbers putty. everything fit well so now it's time to take it back apart and mix the foam
Step 3: Mix and Pour Foam
I had some Smooth-on brand flexible foam from a previous project and I thought it would be perfect for this. I think spray foam insulation would be a poor choice. it expands greatly and cures pretty ridged. I've heard of it springing door and window jambs from people using to much. and I don't want to distort the stock so flexible foam seemed like the better choice. it can be purchased in different expansion levels. smooth-ons website says my foam expands x10 so I guessed how much space was inside the stock and measured out equal parts of the foam. it has a 50 second pot life so I mixed it as fast as I could and poured it into the stock. I had to work fast to get the Tupperware screwed down tightly to form a good seal. I placed some tape over the screws just in case the foam adhered to it. by that time the foam was shooting up though the holes lol. apparently i estimated the amount of foam needed poorly! luckily it didn't drip over the Tupperware.
Step 4: Reassemble Stock
after waiting the 2 hours for the foam to cure I was able to easily pull the loaf of foam away from the screws. a tiny amount of foam escaped under the container but I had the stock masked off well and it came off with the masking tape. then remove the plumbers putty with a screw driver to reach into the grip. the putty stayed in place perfectly and no foam got by. then all that was left was trimming the nibs made from the expansion holes flush and screwing the recoil pad back in place. it turns out theres a small recess on the stock for the recoil pad to fit in for a nice finish. in order to get it back flush in the recess I screwed it down as far as I could then tapped the pad with a mallet compressing the foam and allowing the pad to sit flush to the stock again.