Very nice rifle and setup!!!
I recently purchased a PTR91 GIR and decided to make it into a DMR (more like a DmR - little m) because it's heavy and although I like the wood furniture, I could only find a stock.
I purchased the wood stock and then had my heart set on a Vortex Viper PST 4-16x50, which is a little too long and has 4" of eye relief. I figured someone would make an extended butt pad for the G3 wood stock to get me far enough from the scope but to my surprise, nothing exists. There's options for plastic stocks or slip-on recoil pads but nothing that is actually made for the wood. I found a rubber butt pad for the wood but it's the same length as the original and wasn't helpful. I also tried looking for extended butt pads for other rifles but nothing I could find quite matches the dimensions and I didn't feel like buying a bunch to try.
I came across the HK21E butt pad for plastic stocks and decided that since it's the right dimensions, I would find a way to make it fit. Luckily the wood stock, sans butt pad is longer than the plastic ones and the length difference is made up in the plastic butt pad. That just helps add to the length I was looking for. The only example I could find of someone else fitting an HK21 butt pad to a wood stock is a single forum mention about someone inserting tubes in the stock for the clips to attach to. I didn't want to risk damaging the stock so I decided to adapt the pad to fit the stock. HK21 butt pads just came into RTG so I got my notification and bought one immediately!
First step is to address the way that butt pads attach to the wood stock. I decided to use the original butt pad as an adapter and sand it flat. It's some nasty fiberglass like material so I recommend gloves and a respirator. I used a belt sander to make the rear/curved side flat. Once flat, if you've scuffed the sides, it can be sanded, wet sanded and oil rubbed to get the black color back.
Next, I drilled the rivets off of the HK21 butt pad to remove the clips. Now the original butt pad is a flat adapter/spacer and the HK21 butt pad has a flat, although stepped surface. I used the adapter to mark where holes should go on the metal side of the HK21 pad and drilled some holes. Start with a small drill bit because you're on the edge of a pocket in the aluminum plate molded into the butt pad (Visit RTG to view the plates). Work your way up to the screw size which is a 10-32. From the rubber side, I ran a much larger drill bit just through the rubber and a little bit of the aluminum plate but not all the way through. I got some longer screws 10-32x7/8ish (tapered machine screws with Phillips heads), oiled them and pressed them into the pad. I also got a large 3/16 x 3.25" (I think) rubber o-ring to fill the gap made by the stepped aluminum plate in the butt pad and Viola! HK21 butt pad on a G3 wood stock! Bam!
It's not the prettiest job but it's good enough for me. Hope this helps out anyone who's wanted the same thing!
Last edited by DedPyro; 06-06-2018 at 11:05 PM.
Very nice rifle and setup!!!
OP, you do realize you destroyed an unobtanium part (the plastic butt cap) to make your adapter right?
Government exists to protect us from each other. Where government has gone beyond its limits is in deciding to protect us from ourselves.
How fortunate for governments that the people they administer don't think.
Cool beans. BTW, the original wooden stock cap is available used, just can't remember who has them.
There are also soft rubber ones available (as mentioned) on HK Parts.
I fix the radar you'all try to stay under...
I do realize that it's a difficult part to find but RTG has them in stock I believe. I wasn't aware that they were generally unobtainable though. Knowing that, if I had to do it again I would likely try to turn the new rubber enhanced one from HKParts into my adapter first.
I just got so frustrated that there isn't a good option for an extended butt pad for a wood stock. Maybe I'll look at having a few adapters made to avoid damaging originals. Think there's enough demand for it?
Have you look at the Magpul PRS tactical stock for your PTR 91? It will solve your LOP problem.
Last edited by samnev; 06-30-2018 at 04:24 PM.
Bottom line - good job, and thanks for sharing your experience and ideas.