Stock Shims For Winchester SX4 Shotgun

I thought I would share this in case anyone else needs to shim a Winchester SX4 for proper fit. Note: AFAIK this only applies to plastic stocks as I have not examined any with wood stocks and don't know if the same shims would work.

My SX4 already had cast built in for a right-hand shooter (there was a small ridge molded into the front of the stock where it contacts the receiver) but I also needed to add drop to lower the comb.

After searching all over the web, including several gun forums, I found that not only does Winchester not offer shims for this model but it seems they had stopped providing them with later shipments of the SX3. Knowing that the dimensions of the SX3 and SX4 were fairly close I decided to try and adapt an SX3 shim (#3R).

I started by filing off the narrow factory ridge to gain a wider bearing surface for the shim. The inside of the top part of the shim (see photos) is a near perfect fit on the SX4 stock but material needs to be removed from the bottom section. Careful clipping with a pair of flush cut diagonal cutters followed by a jeweler's file created a good fit. I had to remove quite a bit of material in the area of the trigger housing (the SX4's is wider). The only flaws in the finished part are that cosmetically there is a slight gap at the bottom of the grip (the SX4 grip is taller) and removing the center section might make the bottom prone to sliding out somewhat under recoil. I solved the latter issue with a couple dabs of de-bondable glue that I allowed to cure before bolting the stock back in place.


One other thing I did for cosmetic reasons was file and sand off the "corners" where the curved top meets the sides to match the more rounded shape of the SX4 grip. The final result is not only quite good cosmetically but now when I throw the gun to my shoulder my eye is right where it needs to be.

I thought I would share this in case anyone else needs to adjust cast and or drop on an SX4. So far I have found the latest model of this semi-auto Super X line to function 100% reliably with every load I have thrown at it. For a guy who grew up with walnut and blued steel I am actually growing fond of this modern gun with its utilitarian black finish, as it gets the job done with little fuss.

PS: In case anyone thinks the photos look odd it's because they are actually scans of the shims.

Hi Scott,

Do you have any pictures of the shim fitted?
Looks like I will have to be doing this to my Wife's SX4 as well.

This shows the general fit with a shim installed. As you can see, there is a slight gap at the bottom since these were actually made for the SX3. Also, remember that these (AFAIK) only work with the synthetic stock.