I recommend using the medium Limbsaver AirTech Slip-On Recoil Pad for that stock.
I recommend using the small or medium size Limbsaver AirTech Slip-On Recoil Pad for the Type97 NSR G3 and the large for the Type 81 LMG.
The medium Limbsaver AirTech Slip-On Recoil Pad should fit that rifle.
To determine what Limbsaver AirTech Slip-On Recoil Pad fits your stock please measure your stock and compare it to the template on the left side of the product page.
I would recommend using the Limbsaver Precision-fit Recoil Pad designed to be a precision fit for the Ruger American, found in the link below. Or the size medium slip on recoil pad. MPN:10551
https://www.opticsplanet.com/limbsaver-precision-fit-recoil-pad-black.html
The Limbsaver AirTech Slip-On Recoil Pad was not designed to work on AR15 buttstocks. If you still wanted to use one, the large size would be the most likely to fit.
I would recommend measuring the stock and comparing to the sizing chart below.
The Small fits stocks measuring 4-1/2 x 1-1/2 inches to 4-13/16 x 1-5/8 inches
The Small/Medium fits stocks measuring 4-5/8 x 1-9/16 inches to 5-1/8 x 1-3/4 inches
The Medium fits stocks measuring 4-13/16 x 1-5/8 inches to 5-1/8″ x 1-3/4 inches
The Large fits stocks measuring 5-1/8 x 1-3/4 inches to 5-3/8 x 1-7/8 inches
The Small fits stocks measuring 4-1/2 x 1-1/2 inches to 4-13/16 x 1-5/8 inches
The Small/Medium fits stocks measuring 4-5/8 x 1-9/16 inches to 5-1/8 x 1-3/4 inches
The Medium fits stocks measuring 4-13/16 x 1-5/8 inches to 5-1/8″ x 1-3/4 inches
The Large fits stocks measuring 5-1/8 x 1-3/4 inches to 5-3/8 x 1-7/8 inches
I would recommend measuring the stock and comparing to the sizing chart below.
The Small fits stocks measuring 4-1/2 x 1-1/2 inches to 4-13/16 x 1-5/8 inches
The Small/Medium fits stocks measuring 4-5/8 x 1-9/16 inches to 5-1/8 x 1-3/4 inches
The Medium fits stocks measuring 4-13/16 x 1-5/8 inches to 5-1/8″ x 1-3/4 inches
The Large fits stocks measuring 5-1/8 x 1-3/4 inches to 5-3/8 x 1-7/8 inches
You will want the large size pad.