May 12, 2010 · Here are a few of the aftermarket rear sights available for the K-31. The Furter replaces the entire leaf and is adjustable for windage and elevation. The Sahli is elevation only. The Grunel is both front and rear sight assemblies, windage and elevation. Now with the advent of the new Adjustable Front Sight, even the old Type P's and PIIs will achieve the 1,000 yard ability. The new P11 Diopter series will use the 1911 Clamp-On-Mount and work with the 1889, Kadett, 1896, 96/11, the G11 and the K11 rifles. The new P11 is also a 1,000 yard system.Diopter sights, the DIY method. I love restoring beautiful things. At times it involves me making missing parts or altering. This was the case with a Falke 80 .177 I recently acquired.. No sights, trigger-guard, trigger sear made from aluminium ad nauseum.