Shoot 22LR in your HK91 or HK G3. H&K actually made the HK91 conversion kits for the HK G3. Full article and guide can be found at The Rimfire Report at (copy and paste the link) https://www.thefirearmblog.com/blog/2022/02/07/rim fire-report-hk91-conversion-kit/ This is a very rare and hard to find conversion kit. The HK91 conversion kit consists of a drop-in bolt and barrel adapter. It is an 18″ long sleeve that slides down the factory .308 barrel. The wider chamber part has a steel ring that acts as a friction lock so the barrel does not slide back under recoil. The HK91 Conversion kit comes with two 20 round magazines. TEXT-208-880-8450 (please use the "My Other Listings" button to see more ammo deals)