Because of this thread, I got a couple of BulletButtons for my SP89 and HK43. After fiddling w/Radlocks on both, I was glad to have a product the HK's deserved. Top quality design and materials. Be sure to get the $5 tool for the snap rings.
Also, a big thanks to Darin for cleaning and installing the ten round limiters on both mag part kits. What a great company!