The weak aspect hand placement works with no Particular thumb rest. Thumb relaxation from Ronni will work on MCK if you want. Shoulder strap attaches on possibly. No pistol brace extension necessary. MCK makes use of pistol's slide launch so no mal-features like Ronni. The one thing the Ronni has https://hectormyive.blogsidea.com/32090848/recover-tactical-an-overview