I heard the original G40 slide width was the same as the G36/G41. This is evidenced by the Glock website that clearly shows the G40 and G41 to be very similar in this regard. Yet, I see You tubes showing what appears to be a G20 thick slide. Has there been a design change after initial release, and do all the aftermarket barrels fit both? https://us.glock.com/products/model/g40gen4mos Batts.