First let’s describe what the “HK Slap” is. When the cocking handle locked back and up into a slot in the receiver, it needs to be releases. The HK slap is when the bolt handle is slapped down. Thereby, releasing it to ride forward under spring pressure to chamber a round.
This is how many of the HK guns were designed to work. There are some internet forums that discuss the HK slap and say that it contributes to excessive wear. However, in my opinion this just doesn’t make sense. Riding the bolt home to “prevent wear”.
Basically keeping the bolt from impacting on the chamber is a symptom of the thinking that causes people to ride their pistol slides forward causing malfunctions, and/or buying buffer devices that retard the slide action and cause malfunctions.
Use the gun as the manufacturer designed it and you are almost always guaranteed less problems than when you try to engineer new techniques.
In the video I was shooting some ammunition with hard primers. When I used the sling shot method of pulling the handle to the rear and letting it go, or when I rode the handle home I had multiple failure to fire malfunctions.
When I used the HK slap I did not have any problems. I know this is anecdotal, but it works.