OK, the 1911 and BHP have fully captured recoil springs. There's a flat surface below the barrel that can be used to press against something to rack the slide. I do believe there's other brands/models with the same design. That's not possible if your recoil spring guide rod will stick out the front of the slide with the slide in full recoil position.
Now then, last night I did run across a video featuring a "name" trainer who appeared to be using the optic to help rack the slide. No idea why he didn't use the sling shot grip.
It's worth noting that he was taking care to keep the hand clear of the ejection port. It's been 30 odd years since keeping your hand away from the ejection port has been taught. Accidental encounters of handgun parts with primers has caused cartridges to fire while being ejected, resulting in hand injuries ranging from slight to crippling*. The size of the pistols prevented a safe grasp of the slide forward of the ejection port.
Watching this, a couple of things dawned upon me.
1. It appeared that all the sample pistols were compacts. IMHO, the wisdom of mounting an optic on a handgun gets more problematic as the size of the pistol goes down.
2. This was being done as safety checks during a video presentation. If an optic had sheared it's mountings, it'd be edited out, probably with a change of handling.
3. The only figures for shock loading of a slide that I know of are of a 1911 .45. The recoil shock load is 700 Gs, the battery shock load is 750 Gs. One "G" is normal gravity. I tried to calculate the load on the screws and got really confused. I got one answer where the shear load on the screws was trivial ( less than 2 lbs), the other was somewhere in the 52-55 lb range.
Using the slingshot grip on the slide is a whole lot better for many reasons. Unless you can't do it. I'd be really, really, really hesitant to slam an optic up against some object to rack the slide.
*After bringing this back to my then employer, I had 3 people admit to such injuries at the loading/unloading barrel while in the service. Given the low pressure of the .45 ACP, their injuries caused on a slight loss of function. Not true with higher pressure cartridges like the 9 mm, 10 mm or .40 cal where crippling injury was present. Yes, they had ER photos to authenticate.