a fully extended chassis on rails in a wall mount anything (frame or enclosure) is going to place an extreme amount of pull force on the wall attachment points.
I would personally not place anything but a static, fixed load into a wall mount.
equipment on rails is a lifesaver and, if you really want to do it, consider a freestanding enclosure thats designed to take deep servers, extended loads and has anti-tip features.
I guess that’s a very valid point. The racks is bolted into concrete with 4x 5” lag bolts FWIW, so I just kind of assumed that’d be fine? But I supposed physics may not be kind to me, considering me hefting the machine into the place is already heavy…
lag bolts into shields into concrete may be secure if its done really carefully. it still leaves possible issues with the frame integrity - there are quite a few low quality frames and cabinets out there and mechanical stress on those vertical rails and all of the connection points in-between when equipment is extended on rails is no joke.
I am used to datacentre grade mounting gear (even in my home lab), so I am a bit spoiled. however... take a look at Rack Solutions for harder-to-find quality mounts, rails and adapters. a source for excellent quality steel open racks/frames and enclosures is x-mark (now owned by belden). thats the stuff I use for myself.
edit: as was mentioned in another comment, OEM rails are almost always your best bet, however high quality 4-post sliding shelves have saved my butt on ocassion. Rack Solutions also offers those.