HW77 vs Diana 48

A kit from Air Rifle Headquarters will shoot nicer and cock easier. His VRT kit tones it down a bit and shoots very nice.

The Vortek is oversprung IMO, as are most of his kits. And the steel outer guide is known to cause issues. Wouldn't be my choice by a long shot.

As far as the comparison between the HW77K and the D48:
1) the D48 is nicer to put a sling on. And it's more powerful.
2) the 77K is nicer built and better performing in basically every other way.
3) every .22 Weihrauch I've had (quite a few) had a piss poor barrel. The .22 Diana's I've had have been nicely accurate.

If you HAVE to have a .22, get the D48. Anything other than that, the 77K would be a better choice IME.

A D48 in .22 running about 16fpe with the VRT kit is an excellent hunting gun and very easy to shoot, however.