dawico,
Over the years, I've loaded shot shells with the old LEEs manual loaders (45+ years ago) and modern progressive presses. With plastic wads, sizing and wad pressure are not an issue. Once you get the wad past the mouth of the shell, just seat it on the powder.
Reloaded shot shells typically exhibit only a few problems: The first is sizing the brass (or brass wannabe) base, many loaders omit this part. For many years I didn't size my 12-ga brass and used my reloads between several O/U guns; however these same shells would jamb in my auto loader. This is one reason folks trade in their MEC 650 for a Grabber model. The 650s don't automatically size the brass; but, many one gun shooters don't need re-sized brass.
The other general problems have to do with crimping. Hand crimps are often not forceful enough to stay closed. Many reloaders have put perfectly good looking shells in the box only to later find the crimps have opened and spilled shot. You may hear hand loaders talk about using sealing wax, or other methods of cementing their crimps closed.
The other problem associated with crimping is bulging. Modern loader's dies maintain the outer diameter of the shell while crimping, this is not the case with hand loading. It may be just the perspective of the picture, but if you look at the OP's reload, it seems the top of the shell bulged a little while being crimped. The bulge may prevent the shell from easily chambering. You can often coax them into a hinge gun, but they will jamb in a pump or auto-loader.