I really have no idea why people have this fetish with a rifle designed to be carried, used and serviced by illiterate peasants (the Mosin).
I’ve heard people rave and bluster about them... and I remain completely unimpressed.
For a bolt gun, people could do far worse than to pick up an old Springfield 03A3.
As for the Mossberg 500... it works OK, I guess, but it’s a really cheap piece of crap. The plastic trigger guard and the balanced springs in the trigger group (a real potential for failure there after detail stripping & reassembling it), plus the fact that they’re covered in burrs on all the machining... makes it one of the least impressive shotgun offerings, IMO.
In a pump gun, I’d much rather have a Winchester model 12, or a 97, or a Browning A5 (or clone).
The ‘03A3 is great, and I recently saw a Gibbs Rifle Co. repro of the ‘03A4 WWII Sniper that was very nice (complete with a knockoff of the Weaver scope) for $825.
You’re right on shotguns too. I’m a big fan of the 12 in 16 gauge, the ‘97 is a true workhorse, and the A-5 is a brilliant piece of design. I have one from 1914 that works great.