Oh man that anachronistic goodness is part of the Spaghetti Westerns charm and essence, as opposed to say the Ford/Waynes getting everything more historically accurate, but so aesthetically wrong... IMHO.
And don't forget the big one... belt loops on trousers weren't in place until turn of the century... find a Spaghetti where a principal doesn't have a regular belt under their gun belt. The SASS, and other aficionados, freak out about this, but screw them, multiple belts look so damn cool, and just feel right, I don't care if it's not accurate, that's not why I'm watching. These are mythological characters in a folkloric tales with magick weapons and abilities. Bring on the strangeness... now where's my polyhedral dice?
Anyway, back to cool hardware, the Mauser is still an insane weapon choice for a western, thrown in purely for gimmicky (and/or holy grail) effect. And while Fistful trades fantastical weapons for supernatural marksmanship we still get a lot of screen and dialog time dedicated to romanticizing Ramon's rifle - and one could argue Fistful employs "magick armor" - keeping it right in that wonderfully weird Spaghetti vein. As mentioned, by the time we hit Few Dollars More the gimicky weapons are in full effect.Tuco's erector set scene in the gunstore, in GBU, completely bananas, but oh so cool.... and still "in the ballpark". Excalibur? Mjölnir? Stormbringer? What's not to love? The fact that Spaghetti's dared to flirt with these concepts, regularly, is a big chunk of what makes them "sub genre".
How the vast majority of Spaghetti Westerns blend fantasy with the western (however subtle, or not) and still manage to not fully jump genre is just brilliant.
If you are not suspending disbelief when watching a Spaghetti, in the same way you do for say a one-arm swordsman jumping backwards into a tree, or a bowler hat that can cut through stone, then you're probably parked at the wrong drive-in.
Here's a weird thing, but somewhat on topic. I love how in a lot of the spags there is someone else who carries a main characters weapon... Fistful and Django come to mind but there are dozens. Like when a little weaselly character hands the villain his rifle before he shoots someone... this is so Arthurian right? A squire genuflecting and handing their master a legendary weapon. Ever notice that? Love it.