Finally anything added to your regiment kit becomes standard issue, and so is always available. This means if you minmax the regiment creation system you can begin the game with bolters and light carapace, for which you always have replacements (at least hat is how RAW explains standard regiment kit).
Yes bolters for everyone but the only problem I see in this would be that as the bolter is only added Item not the Main weapon which come included with this regiment would still be in a thight spot to requisition ammo for their bolters. They might requisition few clips as a standard kit stuff but then they would have to ditch the light carapace.
and yeah you can start to argue that replacing las pistol (main weapon) with las carbine (main weapon) doesn't include 4 clips of spare ammo for this new main weapon so you must use points to get these 4 or something clips.
And why would Fluff be bad argument choice if your regiment has autogun as standard kit Main Weapon then that weapon is their weapon off preference and they have it, end of story. And most books Black Library has published about Guardsmen in most cases they have had las weapons. Damn even Hero of the Imperium Ciaphas Cain uses humble las pistol over Boltpistol and one shots Orks with it. Just remember even if they one shot Orks and Nids and Heretics in books and stuff they might not be so balanced if used directly in RPG games.
And checked that in every corerules Autogun has been Average availability item.
"Your team is ambushed by heretic cell and they all one shot your characters. Make new characters." NO THANK YOU!
"but im derailing from the main topic so back yo you Tom."
"Thanks Bob. And in the evening we have nice day with only 89,7% change of Heretical Insurrection."
I had imagined that replacing your main weapon also supplies the standard number of clips for the weapon. Again though it would be nice if that was specified.
And honestly I can see that you can get minimax it pretty heavily (not sure about a bolter and light carapace (unless he's talking about the best quality flak) but it is minimaxing and this is a group decision that has to be agreed with the GM it should be used to select appropriate gear not the best gear for the points and GM should feel free to deny. Sure you can spend all those points on a suit of best quality carapace armour, and If you wanted to play a regiement with carapace I'd be fine with it, but having a unit equiped like that without even a microbead between them and no respirator or photo visor, they are missing a lot of really important kit because of it.
As for Autoguns, I'm completely fine with it, Lasguns are the absolute standard weapons, I can't think of one regiement from the background or stories that has an Autogun as standard. But if you want it for an affectation, that's in the rules, fine, so it costs some points. Just like the Vostroyans forked 10 points for best quality Lasguns or the Elysians were taxed 10 points for combat shotguns, which, like the autogun, are inferior to lasguns are most ranges but devastating up close. I can see rules being used, a custom hive world, a special regiment type that made it cheaper or allowed it straight off, and there may well be in a future suplement, but it's not at all out of the question at the moment.