Idk, I just feel like its a NV weapon, if no body else think that's the case we can add it. I won't argue, we need something.
I'm with Steve. The Varmint Rifle is very much an NV weapon, and can't be our low-level weapon in the CW, not JUST because it is a very obviously NV weapon, but because it would throw off ammo balance dramatically. Since the Varmint Rifle runs off of 5.56, you'd get a wealth of that ammo on low levels, where in vanilla FO3 most players had to wait for about level 8-10 before 5.56 weapons became really maintainable. The only way the Varmint Rifle would fit is if it still ran off of .22LR, which would be a change to both NV and FO3 that's a little drastic for our main file. That also doesn't handle the issue of Super Mutants, who can use the .32 HR but NOT the Varmint Rifle. That would, again, be a drastic change we might not want to make.
As far as .32 ammo goes, I rather like it. Yes, the .32 Pistol (which, side-note, I think needs to be renamed the .32 REVOLVER) is a piece of crap, but its prevalence in the hands of Raiders means it provides ample ammo for the .32 Hunting Rifle, which is not crap. I dunno about you, but I used the .32 HR (and Ol' Painless) well into the middle-late parts of FO3. I'm not alone in that either. It's a key weapon role in FO3, one that can't be replaced with the .308 version due to the damage difference, and (again) the effect it would have on ammo availability. You think too much 5.56 too early is a bad thing? Imagine a wealth of .308 available to anyone from the start of the game. All you'd have to do is grab a Sniper Rifle from the Hollowed-Out Rock near Megaton and be set for the rest of the game.
Now as far as the duplicate-appearance Hunting Rifle thing goes, there's not much we can do about it. We could try and make a new shape, but that would probably be too "non-vanilla". We could use the FO3 version of the shape, but the only difference with that is that it is missing the Iron Sights completely, which frankly is not a good change. Honestly, my inclination is to just go with it. I mean FO3 didn't have unique skins for their unique weapons, so this wouldn't be too much of a stretch.
Anyway, big wall of text. TL;DR - Keep the .32 ammo, because there's no way the roles that the few .32 weapons fill can be replaced with anything from NV, at least without upsetting the balance of the game.