(23-6)*1.75= 29.75 is what we are looking at.
But like MadCat, I would load HP on automatic weapons since those enemy are quite fast.
Yep. DT has a bite out of damage before multipliers are applied. That's one of the many reasons energy weapons svcked early on: they had absolutely zero means to reduce DT. Powering through DT that was too much for normal rate cells was impossible.
I like long-range sniping better. The closest I've gone is Cowboy Repeater. There's Sleepytime but I mostly use it in urban combat interiors.
How reliable is Service Rifle? I'm talking about its effective range. Thing is, I don't have Trigger Discipline, and to make matters worse I have Small Frame (and haven't taken Adamantium Skeleton yet). I can't afford close-range combat.
Not having Trigger Discipline is a good thing with the Service Rifle, as its advantage is in volume of fire. It's not gonna be shooting ticks off of brahmin asses at 100 paces, but it has a tight enough grouping if you are adequate in Guns skill. Volume of fire only becomes greater once you get the spring weapmod for it, and it'll handle wear and tear better with the receiver mod. It'll be a good weapon for when the brahmin pie hits the fan, precision is out of the question and you need to kill them with sheer volume of fire. If you have PC and WMX, you can stick an extra-length mag mod on there (26 vs 20 unmodded) as well.
IIRC, if you do a favor for some ranger at the Mojave Outpust all the way in the south (kill giant ants IIRC), you get a Service Rifle and a few mags' worth of AP ammo.
Always have options. My preferred play style is to snipe with a http://newvegas.nexusmods.com/mods/images/43132-2-1312504522.jpg (the "POWWwwwww-ka-chink-chink" is much more satisfying to me than some silenced gun that goes *phoot*), but when the going gets tough, the tough bust out a http://newvegas.nexusmods.com/images/115378-1298506600.jpg and let the ozone smell waft over the scuffle.