The mighty .338 Lapua Mag. This is how I would balance the sniper rifles in a shooter. All of the battle rifles could easily be built to be DMR, but they would never have the lethality of a true sniper rifle. The idea here is to take out the run and gun sniper stuff we see. They basically have a one shot kill gun but they use it like an assault rifle. By making the gun virtually useless on the move (or while in any position other than prone really), that problem is solved. On the flip side of the coin, the gun is very useful when used properly - prone gives the player perfect stability since the bi-pod will be deployed and kneeling is better than standing). Essentially there would be so much movement while using the gun standing, and even more while moving, AND finding the target again after taking a shot would take far too long to be useful; that no one would be successful using it for run and gun.
Something that always baffles me is when video game designers somehow conclude that the .308 sniper rifle they put in the game is more powerful than the .308 battle rifle they have also included in the game or that they magically hold fewer rounds than they should in order to balance out the score card. Then of course we have the .50 cal rifles that mysteriously don't do the kind of damage that they actually do. They apparently believe that a person would actually be able to continue fighting after being hit by a SEVEN HUNDRED grain projectile. Or that body armor actually protects from .50BMG. Same goes for .338LM. There is no surviving a hit from these guns in Gunfighter. The best a player can hope for is to hit the ground and need to be rescued by a team mate. There is a much greater probability that if you are hit in the upper torso you're a dead man, and of course head shots are instant death.
I would also have an "accessory" for the snipers, available only for the Sniper scope which figures bullet drop and illuminates the proper place on the reticule.
What direction are you going with explosives and launchers? Am I going to be able to force entry with a breaching charge that stands in for my frag? How about actually blowing holes in the wall with Semtex? Speaking of door breaching, how about hinge-breaking muzzle attachments for shotties?
That mostly answers your second question I think. Explosives and launchers would either be nonexistent or I would need to build a system for them specifically. There will be no use for launchers so they aren't likely going to show up. I do like the idea of breaching so I would be open to include semtex that can only be attached to walls and doors, not thrown or left laying around. In fact if I were to include stuff like that it would probably be mission specific. Like you HAVE to blow open a door/wall just to get in. What I don't want to see is bots tossing perfectly timed and aimed frags, or "sticky" grenades - whoever dreamed that crap up. No using C4 to "troll snipers". Most of this stuff is complete loops that won't exist anyway. Snipers are annoying because players abuse the lack of realism to become overly effective with sniper rifles. The pissed off victims then grab C4, sneak up on the annoying sniper and detonate him. Or if you're me, you use rocket launchers to take care of snipers, which BTW is precisely how our armed forces deal with them. Anyway, if the sniper rifles are more useful when used properly, then we don't have so much annoyance and probably have less trolling to begin with. This game isn't going to be for people who think it's funny to get knife kills, or kill other players in "creative" ways, or simply abuse holes in the game design in order to win. It's all about the fight and teamwork, since it would be a two player game. Anyway, sorry for the long answer but there it is.
I would also build maps specifically for the use of snipers and like I've said before, reward players for using them correctly. Give them good opportunities, make the guns very effective when used correctly, just make it fun and rewarding. I think it would also be pretty cool if the snipers were the only way to find enemies without seeing them yourself. Like maybe they could spot them and their position would then appear on the other player's map.