M40A3 = Very accurate, medium damage. With stopping power you can down almost anyone in a single shot and with it's accuracy it's much easier to score a hit to the center of the body. Very deadly.
M21 = Fairly accurate, low damage but also low recoil. With the low recoil you can fire follow-up shots without too much effort. A fun gun to play, just don't expect one hit kills and try to conserve ammo. Quite effective with an ACOG scope as an M14 alternative with less ammo and lower recoil.
R700 = The M40A3 is a much better weapon with stopping power, but the R700 has the ability to get one-shot-kills on the upper-chest and head without stopping power. It's less accurate than the M40A3 and has only a little more power. Not enough power to kill in one shot to most of the body without stopping power, and with stopping power added the M40A3 still has superior accuracy. This is a good sniper rifle if you want to dedicate the 2nd perk slot to something other than Stopping Power.
Dragonov = A very good gun. Basically a M21 with much more power and a little more recoil. You tend not to use as much ammo with a Dragonov as you do with the M21. The accuracy of the Dragonov isn't as good as the M40A3 but it's still very good.
Barrett = Very powerful and fairly accurate. Strangely enough you can actually use this weapon at close range. If you're moving around at close range and someone surprises you, begin firing like crazy and you'll probably kill him.
NOTE: In Hardcore mode the weapon balance changes considerably. In Hardcore mode all sniper rifles have the capacity to kill in a single shot, even without the stopping power perk. Since all rifles deal lethal damage, the traditionally weaker M21, with its good accuracy and low recoil becomes much more deadly than in regular games. Conversely, the more powerful guns tend to lose their usual power advantage over the traditionally weaker weapons.
this is what I think about these guns :
Barret = The Barrett .50 Cal's accuracy is seriously NOT bad if you get used to it. Its actually very good and my fav sniper rifle. If you hold the Steady button immediately as you aim down the sight, it automatically steadies 90% of the time, and with Iron Lungs, you have a steady aim for a long time. Also, since the Barrett is a one-hit kill without Stopping Power, this frees up Perk 2, which has a lot of amazing things.
R700 = I'm one of those you mentioned who loves the Remington 700. I find it as accurate as any rifle in the game, with better power than the M40 (which is unrealistic since both the M24 and M40 are in fact Remington 700's...but oh well).
Styles of Play:
True Sniping = Find a concealed position and take accurate shots at select targets, preferably from long range. Due to the killcam and the natural flow of battle, you may need to relocate every couple kills. It's probably a good idea to choose your shots as firing too many times in quick succession is a dead givaway of your location. I suggest using claymores to cover your blind spots while concentrating on your target.
Designated Marksman = Essentially a regular player who uses an accurate assault rifle or sniper rifle and prefers to fire fewer more-accurate shots from a longer range than more less-accurate shots at shorter ranges. The G3, M14 and M21 rifles are excellent DM rifles but others will do as well.
Snap-Shooting = The idea is to strafe like crazy, constantly ducking in and out of cover, and fire accurate, powerful shots as quickly as possible for the split-second that you're exposed to the enemy. An ACOG scope is definitely recommended for this style of play. There are five key elements to this style of play:
1. Movement - Don't stay exposed to enemy fire any longer than it takes to fire a shot, if you miss, don't worry, strafe back to cover and try again, don't linger and try to make the shot unless your absolutely positive you know what you're doing.
2. Cover - Cover is your friend, if you lose your cover, you're toast. If your moving through an area without cover, have a backup plan in case you come under fire such as quick-proning or sprinting.
3. Quick-scoping - Get used to scoping, aiming and firing almost instantaneously in one smooth motion. There's not enough time to zoom and aim carefully before firing. If you can practice this enough it'll almost become instinct. Eventually you may even be able to begin taking out close range targets with a sniper rifle. This is much easier with an ACOG scope than with a regular scope, but you lose your ability to sniper at longer ranges. ( And alot of people use quick-scoping skills in mw2 )
4. Power - Try to use a weapon that'll leave a mark if you hit your target. You need to make your shots count as you'll only have time enough for a single shot in-between ducking in and out of cover.
5. Unpredictability - Don't try to strafe into the same location too many times in succession. Mix it up, keep you opponent off balance and make him readjust his aim in order to hit you.
That's just another one of my tuts or Tips&Tricks.
"Holding anger is a poison. It eats you from inside. We think that hating is a weapon that attacks the person who harmed us. But hatred is a curved blade. And the harms we do, we do to ourselves."-Mitch Albom