I think a lot of people are mixing up Accuracy and Bullet Speed. Think about it ; is the Barrett or DEs/Socom more accurate, or the MP5 or Aug is more accurate?
Let's take a look at the MP5 and Aug first, for a start. The MP5 has movementacc 1, bink -11. Aug has movementacc 2, bink -22, as well as a bug of having any shots after the first being angled slightly upwards. Would you say the MP5 or Aug is more accurate? MP5 is actually more accurate.
Then there's Barrett and DEs. Barrett has movementacc 7 and 100 bink. Even if you use the method to overcome movementacc, you'd actually still have a slight inaccuracy. DEs have absolutely no bink and movementacc 1. The DEs are actually more accurate, since the bullets always fly in the same curve no matter the circumstance.
Why do I say this? Accuracy is how precise the weapon is. Bullet speed is how fast the bullet travels and how much it curves. Why some people say that a gun to be accurate is because they might have mixed bullet speed and accuracy.
Bullet speed is just one of the factors that affects your own aim, not the accuracy/precision of the weapon, just as it is when you compare the Aug and AK, which are said to rival in accuracy. The AK may seem easier to aim because there is more time between each shot, despite having lower bullet speed. Similarly, people will find the Barrett easier to aim with compared to the DEs, because the bullet of the Barrett flies so straight and swiftly, while the DEs have a very awkward curve and travel quite slowly.
The same kind of thing applies when we try to determine whether a gun can be used for long range or not. DEs, despite having that low bullet speed, can be used for long range (though very hard) because of the accuracy and high damage per shot. The MP5 couldn't have been used for long range despite having very similar bullet speed to the DEs, because its damage per shot is simply too low and its accuracy is definitely not as good because of self-bink. Bullet speed is just one of the major factors to determine whether a gun can be used for long range or not.