How to compare guns in BF3

I cannot find a definitive source for this, but apparently:

• 40mm flechette rounds are unlocked after ten 40mm grenade launcher kills

• 40mm smoke rounds are unlocked after twenty 40mm grenade launcher kills

Why this can't be displayed in the battlelog in some form along with all the other zillions of weapons unlocks, I have no idea. But this is what people reported from the beta.

edit: confirmed, by me personally getting the unlocks. I presume the same rule applies to the Support class mortar, get 10 kills with mortar to unlock smoke mortar rounds.

It is my understanding that the last co-op mission "The Eleventh Hour" is the best on a "time spent vs co-op points earned" basis.

The Eleventh Hour

The attack has started. We’re confident this is the main attack referred to by El Zakir. Witnesses claim bomb like devices have been left in the metro and the Paris Stock Exchange. If Abdul Rahman is behind this attack, we expect it to be similar to the one that took place in London several years ago. You will be assisting the French police to locate and disarm the bombs and neutralize Rahman if the opportunity presents itself.

There are two things you can do on the final co-op mission to optimize points:

1. When you reach the bank with the police, don't advance up the steps. Apparently enemies respawn forever if you fail to advance up the steps, and people have reported mission scores of up to 200k here. However, I don't know if this is efficient on a time spent to points earned basis.

2. When you reach the bomb, intentionally fail to enter the correct code. Then repeat the mission. Apparently you can get between 3k-5k points in a little over a minute (say 1:20) with this method. That means you'd net around 180k co-op points in an hour.

There are a few co-op missions I'd definitely avoid as they take a long time to complete; the last mission feels like the shortest one to me.

Feel free to try it out and let us know how it goes!