Detailed info about BF4 weapon statistical numbers can be found at this site - http://symthic.com/

Weapon comparison tools for all the weapons with all combos of attachments can be looked at and compared.

These 2 threads below offer some detailed models and discussions that two of the guys did to calculate the best combo for each weapon. Interesting read and these guys really dig into the underlying numbers. Helps you appreciate what goes on after you fire 1 bullet to cause you to hit or miss.

I often read thru the forums as they have a lot of questions or info about the game, things like what is best attachment for weapon xyz? I read just to see what others have to say.

http://forum.symthic.com/battlefield-4-technical-discussion/5867-brute-force-approach-to-bf4-gun-balance-optimal-attachments-burst-sizes-and-aim-targets/

http://forum.symthic.com/battlefield-4-technical-discussion/6012-optimal-weapon-attachments-for-average-gameplay-a-statistical-approach/

Below is the 2nd thread above's summary -

"General:

Muzzle brake configurations are the least accurate in terms of average horizontal recoil + spread followed by Compensator configurations, followed by No Barrel configurations

ADS – Standing:

Heavy Barrel configurations are statisically the most accurate configurations.
Compensator configurations have more spread than no Barrel configurations for the average shooting scenario. HOWEVER the maximum recoil + spread is actually slightly less (cannot be seen at images). Reason: The stronger recoils you have the more beneficial the Compensator gets in terms of reduced (absolute) horizontal recoil. Meaning that the inner shots are less accurate and outer shots are more accurate. Looking at the OUTER shots only, Compensator configurations are slightly more accurate than no Barrel configurations.
Potato/Stubby grip configurations will become significantly more accurate after the 10th or 11th shot due to the lower max spread.

ADS – Moving:

Ergo/Vertical grip configurations are significantly more accurate than no Grip configurations for the first 10 or 11 shots as well as significantly more accurate than Potato/Stubby grip configurations for the first 5 or 6 shots.
Potato/Stubby grip configurations will become significantly more accurate than Ergo/Vertical grip configurations after the 5th or 6th shot.



CONCLUSION:

Use Heavy Barrel if you dont mind the addtional vertical recoil.
Use Muzzel Brake if Angled/Folding grip is not enough to reduce the vertical recoil.
Use Compensator only if your weapon has high horizontal recoil (e.g. LMGs).
Use Angled/Folding grip if you prefer shooting small bursts.
Use Stubby/Potato grip if you prefer shooting longer shots.
Use Ergo/Vertical grip if you prefer shooting small bursts while moving.


Keep in mind that this is a statistical/analytical approach. Due to minor assumptions as well as approximations these results can never be taken 100% accurate or realistic. However the high similarity to 3VerstsNorth's results with the bruteforce approach shows that the statistical approach is absolutely a viable one and does provide accurate results that are within an acceptable margin of error. Please note that even thou the charts may give you a pretty good idea of weapon attachments and their influence on horizontal spread, this work does NOT provide any absolute numbers to rate weapon attachments!"