I reckon we should definitely have more barrel attachments. i don't mean the barrel itself, I think we have enough of them. I mean things like muzzle breaks, compensators, flash hiders etc. Since in RL, the muzzle attachments help direct the recoil in another direction.
For instance, the legendary Barrett M82 has a killer muzzle brake seen here:
I'm not saying put this weapon in BFP4F but have different attachments similar to this (or at least similar to its use since the one on this Barrett helps divert the gases towards the rear of the weapon, pushing the rifle a little further forward although the force of the round will still generate a lot of recoil, not to mention the gases that are diverted up and into the gas rod to restart the cycle since the M82 is semi-auto.
Oh and as someone has already said, I really hope that the silencers are realistic and not those similar to those in Hollywood. And also, I would like very much to have variable sights/adjustable scopes. For sights, it means more than one per attachment for scopes, it would be one similar to the Enhanced Scope M95 which I seriously regret not buying.
Also, since the BFP4F maps aren't the darkest of environments, I don't think flashlights will be a necessity (rather just to look kinda cool) but laser pointers might help a little more.
One more thing that I've wanted for a very, very long time is selective fire. I know this might not be the place to suggest this but it could be an attachment. Somehow... I've just found it hard to potshot long distance targets using ARs, LMGs an SMGs.
Oh and Diwan, you've got your cookies. Now let's see some skin(s)