Here are two pictures:

Two magazines from M4A1 shot while walking sideways:

Two (or three?) magazines from M4A1 shot while standing still:

\

There should be some way to alter a gun's accuracy depending on the player's movement (standing, walking, sprinting). I would suggest:

A. Have 3 fields for accuracy:

Accuracy 2
//this is accuracy while standing still

WalkAccuracy 4
//this is accuracy while walking normally

RunAccuracy 6
//this is accuracy while sprinting/running (SprintAccuracy would work too, but it's longer :P)

If Walk or Run Accuracy are left blank, then they will be defaulted to whatever is set on Accuracy.

B. Have a hardcoded adjuster for accuracy. This could be coded into the mod itself, but it would mean less freedom for pack makers (what if I want to run and shoot accurately?).

Accuracy 2
//standing accuracy. If WalkAccuracy is hardcoded as Accuracy + 2, then WalkAccuracy would automatically be set to 4. (2 + 2 = 4)
If RunAccuracy is hardcoded as Accuracy+4, then RunAccuracy would automatically be set to 6. (2 + 4 = 6)

C. Implement a "compromise" (as a pro gun person, oh god I hate using this word) between A and B. Allow WalkAccuracy and RunAccuracy to be set by the user, but if they are left blank, then WalkAccuracy is set to Accuracy + 2 and RunAccuracy is set to Accuracy + 4. This allows total freedom for pack makers, while other (lazy :p) pack makers will still get the accuracy adjustments while moving.

I seem to make these suggestions pretty detailed...
maybe because of: "Could you explain this a little further? I don't quite understand how you want it."

also I still want scoped-in accuracy bonus :D

i bet you're reading this, godgodgodgo

Very detailed thank you :P this would be a great feature.

I aim to please. :)

Unless Flan forced you to sign an NDA, can you tell me how you're going to implement this feature (if you are)? I kind of want to prepare some of my packs.

I don't personally do any major changes to the mod, I just manage the issues and make/test small changes for future releases.

I would imagine it wouldn't be too difficult to implement option A with something like;
If player state =
sprinting then use SprintAccuracy
flying then use FlyAccuracy
etc. you get the idea.

The same could then be done to check if the player is scoped in to adjust that accuracy. I definitely think option A would be best as then higher accuracies could be set to light weapons than heavy weapons when sprinting etc.

Heh, FlyAccuracy. I'll just twiddle my thumbs and wait until one of you guys implement it (hopefully with some other neat features (sentries :p) ).

Summer's coming up, just hope that Flan isn't doing too much traveling or anything and has time for development ;)

I hope so. :)

so there are these states (I don't know if they are all available in MC's code):

Standing still
Sneaking while standing still
Walking
Sneaking while walking
Sprinting
Flying
Swimming
Riding a minecart (this sounds fun)
Riding a boat (this...not quite)
Falling/Jumping

Any others? Not all of those are really important. Some (or most) statuses can just be lumped in with others.

That seems to cover most of them however I think maybe only the main ones should be covered.

Definitely. Most of them don't really matter.