By strange coincidence I have just been house ruling a simple snapshot-like action point system, but closely based on Mongoose combat. My complete rules are a bit more detailed than below, but it's actually a very simple system that doesn't require very much book keeping.
The system seems to promote weapon skill, reflexes and above all tactics. I appreciate it isn't to everyones taste, but I prefer it to vanilla Mongoose combat. Please don't be too mean to it!
Here's a very rough summary:
Since we know from the CRB that everybody can perform one significant and one minor action in six seconds it breaks down nicely to 6 action points, modify that by dex DM to give 3 to 9 action points. No initiative, turns are simultaneous (as far as possible) all starting at the first action point then the second and so on, but a tactics roll(int) is made by all combatants at the start of combat to determine the sequence that orders must be declared, lowest declaring first.
No hastening, no delay, no free actions, no full autofire (just single or burst fire). Action points and tactics are dynamic. Leadership rolls add effect to one persons dynamic tactics for the next combat round.
A simple conversion for any action; consider how long it actually takes the average person- one second is equivalent to one action point. A minor action such as aim is 2 action points. A normal attack (significant action) is 4 action points. For faster firing, 3 types of 'snapshot' each being one action point faster than the last and suffering an extra -1DM (so a 3 action point snapshot would be -1 DM, a 2 AP snapshot would be -2DM etc).
Recoil and heft do not effect dynamic tactics, but require a pause in attack of one action point otherwise you suffer your recoil/heft as a negative dm on any subsequent attacks without time to recover your weapon. A reaction (dodge/parry) is not free but requires an action point, if you win your tactics roll you will be able to anticipate when to parry/dodge. Actions (taking more than a combat round) may be carried over.