may sound a bit stupid but I will explain why I ask this.

Let's say you have combatant A, a granny with a handbag of Khorne (4W10+4, Tearing) and WS 20 Combatant B a crazy space marine with an absolute disgust for melee weapons, with BS 85 and WS of 10 with a Autocannon.

Battle starts, B wins Initiative, laughs and says: Ladies first

Granny Charges the Space Marine and starts hitting him with the bag o'apples. After that the space marine is SOL, cause he can't do anything. Maybe he can disengage, Granny charges him again. Over the long haul, granny will roll enough Righteous Furies for the Space Marine to die.

Soooo...

One tactic for the space-marine would be:

Maneuver (Move Action)the granny 1 Meter and shoot her in the face (Attack Action)

But for him to pull that of, he has to roll better then granny, and that doesn't look to good for him from a statistical point of view.

One tactic would be, just move, and shoot and hope granny misses her free attack

Another tactic would be:

Knockdown (Attack Action), and then move (Move Action) and eat a free action melee hit from granny (from the ground)

Next turn (unless granny has leap-up, then the space marine is SOL again) granny hast to stand up and move to him, can't charge and can't attack. She just moved. Now that's the situation my question is all about:

In his next turn, can the Space Marine shoot granny full-auto with his autocannon at point blank, or is he considered in melee again?

One point in the Rulebooks declares, that you can roll with WS for a hit AFTER you entered melee combat, and not that a WS constitutes entering Melee Combat.

The guardsman in my group regularly uses a shotgun in close combat, however I impose a number of penalties.

1: he is at -20WS for using an unsuitable weapon.

2: if the shot misses then it carries on it's intended path and will hit the first thing it comes to. (logical)

3: heavy weapons con not be used in combat apart from to club someone to death.

No one else in the group he tried this tactic for fear of hitting another team member but the guardsman doesn't seem to care about the rest of them.

no spacemarine stays in melee and uses the butt of his bolter as a improvised weapon and cracks granny's skull

bayonets are awsome as well

oh but to the question of when are you in melee i say when ever some one is attacking you with a melee attack,

normally this would require combatants to be adjacent but im surre reach wapons or large xenos could attack things with melee at a few meters range

if the huge xenos runs up to me with the INTENTION of hitting me, but he is out of actions, does he still count as being in melee with me?

(that's the basic question lol)

can you hit him with out moveing? then id say yes hes in melee,

and that was a poor tactical choice on part of the gm, but a classic warhammer failed charge moment

I'd say that a WS check of some kind has to be made before anyone can be considered to be engaged in melee combat.

In the example of the granny, when she gets up and moves to the marine with the intent of making a WS check against him, he would not be considered to be in melee combat with her until that WS check is made.

Taking turns in combat is an abstraction of events used to make running combat in the game a bit easer while, in the reality of the game world, the combatants aren't patently waiting around for their turn to come up -everything is pretty much happening at once. So, narratively speaking, when the SM is moving back after knocking the granny down (on his turn) she's getting back up (on her turn). When she's moving towards him (on the last half of her turn), he can open fire on her (on his turn after her turn has ended) with close / point blank range benefits depending on distance moved with possible negatives due to trying to hit a running target. When the granny makes a WS check, then it can be assumed that she's finally made it up to him again even if, according to the turns she made it up to him at the end of her last turn.

This is just the way I handle things. If a WS check is made, you're engaged. If not, then you're just in PB range ;-)