Second Q - if a enemy moves to B4 can the Gun claim WA i.e. can emplacement be forfeited?Yes to the first question :
G5.1 : ... Except as stated otherwise, huts are treated as wooden Single Story Houses (unless Collapsed; 5.51).
G5.51 : A Collapsed hut is Concealment Terrain only for Infantry (and their possessed SW), Dummy stacks and Emplaced Guns.
Which implies that Emplaced Guns can exist in huts, even after they have collapsed.
I don't understand the second question : do you mean "with an enemy unit in the same hex"?
In that case it loses WA - but the wall still protects it from incoming fire from non adjacent units.
If an enemy moves there, it too late to claim WA and stop the enemy from claiming it (might be an exception if the Gun is still hidden, NRBH). Otherwise a Gun+crew can claim WA - but any Emplacement would later be lost if they voluntarily forfeit it.Second Q - if a enemy moves to B4 can the Gun claim WA i.e. can emplacement be forfeited?
I think it is - but WA (Wall TEM) is not in-hex TEM.So claiming emplacement in lieu of in hex TEM etc is for the duration of the phase not per shot/basis?
However, if that +3 building was surrounded by a wall over which the gun had WA and it claimed use of the building TEM ILO of emplacement/wall TEM the gun would lose WA. As to when a unit can claim either an in-hex TEM or its emplaced/WA status, it is on an single attack basis. [EX: An emplaced gun in a stone building hex with a wall around the the hex (or any portion of it) has declared, or been given per previous HIP status, WA against a shot at it. The firing unit has retained fire and wishes to fire again. The WA gun may now claim to still be using the WA/emplacement or decline and opt instead to use the building TEM. However in this instance it has forfeited WA (but not emplacement-for whatever that may be worth)]. Once WA has been declined it may not regain WA until one of the times and noted circumstances of B9.32.I think it is - but WA (Wall TEM) is not in-hex TEM.
If you have an Emplaced Gun in a stone building I think they can claim either +2 or +3 TEM per attack.
Emplacement would be lost, since Emplacement is lost if a Gun's manning Infantry voluntary forfeits WA, per C11.3.However in this instance it has forfeited WA (but not emplacement-for whatever that may be worth)].
Right.Emplacement would be lost, since Emplacement is lost if a Gun's manning Infantry voluntary forfeits WA, per C11.3.
An AFV can't claim WA if there's an in-hex TEM.This switching of WA and in-hex TEM on a shot-by-shot basis does work for AFVs in a building, though.
Of course you are right. What you describe is actually what I had in mind. Not WA but selection between HD and in-hex TEM.An AFV can't claim WA if there's an in-hex TEM.
B9.32:
"A unit may claim WA over a same level wall/hedge hexside if it is an armed, unbroken ground level unit which is not: a vehicle eligible to receive in-hex TEM of ≥ 1 [EXC: Height Advantage (10.31)/Cactus Patch (14.7)/Olive Grove (14.8)]..."
Vs non-adjacent firers I do think an AFV in a building being fired across a wall hexside can choose to building TEM of Hull Down from the wall.