The weapon destroyed result was on the Heavy Flamer it seems, you don't actually lose the arm. To lose the extra attack you'd need to have had the CCW destroyed.

Check on Page 84 of the BRB.

Think about it though Magpie.. if you could destroy what IS specified as a built-in weapon separately from the arm it is attached to, then the reverse would be true, and you could somehow destroy the Dreadnought arm without losing the Heavy Flamer, which doesnt make sense.

I'm relieved we're in for a re-roll of course, but if I lose legitimately, then well done Angel of Blood (and if I lose in the same way, then thats what I get for being a nooblet and forgetting about the craptastic Morale of Guardsmen)

It's not about "sense" it's about what is in the rules. You can't destroy the arm.
The result on the damage table is "weapon destroyed" not "arm destroyed"

If you want to talk practicalities then the models clearly have the flamer hanging off the bottom of the arm, very easy to shoot it off and leave the talons operational.

Under "Wargear" for the Death Company Dreadnought, the Bloodfist with Built-In Weapon is listed as One Entry, not two separate ones. Therefore it is reasonable to assume that they are treated as One Weapon

Yet you can change the fists to talons without losing the "built-ins"

What ever the semantics of it, the Dreadnaught has 4 weapons. Two fists/talons, a H Flamer and a Melta.

Any Weapon destroyed result needs to randomly destroy 1 of these, leaving the others operational.

If there were four separate weapons for the purposes of weapons destroyed, it would have four separate weapons listed under "Wargear". There are not, so it does not.

Just so I'm not holding out false hope here Spanner, what's your official ruling on this?

If your going to bring the model into it, then I'll point out that the Built-In Weapon, whatever it may be, is always attached to the underside of the Fist/Talon. Anything that blows off the Fist/Talon would take the Built-In Weapon with it.

Not necessarily, it could be a simple as something breaking the promethium hose, however all that is irrelevant as we should be going off what the rules say.

Would it be possible to see my results laid out turn by turn. I'm surprised I dealt so little damage and took so much. Also if he overheated how did he do a wound?

I'm just trying to make sure everything got accounted for, like the leadership check at -2 for when he lost close combat.

Not sure but it might be rapid fire, one good shot and one that overheats ?