I personally find it a little strange that you're not able to use Hand Flamers with the arm mount. Has anyone tried to house rule it, and if so, how has it worked out?

I've honestly never noticed that the forearm mount was limited to pistol weapons until recently so I've been permitting all manner of basic weapons to be arm mounted. Since arm mounted storm bolters are so prevalent amongst some uber elite marines I just never gave it a thought.

Thus I would see no problem with a hand flamer being arm mounted. IN fact in rites of battle there's a relic flamer that's forearm mounted.

I would allow it, the range will lesser the power in close combat vs hordes but it would be a marvelous backup weapon...

I'd allow hand flamers.

Tha said, the rule isn't clearly written. In background, arm-mounted basic weapons are generally for high level named characters (e.g. Marneus Calgar) and grey knights who get a pile of gear unique to them.

I'm the same, I can easily see a Hand Flamer on an arm mount. Basic weapons.....not a chance.

Same. I allowed it in our game