Stem bolt size question

[in4]

Anyone know what size bolt this is? It’s on my Deda stem and it’s  ’rounded off’ probably because I used the wrong size hex/allen key. I think it’s an M5. I’m not sure what the correct description is for the top of the bolt. Tapered crown perhaps?
TIA

[UKTony]

The bolts on my Deda Zero stem are M5 by 16mm. AK is 4mm. I think the bolt heads, albeit tapered,  would be classed as socket head. Spare matching bolts for various Deda stems are available eg from Condor Cycles.

[Danneaux]

Ian, a time-honored way to remove rounded socket screws is to pound in the next larger size Torx bit. The damaged screw usually twist out easily with this method.

Best, Dan.

[mickeg]

Bolt thread size or wrench size?

Usually, but not always the stem bolts that tighten onto the steerer tube are a 5mm wrench size, thread size 6mm.  But there may be exceptions out there.

[mickeg]

Ian, a time-honored way to remove rounded socket screws is to pound in the next larger size Torx bit. The damaged screw usually twist out easily with this method.

Best, Dan.

I have never heard of that.  That is BRILLIANT.