We used all sorts of extended leverage, heat, impact guns the works and they wouldn't budge. Shattered 3 allen drives before they got the wizzer! Never thought of drilling the heads off but they'd still be stuck in the brackets rendering them useless.After comparing the remnants of the deceased bracket, the bit where the bolts screw in on the replacement bracket is almost twice as thick.
Not so, you can get them out generaly with your fingers or a pair of grips, worst case grip them in a vice and unwind.
I find this the best method when an Allen socket/stud extractor has stripped itself out.
Drilling out allen bolts is very easy as you have a pilot for your drill already in place, I use a 10.5 for 10mm bolts (0.5mm bigger is the general rule)
