Not wanting to use a good 4.50 mm drill bit, I took a piece of hardened rod and ground a groove in either side and welded it to a handle made from a cut-off barrel section.
The same type of tool can be fabricated for any deep channel. I have one for the FAL bolt extractor spring and extractor plunger, the FAL locking lever retaining screw channel, etc.
I later cut a clearance slot in the base for Romanian AKs using the front pistol grip lower handguard.
A pair of channel-lock pliers has worked very well. I ground the teeth to match the grooves in the FAL rear handguard support. It also works on the gas regulator, as does the bottle-opener on my pocket knife.