Often sand from refinishing remains in the firing pin channel. This is dangerous because it can wedge the firing pin in the forward position and cause slam fires.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.
Having the rifle in a secure stand helps with installing the trigger group. I use a defective magazine welded to a steel plate. You can make the stand as simple or as elegant as desired. Make sure the magazine is long enough to allow the rifle to rock far enough forward to remove it from the magazine. I failed to do so on this one so I had to add the second plank (a 24″ laminated shelf) to the base to get the necessary height.I later cut a clearance slot in the base for Romanian AKs using the front pistol grip lower handguard.
I got tired of breaking spanner wrenches from other companies that lacked sufficient harness for the intended purpose. The DSA, for example, would often fail on first use.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.