being a machinist, i have seen hundreds [if not thousands] of mis-drilled holes in my lifetime.
this is with all types and thicknesses of materials.
i am not afraid of drilling any material. however, the proper machine must be used, as well as the proper drill [bit] for the job, plus having the work piece properly clamped and at 90 degrees from the drill spindle.
proper feeds and speeds [whether automatic or hand control] must be used so as to not work harden the item. this can be caused by too fast of a speed and too fast of a feed, or the inverse.
the best practice is to drill the hole[s] approximately .010-.020 [.015 preferred] undersized, then use a reamer of the size you want that fits the bolts.
however, the bolt holes need to be a little oversize to properly fit the intended bolt being used, and that oversize will vary depending on the bolt size.
for example, if your bolt is .005-.007 undersize, a 1/2" [.500 diameter] bolt measuring .493-.497 [which is common for that size bolt, fine or course thread alike] the "best" hole size for assembly purposes, will be .500, or 1/2", to an oversize up to .530" diameter. [approximately 17/32" which is .5312"]
as most hobbyist equipment have more runout than precision machines, it is not uncommon for the drill to cut the hole .005-.010 [or more] oversize, as well as egg-shape the hole. reamers will make the hole round again, thus the recommended drilling the hole undersize, then finishing with the reamer.
you must also deburr or chamfer the hole[s] when done to eliminate all burrs from the drilling/reaming process, and prevent stress risers from possibly occurring.
just my experience from drilling [possibly] millions of holes in my 45+ year machinist career in all types of materials.
your results will more than likely vary............