I've restored a few canoes that used rail caps, and salvaged the copper nails that were used to secure them from the old parts that remained. These nails were held in very tightly. But I immediately found out that thin copper nails are extremely soft and bend very easily - there's no way they could be driven into wood without pre-drilling their hole. This pre-drilling took a lot of time, and I had to get the drill size just right otherwise the nails had no holding power. So I'm wondering how they did it in 'the old days' - I just can't see them spending all the time needed for fussy pre-drilling to get the needed holding power, nor can I imagine them taking the time to carefully hammer the nail so that it didn't bend. I'm sure we've all seen canoes where seat bolts often have to be pounded out of their holes - that the drilled hole has shrunk so much that it essentially turned into a tapped hole. So could it be they were counting on the same thing happening with the copper nails in rail caps? If they knew the steamed wood was going to shrink then the pre-drilled hole could be sized to have little holding power so that the nail essentially dropped into its hole with little to no hammering needed. Then when the wood cooled down the nails were tight in the holes. Am I wrong?