Just for the record, I use Newey snaps on my replica builds.
Before I scored the Newey snaps I used to use either Prym or Capica snaps. Both are very close in size to the original snaps. I believe the official name for this type of snap is 'S' spring fastener. There are many different brands available on ebay so no excuses not to use the correct type of snaps. And as you say, Germain, these are only good enough to be used in the same places as on the original armour. They are no good at holding armour together.