Peasant Railgun

If I were the DM, I'd allow it.....but the players have to roll for each commoner sequentially to see if they can do their part. And the rolls get harder.

If they want to spend 3hrs making increasingly hard rolls as the pole speeds up, more power to 'em.

Yup. Each peasant after say the first 4 give me a DC check that gets harder to catch/pass the projectile down the line. If you need to be a 3rd level monk to potentially catch the missile, and not even rethrow the missile unless you get the damage to zero, this isn't getting up to any dangerous speed before hurting someone in the line. At least under my ad-hoc ruling.