Three Jaw Chuck--Tighten All Three Sockets?

[The Metal Butcher]

No reason for getting that dramatic now - take a deep breath - rubber would probably flex inches with those kinda loads while hardened metal tenths of a thousand's of one...

Hardened steel has the same elasticity as unhardened steel. It is a material constant.

[A.K. Boomer]

Hardened steel has the same elasticity as unhardened steel. It is a material constant.

Technically not so - 5% is after all 5%

also, keep in mind about the high load contact points and conformation there of, hardened resists deformation so it's a double wammy worth mentioning when picking apart details...

https://www.machinemfg.com/elastic-modulus-stiffness-strength-and-hardness/?utm_content=expand_article