Lubing the ammo or chamber is a very dangerous practice.
Friction between the case and chamber wall is expected to slow rearward travel of the fired case. When you take the friction away, this increases the stress on the bolt, causing increased chamber pressures.
In the 1920's the practice of greasing cartridges was found to dangerously increase chamber pressures and was forbidden in the U.S. Army for that reason. Hatcher writes of experiments performed by Col. Townsend Whelen, citing the following recorded pressure readings using National Match .30-06 ammo: prior data for the ammo used in testing = 51,335 PSI; same ammo lightly lubricated with Vaseline averaged 59, 000 PSI; same ammo with bullet, case, & chamber lubricated = 71,154 PSI. :shock: The latter wrecked the pressure-testing device, which Hatcher says was stronger than an ordinary M1903 action.