A bud gave me a paper copy of A test of Rifle, caliber.22, AR15; Rifle, Lightweight Military, Caliber .224 and Pertinent Ammunition
, Larry Moore, 3 Feb 1959 to examine. I can find the title of this document on the web, but not the text. I copied the data, to be found in the report , of the pressure and velocity of oiled and wet 224 rounds. You can find the velocity and pressure of the dry rounds in
TEST OF RIFLE, CALIBER .223, AR-15 Report No. DPS-96
Dates of Test: 21 September to 20 October 1960
So, here we have pressure and velocity data showing that cases dipped in oil (and water!) do not cause pressures to increase.