I have not had any problems shooting with additional oxygen. I have completed calibration using propane and mapp, but have not had enough shooting time to test with oxygen.
With plain fuel air mix I have achieved about 700 joules muzzle energy (only a 5' bsrrel, so chamber/barrel ratio is high), but some testing with an 8-foot barrel extension showed promising results).
I've cooked rounds with added oxygen (about 1/20th pressure relative to fuel) which I calculated would increase O2 content in chamber to about 22%. I fired about 20 rounds using remote trigger (2 boards and a string, pull string, board drops on igniter). I did not have the Chrony that day, but I noted a sharper rapport and a significant increase in muzzle flash.
Due to my current residence, I have nowhere to safely fire this unit (at least with this barrel and golf balls) so any further testing is off.
![😒](//twemoji.maxcdn.com/2/svg/1f612.svg)
Sadly golf balls are the least safe ammo due to the infinitely variable angles of return. And with over 800 yards range, I ain't taking that chance here.