Or you pull up the air release valve on the grease gun to let off the pressure.
I now use this gripper & it is brilliant. well worth £7.
https://www.ebay.co.uk/itm/Nipple-Gripper-Locks-On-Stays-On-Grease-Gun-G-Coupler-1-8-BSP-UK-STOCK/273778872326?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649


JohnV6
2022 CX Plus Four
2025 MG ZS EV aka Trigger