Well, about a quarter century ago, I installed a salvage-yard Fintail Kuhlmeister AC unit in my '61 Ponton 180. Back then R12 was cheap and unregulated, and many add-on AC systems used barbed fittings with clamp-on hoses, but my salvage-yard compressor only came with a high-pressure fitting attached to a short chunk of factory crimp-on hose. Not having the correct barb fitting, I cut off the hose and collar, then carefully ground some shallow grooves in the fitting to give the new clamp-on hose something to 'bite' onto.
First warm day that AC was really cranking as I pulled away from a traffic light. Then there was a loud bang, as if someone had fired a shotgun under my hood, and the front of my car was enveloped in a large white cloud. I held my breath as some of the cloud forced it's way through various openings in my firewall into my front seat area.
Then I installed the correct fitting!

Happy Motoring, Mark

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DrDKW