Accidentally unscrewed acetylene regulator without first bleeding pressure off hoses.

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New member here.  I'm a fairly experienced welder, though no formal training.  Own a mig and a Dialarc 250 AC/DC, but haven't owned a torch for years.Finally broke down and purchased a new Victor Journeyman Edge 2.0 plus set and a couple bottles.  The acetylene bottle seemed low to me.  It only reads 130psi at a temperature of 60F.  This is a brand new exchange bottle.  My other bottle of acetylene registers 200psi at the same temp.  It is not an a brand new exchange bottle.  Obviously, the "new" acetylene bottle is not full.My question is, is this a very common occurrence with gas distributors?Also, as the topic indicates, I was busy switching the acetylene regulator back and forth between tanks to compare readings, and forgot to bleed the lines of gas before unscrewing the regulator, once.  I realize this is a no no, but made that mistake.  So the gas line bled back through the regulator (i.e. forcing the gas to go through the regulator the wrong way).  The regulator still seems to function correctly, but is there a chance I screwed it up?
Reply:Doubtful it screwed up anything. So basically you just got a little pfft of gas? I don't back off regulators when changing cylinders, just close valve at tank and bleed it at torch thru that valve, if at all.
Reply:You really can't reliably tell how much acetylene is in a tank based on the high pressure gauge. A full tank can have have a huge pressure variance bases on temperature. https://www.esabna.com/euweb/oxy_han...589oxy3_18.htmMiller Multimatic 255
Reply:Unscrewing the regulator without bleeding won’t hurt a thing. The trapped gas just exits through the orifice and seat after the seat has opened to allow more pressure to enter the hose. It would be no different than leaving water trapped in your garden hose, turning the water main off and then opening the hose bib.
Reply:Thanks for all the replies.

Originally Posted by Louie1961

You really can't reliably tell how much  acetylene is in a tank based on the high pressure gauge. A full tank can  have have a huge pressure variance bases on temperature. https://www.esabna.com/euweb/oxy_han...589oxy3_18.htm