I bought a brand new one of these last week from the countryman of Derby and straight away I noticed a fault, I have been back to the shop but they are worse than useless ( especially the Poe faced bitch who works there )

The problem is that I put a new co2 canister in and it will fire once ok, but on repeated shots the power drops rapidly and by the 4th shot the gun is just clicking and is not producing enough gas to fire a pellet. However if you then wait a few seconds you can then fire a couple of shots, and again you have to wait a few seconds.
They tried to tell me I was using the wrong pellets!! But I am using the same pellets in my other 1911 (dark ops) and my cp99 with no issues. I have tried bisley practice, rws hobby and also Geco, all flat head.
Basically the shop is run by idiots with no customer service skills at all and are not prepared to exchange it or do a refund.

Any help or advice is much appreciated

Ps. The co2 is not leaking around its seal