Thanks every body for your replies.
My rifle is a single shot without a safety.
I had a look at that website and most of it appears to be about how unsafe Remington triggers can be in regards to the safety, the trigger on this rifle looks to be untouched with factory sealant on the screws.
The trigger is very good if only it would cock each and every time.
Just strange it will cock at home every time but on the range with a live round it occasionally will not.
I don't have access to compressed air at home but will that matter if I give it a good swamp out with lighter fuel ?
Regards, Roly