Good Day, I'm new to airgunning and I've chosen to use the Crosman 2240 in .22 cal. I've started to construct a 2240 out of Stainless Steel parts. I'm having trouble fitting the gas port to my barrel which is a standard Crosman 10" unit. the hole in the barrel seems to be too small. What should I do to correct the fitment of the gas port to the barrel?