hi charleym3,, take the plug out,,,there should be a screw on the end of the mag tube on the muzzle end,,,put your thumb on the end of the mag tube and hold it in,,, take the screw out,,,hold on to that plug or it will get launched,,,,relieve the spring and the plug should come out with the spring,,,take it out and reinstall the spring,,cap and screw,,no need to cut the spring,,
this will only apply to the cowboy model
don't know if you will get 14 in the tube or not but it will be more than 10
hope this helps
ocharry