surface and a pair of diametrically opposed longitudinal slots 9 extending from the front end 8 to the rear end 7 and wherein the spring tube 6 is slidably disposed within an opening 10 in the slide 5 best shown in fig4 and 5 an inner spring 11 resides within the spring tube 6 wherein the inner spring 11 includes a first spring constant in a more preferred embodiment the inner spring 11 is the main recoil spring although such arrangement is not necessarily required by the present invention an outer spring 12 resides around the outer surface of the spring tube 6 wherein the outer spring 12 includes a second spring constant as mentioned above the inner spring 11 may often be the main recoil spring if that is the case then the second spring constant of the outer spring 12 would be less than the first spring constant of the inner spring 11 in other words the outer spring 12 would be much lighter or easier to compress than the inner spring 11 the outer spring 12 includes an annular cap 13 connected to the front end of the outer spring 12 a locking device 14 is disposed within the front end of the inner spring 11 best shown in fig2 and 4 and includes opposing tabs 15 slidably engaged within the slots 9 of the.