Hey friend, Ya cannot order the endcap from any site. You have to call in the order. It is just a plastic cap,and cheap. I may end up making one outta a copper cap as co airgunner did or alluminum for a nicer apearance. As CDT posted,the spring block pin cannot no how no way come out on it's own,but Yeah aesthetics are ugly without a cap of somekind. However the stocks,trigger guards (which you will also need) can be ordered at Gamo USA.com. Gene told me that the linkage roller also needs changed to complete this mod properly.I dont know that Gamo sells them by phone, but Gene said he could make me one on his lathe. I am gonna get my 440 stock customized before installing,cause this is naturally gonna be a very common mod among Synthetic Gamo owner's. Oh! almost forgot,the endcap item# is 15050,but they will know what your talking bout if ya forget #.AKJC1977