against a perpendicular plane 111a that is distal to the conical region 111 of the shaft 110 until no further movement of shaft 110 is possible at this point spring loaded wedge 51 on annulus 50 slips on gear 70 as during locking this slippage is audible to the user of the locking device 30 in the form of a clicking noise here the clicking indicates to the user that the unlocking procedure is complete accordingly the locking device 30 is free to be pulled out of the firearm chamber and barrel 41 by the user again this arrangement protects against damage to the device 30 and the firearm 40 during operation further fig3 and 4 show details of the cams 150 160 cams 150 160 include two pieces one piece is a contact pad which abuts the inner surface of the chamber not shown or the inner surface of the barrel 43 the contact pads are designed to be replaceable the other piece is an intermediate piece between a pivot point on the cylinder 140 and the contact pad specifically seen in fig3 cam 150 includes a contact pad 151 that is fixed upon its respective intermediate piece 152 in fig4 cam 160 is shown to be articulated in construction a contact pad 162 of cam 160 is pivotally mounted including spring 163 by a small pin 165 upon its respective intermediate piece 164 which itself is pivotally mounted and pinned to the cylinder 140 alternatively a hinge not shown may be employed as a pivoting means in contrast to cam 150 the contact pad 162 of cam 160 conforms flatly to the inner barrel surface 43 or inner chamber surface not shown the surface of this contact pad 162.