I should have mentioned that this same problem was discussed in a thread almost a couple of years back, and various options were put forward then, but none very convincing. https://www.airgunbbs.com/showthread...ighlight=Eagle
The most popular suggestion was that it was muzzle loaded. However, the gun was advertised as using conical as well as BB pellets, and would have needed a ramrod, but no such thing is mentioned in any of the adverts.
Guy, It certainly is not a repeater. If the end cap slid out, then somehow the means by which it is attached to the barrel would have to avoid the cross screw in the process. The same cross screw causes a problem for any sort of loading into the barrel.
(Incidentally the Stinger appears to have been made by Webley according to literature, and the gun itself is marked 'Made in England'. This does not exclude the possibility of course that Webley bought in some or all of the components and assembled it themselves.)