OWD: Yes, a neat little roller secured with a threaded pin.
The picture in the Baker/Crudgington book shows the bar action version of the mechanism: similar but the other way up.
Although I agree that the spring is a nightmare, I think he designed this to get round a common problem with converting back-action locks to rebounding: lack of room.
As you can see it doesn't rely on the 'passive arm' of the spring reaching the tumbler like the normal Stanton rebounding lock mechanism. This lock beautifully illustrates the problem of the sear spring being in the way.
I suspect that this gun is a conversion from non-rebounding as the normal Stanton patent is perfectly suited for a back-action lock providing it is designed around it. However, as soon as the sear spring has been fitted in the usual non-rebounding position it often makes a normal conversion much more difficult, involving blanking off the sear spring pin hole and refitting it in a different place.
In fact, I think that one could use the general idea with a normal non-rebound spring, fitting a roller instead of a swivel and adding a suitable shaped extension to the tumbler with a cam shaped to suit.
I must try it some time soon!
Sorry if that offends anyone!
