I've owned/shot/hunted with both a Beretta Companion (12ga, though), and 3-4 different AL-48's (standard & magnum models).
As for setting the friction ring:
If you look at the brass ring, it has a steel ring on the outside that holds it tight.
As this slides on the mag tube, it hits the spring.
The bevel ring on top of the spring can be flipped for light or heavy loads.
If the bevel is towards the brass ring, it's for heavy loads - as the ring is pushed back by the barrel, the beveled ring will compress it making is grip the mag tube more tightly.
Conversely, for light loads, if you flip the ring so the flat side is against the brass ring, it just slides and does not compress.
Last edited by PetahW; March 3, 2013 at 11:29 AM.