Doesn't sound like the "sweet sixteen". Rather a regular A-5. I have one that belonged to my Grandfather; no money could buy it, but I don't shoot it because it has a "suicide safety" inside the trigger guard I don't like.
The older ones had 2 9/16 chambers and won't eject a 2 3/4 shell. Most of those have been 'converted' by extending the chamber and opening the ejector port. What to shoot in it is problematic. The spring and friction rings were adjustable for "high and low brass" shells which doesn't mean anything anymore. Yours seems to be a newer one with 2 3/4 chambers (at least that's what the barrel is) with the 16/70 marking.
You have to experiment. High enough pressure to eject is necessary, but too much will split the fore-end wood. You'll have to get used to the double shuffle ejection business too...Geo
