Congratulations on the Trojan 16. The quail gun I carry most of the time is a VH 16.
The doulblegunshop.com has a section with much shotgun info- shot size, gauge diameter, choke information etc...
http://www.doublegunshop.com/info.htm
That is where I copied this table:
Shotgun Chokes (*typical values) for a 12 bore gun
Points** Inches American European % of Pattern in 30" circle @ 40 yards***
0 .000 Cylinder S 40%
5 .005 Skeet VZ 45%
10 .010 Improved Cylinder 1/4 50%
15 .015 Skeet #2 - 55%
20 .020 Modified 1/2 60%
30 .030 Improved Modified 3/4 65%
35 .035 Full 1/1 70%
40 .040 Extra-Full - 75%
I would use the same set up for a 16 gauge shooting an ounce of lead.
Best,
Mike