Original Choke Sizes?
 

How do you tell the original choke sizes on a Parker? I have a 1913 Parker Trojan 16 ga. and was curious if the chokes were ever altered. Just curious. They were listed as Improved Cyl. and Mod when I purchased the gun. Is it listed on the barrels somewhere?
Thanks,
Trey

A simple plug gage, such as the one from Galazan, may have been used to measure the chokes. A comparison of the actual bore diameter and choke diameter is the true method of ascertaining chokes. Performing a shot pattern test would be another way, I suppose.

Those plug gauges are worthless when it comes to measuring old Parker chokes.

Are there any markings on the barrels that would indicate how they were originally choked from the factory?

No markings on the barrels. A Research Letter may tell you what load and pellet count was when the gun was originally ordered.

Trojans were standard full and full unless they were the rare special order. Almost all were stock hardware store guns. A 16 ga Parker full choke is about .028.

To add to what Bruce posted, the bore diameter is usually the nominal 16 gauge reading of .665 plus or minus. If the factory letter shows full and full, the muzzle diameter should be very approximately .635.