28 gauge Parker choke boring/testing

[mobirdhunter]

I'm reading about Parker choke boring as I gear up to measure/re-measure barrels, an ongoing Summer project of mine. In my reading I see that Ed Muderlak claims that all .410s and "some" 28s were targeted to measure chokes at 30 yards, rather than 40. I've not found any supporting information in TPS yet, but our home page FAQ section says that it's "possible."

I only have one Parker 28, a DHE grade, and the research letter states it was choked full and full (no pellet count). My initial (and quick) choke measuring back when I first purchased the gun revealed chokes a bit more open than the typical choke chart (again, the one posted on our home page FAQ link) suggests for a 28. However, if Parker did indeed target/pattern at 30 yards, wouldn't the constriction be less (compared to the chart) than if they targeted at 40 yards?

(I've not patterned my 28, and have shot it using spreader loads on the several occasions I've used it, so beyond a not-so-careful measuring, I don't know much beyond the fact that it kills quail if I point it well.)

**I'm curious if those of you who have original chokes in your 28s, and have a research letter for them, have measured those chokes and compared them with the typical choke constriction charts. If so, what are your findings?**