Choke Variances...
 

So, I picked up a choke mearuring tool.....

Checking several of my guns, noticed the following.

1926 Parker Trojan, IM/F.
1927 Ithaca NID marked M/F is exact to the gauge as M/F.
1947 Model 12 marked F is exact to the gauge.
1926 AH Fox 16ga , per the gauge, it's IM/XF
1940 LC Smith 16ga IM/XF.
1947 Lefever Nitro marked F/F is F/F.

So, were chokes a bit tighter than todays in the 20's for Fox and Parker?
Or, is the R barrel of the Trojan likely F originally, then someone had it changed to IM? That doesn't make much sense, if you were opening it, why not go to M or IC?

Also, I have some removeable choke tubes from newer guns, that the gauge is way off on per how the chokes are marked.... Original Browing Invectors are true to gauge, but the Invector Plus, the F, shows as M, and the M, the gauge completely slides through it.

I read a review on this gauge where one guy swore it was off, because he had guns that he thought were full or Mod, that showed as Cyl, but the gauge is dead on for my Ithaca, and Winchester vintage guns..... It was all I could do to reply back to the guy that his guns were maybe not what he thought they were.... :D

Mostly curious about the Parker, as I thought all Trojans were F/F or M/F, but my right barrel is definitely IM on this gauge.

According to the "Flying Ducks" catalog, circa 1913, chokes on a 12 gauge Trojan with 28 in. barrels were mod and full. 30 in. barrels were full and full. 16 and 20 gauge were both mod and full.

What kind of tool did you get? If it's one that only goes into the end of the barrel it can and often is way off.You need a dial type that goes a foot or more into the barrel so you can measure the bore relative to the choke.

Just one of those simple tools, like galazan sells....

My gun is a 1926 gun, with 30" barrels

If you are using a plug in gauge similar to the Galazan model you are not getting a true reading of what the points of constriction are relative to the actual bore diameter of the barrel. Those types of gauges are machined and marked relative to the supposed nominal bore diameter such as 12 ga. = .729. My Galazan gauge measures .690 for the full choke ring. Subtracting the constriction from the (supposed) bore would then yield .039 or full. Many early guns were bored different from nominal so what you see from a plug in gauge can be very misleading. You need a bore micrometer similar to a Skeets Bore Gauge to determine actual bore diameter then points of constriction and do the subtraction correctly.
The Invector Plus Browning guns are back bored so the chokes are relevant to their actual bore diameter which make them seem open using a plug in gauge. Hope this helps, Joe.

The only way to measure choke performance (the only thing that matters) is to pattern the gun by shooting into a 30" circle at 40 yards and determining the % of pellets in the load inside that circle. Every other measure merely tells you the constriction, some tools do it roughly and others do it precisely in thousands of inches. I have mentioned before I have a Remington 1900 KE with .014 and .024 constriction and it shoots 72% and 86% or full and super full yet the measurements suggest IC and Mod. I have a barrel on a Lefever 10ga with .018 constriction and shoots 85%. With .018 in 10ga I expected a light modified possibly IC, not super full. Conversely I have a 20ga Trojan with .005 in one barrel, I expected IC, it shot 33%. The other barrel has .012 and it shot 56% which is what I expected.

Remember that there is a significant difference between shells made at the time the gun was made and our current offerings, even RST shells. I have found a drop in choke gauge to be *almost* useless. As already posted, constriction is a strong clue, but the pattern board is best indicator. I have found that I can “change” the pattern by a choke designation by changing loads (even without spreader inserts). Always best to pattern the gun with the shells you plan to shoot.

And when these chokes were originally cut, plastic shot cups and shot collars had not yet been invented and some resulting shot deformation was not uncommon. This often resulted in a slightly more open pattern than we might see today using the same load and shot size but with the advantage of cushioned plastic shot cups which protect he shot from a similar deformation... often resulting in tighter, more uniform patterns.





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If you are just using a drop in gauge, then you do not know what the chokes are. Period.

Those are only accurate if the bore measurement is nominal for the given gauge (ie: .729” for 12g).