I recall seeing somewhere what the differnt Ithaca choke designations mean; i.e. 2, 4 etc. but cannot find it again.
Can anyone point me to where I might find the "decoder ring"?
4=Full
3=IM
2=M
1=IC
0=C
Sorry-don't have the actual dimensions but this is what Hunter Arms used. The 16g bore was .650 into the early 30s however.
http://www.lcsmith.org/faq/chokedim.html
On a few early Ithacas when, they first started marking choke,
they marked a fraction 4/4, 3/4, 2/4, 1/4, 0/4 but it didn't take them long to figure the numerator is all they needed. From about 1934 or 5 on S=skeet choke.
Drew and Researcher,
Thank you. I just picked up a 1917 Flues 12 ga. marked 2 and 4 which should mean mod and full. The gun appears unmolested. Both bores measure at .717. Right choke measures .712 and left .695 so more like skeet 1 and mod. I found an Ithaca-source chart in Shotguns by Keith that says full is .693 and mod .711 very close to what I measured but the chart is based on a.729 bore. Any thoughts?
The British proof charts have showed 16ga @ .662" since way back about the mid 1800's when they worked out the tables. 17ga is .649" so a .650" bore would have been proofed as a 17 in England. Of course here in the US gunmakers were at liberty to make a bore size whatever they felt like without the necessity of it being marked for size. Early L C Smith specs do show the 16ga as having a .650" bore, but all other sizes are standard per the British charts.
My H grade Lefever bearing a 1907 patent date currently has bores of .669" in both bbls. I cannot of course attest they are original, but both bbls have 4+ inches of choke with .035" constriction (.634"). I really don't think it started life with bores .019" smaller than current. It is a rather high condition gun, not showing abuse or even very heavy use.
The thing that surpised me is that the bores measure .717 for a 12Ga. It's almost as if they were bored incorrectly (since the chokes compare favorably with published data from Ithaca).
I had an NID 10ga(mag, 500xxx) in my hands that was stamped with 4 on both flats...which I thought normal..but it also had a "PLUS" sign after the "4", it was an outline, not a line script like "+" but more like a Red Cross symbol.
Not seen that mentiond before?
Best,
Mark
That cross or plus sign is the mark of Charles August, meaning he proofed the gun.
That cross symbol meant that you will have to visit the local Urgent Care for a shoulder x-ray after firing that 10 ga a few times.