Determining a fixed choke size, Ithaca

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Pyd

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I have an Ithaca M-87 (same as 37) with a fixed choke, is there any markings/stamps they use to help determine the choke size?

Thanks!
 
Should be marked somewhere on the barrel. Seem to recall the ithica was fairly straight forward and used the words full. mod. or Imp, Cyl
 
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I did that, it was the same as the "full" on my Remington, around .77 if I recall. I thought there was more to it than that. If not than I have already answered my question. I sent Ithaca an email a while ago with no response.
 
Here are some muzzle constriction numbers that refer to Remington shotguns.

Full: .691
Mod: .709
Imp: .718
Cyl: .732
Imp Skeet: .725
Skeet: .732

Regards.
 
The proper way is to measure the bore and then measure the choke and determine the amount of restriction. .77 wuld mean that the choke is probably wider than the bore?

or you could drop a dime down the bore:p
 
I am using a set of Mititoya calipers, I have no way to measure the bore.
I just measured again, the Remington is showing .70 and the Ithaca is showing .72, provided of course I am doing that right.
.77, I should have caught that, oops.

Is there a bore measurement tool I should look in to?
 
I think you're pretty much there, give or take a few thou. Not easy to measure exactly from one end of a tube to the other.

Seems you're somewhere in the Modified zone.

The figures I mentioned above are from Remington themselves, my 870 MOD measures .715, the barrel is marked MOD. So there are differences even within the same manufacturer. My Improved is .720. ... :) I have notes handy of all this in case you wonder where I'm getting the numbers. :D
 
Choke is determined by the difference between bore diameter and muzzle diameter. Unfortunately you can't assume that bores are standardized, and Ithaca bores are known to be tighter than most others. The only sure way to do the measurement is to use a good tool like a Skeet's bore gauge. I have one and they work well, but kinda pricey at US$90. They can be purchased at Brownell's, to go to the item on their website, just put a www. ahead of this web address... brownells.com/aspx/ns/store/ProductDetail.aspx?p=12736&title=SHOTGUN%20BORE%20GAUGE. A good shotgun smith should have the tools required to do the measurement, and could measure for you.
 
Longwalker said:
Choke is determined by the difference between bore diameter and muzzle diameter.
Click to expand...

That just determines the amount of restriction between bore and choke. Choke is determined by the density of pattern actually thrown by that restriction. The standard test in a 30 inch circle at 40 yards. Pick the load you wish to test. Count the pellets in that load. Shoot at paper at 40 yards. Scrible a 30 inch circle with the centre at the most dense point. Count holes. Divide the number of holes by total pellet count. The resulting % will tell you what choke you have. Best to do an average. Actual percentage may vary, depending on load. Though tedious, it is a lot quicker than sending for a gauge and a lot cheaper as well. Also a lot cheaper than taking it to a smith unless the smith is a kindly old fart that just likes to educate, and there are some like that:D

or

you could drop a dime through the tube. If it passes, it is meant to be less than full. If it is less than full, it is probably a modified, because ithica usaully made their imp, cyl. with 26 inch barrels, and improved modified is rare in factory made ithica guns that were not designed for targets. The dime test is only a full choke detector in american made guns around the time of the m37.
 
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Covey, you're right of course. The amount of bore restriction is only a way to predict pattern %, but it is a pretty good one.
Hallowell co. has a useful chart of standard chokes, makers markings and bore restrictions. Just put a www. ahead of this address in your browser...
hallowellco.com/choke_chart.htm
 
Thanks guys, I was thinking the gun was a military or police version and I assumed the choke would set accordingly, whatever that may be.
I lent my Remington out during the shotgun hunt here and took that Ithaca to the range, it seemed to have a fairly tight pattern, or at least tighter than I had expected.
I would like to use it to hunt, but wanted to know the restriction first, I suppose that is unimportant if it patterns well.

*edit* the dime slid clean through.
 
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OK, so if it were a full choke where would the dime have hung up in a fixed barrel? At the end where a choke tube would rest or sooner?
 
Pyd said:
OK, so if it were a full choke where would the dime have hung up in a fixed barrel? At the end where a choke tube would rest or sooner?
Click to expand...

I just tried it with a 870 30 inch full and the dime came to a stop about 1.25 inches from the muzzle. I would expect it to be different measurements depending where each manufacture starts the choke and the different degrees of choke. I have tried this over the years with hundreds of remingtons and winchesters and full would always stop a dime.

A dime will not pass through an invector plus full or an optima full or an optimas imp. mod. but it will pass through in invector plus imp. mod. Nothing scientific about this. Just an observation.
 
Interesting. I had it in the back of my mind that the barrel would start to restrict almost right away on a fixed choke barrel, gradual toward the muzzle. Now having thought about it I think that would be far more difficult to machine.
Glad I asked, I am still going to get that measurement tool though.
 
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