Miroku 700BC - from mid 1960s: Choke Identification

[MEHavey]

Troops,

My fathers' mid 60s Charles Daly import of the Miroku O/U (SN 203,xxx) has a bit of a mystery.

First: It has no Charles Daly markings -- only Miroku/Kochi
Second: All Google Guidance to the contrary, it has no Choke markings on either side of breech end of the barrel (See Pic-1)
Third: The Instruction Manual (somewhat worse for wear) says "Full and Full" on page-2
Fourth: The bottom of the barrel recoil lug recess says "IMP" (Pic-2)



My first thoughts are that the Bottom barrel is Improved, and the top either Improved-Mod or Full.
Any additional thoughts from the experts?

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[Jim Watson]

All I can offer is to get the use of a choke gauge to measure the constriction or to shoot the gun at a pattern board and count all the little holes.

 

[rbernie]

I used to carry these at gun shows:

https://www.brownells.com/gunsmith-...gauges/quick-check-choke-gauge-prod10984.aspx

 

[Speedo66]

My old 12ga. Springfield SXS will accept a 25 cent piece in one barrel and not the other.

Give it a try, at least you might determine if the chokes are different by how far the coin enters each barrel.

 

[MEHavey]

They're different -- about 15-20 thou by decent calipers.
But if I go by that, the bottom's MOD and top is FULL.

I did order a real choke gauge (thanks rbernie), so we'll see.

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[Jim Watson]

My old 12ga. Springfield SXS will accept a 25 cent piece in one barrel and not the other..

Wow, it must look like a blunderbuss. The old timers hereabouts use a dime.

Those little wedge shaped gauges are very approximate, they only measure the muzzle diameter while bore diameter and hence choke constriction varies a lot.

 

[Speedo66]

Wow, it must look like a blunderbuss. The old timers hereabouts use a dime.

Those little wedge shaped gauges are very approximate, they only measure the muzzle diameter while bore diameter and hence choke constriction varies a lot.

Right you are, not a quarter.

 

[jaguarxk120]

Checking with a dime does prove two things, first you have a dime,
and second it does not fit in the barrel, very old wife's tale.
Actual choke is the difference of the bore diameter and the choke diameter.

 

[Jim Watson]

But a dime is what they used, right or wrong.

I knew one old timer whose choke and aim test was to drop an empty shell box, pace off a distance I have forgotten, and shoot at it. He wanted four or five no 6s in the box.

 

[rbernie]

Actual choke is the difference of the bore diameter and the choke diameter.

It is absolutely correct that formal choke identification requires a measurement of both ends of the barrel, and that’s always worth pointing out. But it is also true that you can get a decent, if imperfect, understanding of the degree of constriction by measuring the muzzle ID and assuming a nominal breech dimension. It may not be the most accurate approach, but it gets you in the ballpark.

 

[Speedo66]

Checking with a dime does prove two things, first you have a dime,
and second it does not fit in the barrel, very old wife's tale.
Actual choke is the difference of the bore diameter and the choke diameter.

Since my particular SXS was not marked as to choke, using the coin method at least told me both chokes weren't the same, and which was the tighter one. The coin entered completely on one, only partially on the other.

That's all the info I was looking for.

 

[kudu]

Probably a modified and full. Right barrel is usually the more open as it is first shot, or front trigger, tighter choke on second shot or back trigger.

 

[243winxb]

Your gun came before my 1970s info.

Barrel length-
26" ic/mod
28" m/f
30" im/f trap gun, high comb. My guess?

The 1970s gun came from Japan & Italy.

Photos & info from 2 of my old books.https://www.thehighroad.org/index.php?media/albums/charles-daly-miroku-shotguns-1970.361/

 

[Bill M.]

I do not think the IMP stamped on the barrel refers to choke. A quick way to tell choke is to shoot a pattern at 20 yards and compare to a known choke pattern or look on the internet and see if you can find Jack O'Conners table from "The Shotgunners" book. Or have a gunsmith measure both the bore diameter and the choke diameter. My guess would be IMP and Mod but I have seen Miroku's that were custom ordered with different chokes. My friend had one that was improved and full from the factory.

 

[MEHavey]

Looking at other web pics (showing "MOD" instead of "IMP" (as on mine ), it does appear to indicate lower barrel's choke.

I did get THIS... which upon use actually indicates
>0.7045"<0.7145" on the Lower: ("~MOD")
>0.6895"<0.7000" on the Upper: ("~FULL")


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