REPRO CHOKE BORE DATA
 

I have never measured the bores or choke constrictions in my Parker Reproduction barrels until recently. I found the results interesting, especially that for the 12 gauge guns with Ic/M markings.
Both 16 gauge barrels are original Krieghoffs!

12G 28" Ic/M Bores .732" R .006" L .010"
12G 26" Ic/M Bores .734" R .006" L .010"
12G 26" Ic/M Bores .734" R .006" L .010"

16G 28" Q1/Q2 Bores .661" R .004" L .006"
16G 28" M/F Bores .661" R .018" L .024"

20G 26" Ic/M Bores .618" R .011" L .015"
20G 26" Ic/M Bores .618" R .011" L .018"

28G 26" Q1/Q2 Bores .552" R .003" L.006"
28G 26" Ic/M Bores .552" R .006" L .016"

Bob Jurewicz

The numbers match my guns exactly for the most part...I will add 410 IC/Mod is .006/.009 and 28ga. M/F is .014/.033 SXS ohio...(-:

Huh :confused: ?

The two 20 ga. IC/M barrels I measured are identical at 13 & 19 mils.

That is why I look for the Q1 and Q2 chokes in the 28GA. Perfect for grouse!!!!

Hello - I measured up my 12 ga. 2-bbl set when I bought it. Here's how the chokes actually measure:

28" M/F: Bore .735 R=.010 (IC) L=.035 (F)
26" IC/M: Bore .735 R=.008 (Skt) L=.012 (IC)

I was told by its previous owner that they are unaltered and the tapers all measure about 2". It is what it is and I actually like the set up. The 28" bbls are great in the dove field and the 26" bbls work well for grouse/woodcock.

Since it wasn't mentioned by the other posters, I will "mention" that the full choke constriction of my 28 gauge Repro is .039. I have no idea how the wad gets out of the barrel. Some day, I will shoot patterns with that barrel and report back. Parker Brothers full choke 28 gauge is .020. It will kill a single quail at 45 yards through brush. Our member Tom Flanigan witnessed that shot. He objected to my attempt to find the bird, so I sent my Wirehair, Eva, into the brush and she came out with the bird.

Good Grief man - that's a full choke measurement on a 12 gauge gun!!

Do you check for bulges after every shot with that gun?

How long is that choke boring?





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My 26" IC/M marked 20ga Bbls are:
IC/Right tube =0.016 or Mod to Imp Mod (0.624 bore)
M/Left tube = 0.018 or Imp Mod (0.619 bore)

The Kreighoff 28" 16ga Bbls I got from Tony are:
Right tube =0.019 or Imp Mod (0.671 bore)


M/Left tube = 0.030 or full+ (0.670 bore)

28 repro choke bore
 

On my 2 barrel 28ga. 26" IC/M .005 and .015; 28" M/F .015 and .035 yes, .035! I've not patterned it yet.

I was excited to trade a 26" single trigger pistol grip 28 gauge for "The Holy Grail;" a 28 ga 28" beaver tail straight grip double trigger. I couldn't hit a damn thing with it, so I measured the bores, and (from memory) "full" was almost 40/1000ths. I called it "silly full." So, I had a gunsmith open both bores to IC/IC. Suddenly, I could hit something with it. Do I now recommend doing that? Well, I guess I don't care what you do. My gun isn't going into a museum as long as I live. It shoots well at skeet, at doves, and I am pleased.
Sam Ogle

Very pleased to add to Bob's choke measurement chart:

16G 28" IC/MO Bore (R) .6632 (L) .6632 R .011 L .017
16G 28" Q1/Q2 Bore (R) .6631 (L) .6628 R .005 L .007

20G 28" Q1/Q2 Bore (R) .6225 (L) .6215 R .0065 L.009

What I'm seeing in this thread are a LOT of inconsistencies, even on guns of the same gauge and same choke stampings on the flats.





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During the time of Parker Repro production Japan's production technology was very good but product variation was common. For example: barrels are not universally interchangeable in each gauge; forend wood dimensions vary within gauge; shooting dimensions vary widely, etc..
The choke variations I see do not strike me as unusually excessive.
Bob Jurewicz

I do not have it anymore, but if I remember correctly my 28" 28 ga. Mod/Full was .016 / .039
The full barrel was rediculously tight, and I considered opening both up to about .004 / .012 for the grouse and woodcock hunting I was using it for, but never got around to it. Spreader loads seemed to do the trick for me, and I eventually decided to sell it in get me a non-repro 20 ga. for grouse hunting. Oh um and a real light PH 26" 12 ga. and a 16 ga. Trojan and just recently a lovely zero frame GH 16 ga. The quest for the perfect grouse gun continues...

I agree with Bob. I don't see excessive variation. Actually, in some cases, the consistency is quite impressive. My measurements, while precise, are not dead accurate only because I'm measuring point to point instead of taking a cylindrical measurement. Further, my point to point measurements do not reflect an average of dims measured across various points about the diameter. No shotgun barrel with a rib I've ever seen has been perfectly round.

We also must consider the variety of measuring tools.
Bob Jurewicz

Or more to the point, the variety of people using the tools.... after all, .001" is .001" and .010" is .010" no matter which tool you happen to be using.





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Dean, that's true (the variety of people using the tools) but the second half of your comment stating .001 is .001, not so much.

Yes, on it's face, you are correct - .001 is .001. The National Institute of Standards & Technology defines what .001 is. Fine. What most people don't understand as it relates to "size"; it sounds silly but "size" generally means nothing. Geometry is the key to measuring true functionality. Here's a photo showing several measuring tools that can obtain inside measurements.

I take my measurements using the green "Federal" bore gage. I position the gage & take my measurements north to south as the barrels are positioned proper. I can obtain a measurement out to 1/100,000th of an inch +/- with that gage. (splitting the graduations of 1/10,000th by eye). That's literally an inch broken into 100,000 equal segments for goodness sakes! Pretty precise? Not so fast! Drop the Comtor gage shown in the photo into that bore and compare that measurement to what the Federal gage says. It'll be smaller. Why? Because the Comtor gage is taking every variance of the bore such as an out of round condition, et al into consideration. The Comtor gage is telling you the largest size of a perfectly round shaft that will pass through the bore..THAT is true and bonafide accuracy! The Mahr bore gauge would be the second most accurate way to obtain a true measurement.

The Mitutoyo dial calipers, I suspect, are an example of what most people are using to obtain measurements. Trust me, that's not true precision but, it's close enough. The Federal gage I use, measures the bore in the same manner as the dial calipers however, it's much, much more accurate and has the additional advantage of detecting variances and geometric shapes in a manner the calipers simply cannot.

Scot, Aw shucks Scot, you know what I meant...

Actually, I was referring to the tools most commonly used by most folks measuring our shotgun bores and chokes. But thank you very much for that excellent dissertation. Are you related to Spencer? :whistle:





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If I recall correctly, Edgar was doing several mil per yr and in a cavalier manner decided to walk away from the biz b/c it was a pita. Further, he's got a killer gun collection.

DAD!!!..I'm your long lost boy!!! :rotf:

Scot, can you line those tools up left to right and tell us which is which? I have cabinets full of machine tools, cutters and measuring instruments and don't know what I have any more.

Well this is fun.....
 

I actually have an idea what those gizmos are...and going along with that when you start measuring for accuracy take into account just how long can I hold my hand perfectly still to get a "solid" reading? and what is the temperature of the room I am measuring in, how do I take into account thermal expansion, does it matter ? well yes and no, and yes and know.. depends on the kind of tool you use to split the hair and the type of surface finish I have achieved in my final process. Lots of variables to consider. ..as has been stated by others, that thousandth or two won't matter much if I point and shoot straight. I am always humbled by the fact that the Parker gun is such a Marvel of metal and wood, balance and artistry and has been for well over 125 years....I am still studying but I should get back to my chores..Happy Easter to All...Thanks & Best,Paul

Bill, just so this thread doesn't become inundated with technical jargon..I'll pm my email address. I'd be happy to help you sort through and identify the various items if you'd like.

I just measured a 20GA two barrel set that I just bought and it measures as follows:
26 inch barrels = RT .618 bore .010 Constriction, LT .617 bore .016 constriction
28 inch barrels = Rt .617 bore .016 Constriction, Lt .617 bore .035 constriction

I've always been impressed by how consistent the bores measure on these guns with very little variation.

26 inch barrels have 2 3/4 inch chambers
28 inch barrels have 3 inch chambers and both marked properly

Wow, .035 on a 20?! Extra extra full.

My new-to-me 12g DHE measured with my Skeet's bore gauge:

28" M/F: Bores .735", R=.011" L=.037".

Welcome to the forum Steven! Congratulations on your 1st post and your new-to-you 12-ga. How about doing a little show & tell in the "Let's See Some Wood" thread", please?

In the first post, Bob had the 12ga ic/mod at 6 and 10. Is that typical for all the 12ga repro's to be that open?

All of the 26" Ic/M barrels I measured were in that range.
Bob Jurewicz

That seems pretty open to me. Wondering what everyone else has for theirs?

I had a Steel Shot Special that a friend of Bob now owns with factory IC/M chokes that measure .006/.011.

I, too have a couple 12ga's choked IC/MOD with numbers consistent with Bob's.

As best I can gather, the 12ga Q1/Q2 chokes measure .003/.006 give or take. It would be interesting to know how they compare at the pattern board considering how open the IC/MOD chokes are.

This thread and a rainy day caused me to pattern my recently acquired 12 ga with 28" IC/Mod chokes. At least that is how they are stamped. I have measured them at .006/.012. I did not have enough time to do a thorough job of patterning but enough to get a good feel for how the chokes perform. I used loads that I have patterned in other guns so I have a feel for the loads capabilities. The patterns achieved were consistent with the choke measurements. The open choke came in at a strong skeet and the tight came in at light modified. A delightful clays combination.

12-ga. Parker Reproduction Sporting Clays Classic
* 28" bbls.
* Factory 3" Chambers (stamped 2 3/4")
* Factory Winchester Winchoke screw-in choke tubes.
* .734 bores
* CYL = .000
* SK = .003
* IC = .009
* M = .016
* IM = .019
* F = .029
* XF = .039