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Riflemeister
PostPosted: Mon Jun 06, 2022 5:24 pm  Reply with quote
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The link below is the 100 Straight bore gauge set I use, but I added a 16 ga measuring head and setting ring to the set. I've been using it for over 10 years on my shotguns as well as customer's guns and have found it to be very accurate and easy to use. It is very revealing what you find measuring bores and chokes. I recently measured a Franchi 48 barrel marked "skeet" that measured out as light modified. Of course there is no substitute for patterning the chokes in question with the loads you intend to use. Probably more surprises from patterning than measuring.

https://www.brownells.com/gunsmith-tools-supplies/shotgun-tools/bore-gauges/complete-dial-bore-micrometer-set-sku365001000-6808-16684.aspx

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double vision
PostPosted: Mon Jun 06, 2022 6:26 pm  Reply with quote
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Riflemeister, you aren’t kidding about what a bore gauge can reveal. I once sent a new set of expensive barrels (Merkel 1620) to a guy on the east coast. Many rave about him and his prices. The right barrel choke was so rough the needle on my bore gauge bounced around like a Geiger counter. On top of that the exit constriction was exactly twice as open as I asked for. So then he must have thought he could cover it by jugging the choke, and it was rough. Not much I could do about it as he didn’t return my calls, but I will steer clear of him thanks to having a bore gauge.
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Builder
PostPosted: Mon Jun 06, 2022 6:47 pm  Reply with quote



Joined: 21 Mar 2013
Posts: 111
Location: Northern New Jersey

Does his last name begin with an "O"?

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double vision
PostPosted: Mon Jun 06, 2022 6:58 pm  Reply with quote
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Builder wrote:
Does his last name begin with an "O"?


By golly I believe it does.
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double vision
PostPosted: Mon Jun 06, 2022 7:00 pm  Reply with quote
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Builder, it was nice to chat with you the other day and compare and notes on this and moving patterns.
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WyoChukar
PostPosted: Mon Jun 06, 2022 9:48 pm  Reply with quote



Joined: 16 Jul 2015
Posts: 2124
Location: Hudson,Wy

There is one more way to measure choke, choke profile, etc. I didn't mention it earlier due to expense and the expertise needed to get accurate readings, but a wall thickness micrometer is very revealing and can be rather useful when evaluating the safety/ internal condition of older gun barrels (particularly thin ones).

Yeah, yeah, I know getting a bore gauge is simpler and less expensive, but it won't tell you if a vintage barrel set is well out of concentricity or dangerously thin somewhere. I'll admit mine cost far less than what they sell for (or a bore gauge for that matter) since I built my own.

Using one does take practice and consistent technique to get repeatable results. It did however save my bacon on that ill fated Parker passed off on me by Griffin & Howe a couple years ago. I also find it useful for determining whether a set of barrels can safely be altered (chamber length, forcing cones, etc.).

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Researcher
PostPosted: Tue Jun 07, 2022 1:11 pm  Reply with quote



Joined: 13 Jun 2009
Posts: 695
Location: WA/AK

All this talk of measuring is nice, but choke is defined by the percent of the intended load in a 30-inch circle at forty yards. I know measuring is easier than shooting patterns, drawing 30-inch circles and counting hits.

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WyoChukar
PostPosted: Wed Jun 08, 2022 8:08 am  Reply with quote



Joined: 16 Jul 2015
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Location: Hudson,Wy

I was going to mention patterning the gun...but it is to be taken with a grain of salt since patterns vary tremendously with load quality. It's the one true way to know what "choke performance" the gun is producing with a given load and if this is the goal, the only way to go. But if one needs to quantify barrel measurements, measurements they need to be.

Case in point. With modified choke I can produce I/C patterns with chilled shot and high velocities. I can get modified choke performance with my standard loads using magnum lead. I can get full choke performance with proper buffered lead loads or steel shot.

This is great, but still doesn't give me a comparative measurement of constriction. This may or may not be any great concern, but if one wishes to list a gun for sale, perspective buyers will want to know "what choke the gun has" since it has bearing on intended use of the gun.

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Cold Iron
PostPosted: Wed Jun 08, 2022 12:32 pm  Reply with quote



Joined: 09 Mar 2016
Posts: 746
Location: Mn.

What WyoChukar said. I have patterned thousands of rounds. Not so much anymore since Shotgun Insight no longer works now that Java has been locked down and can't import pattern pictures to do the counting for me. Even then you had to still count pellets by hand before firing a single shot. In at least a couple of shells.

Patterns are a statistical average. I subscribe to the school of thought that it requires at least 10 shots. Even doing only 10 it is not abnormal for the pattern of those 10 shots to range a full choke size, from IC to Mod for example. With the same shells on the same day in the same gun and same choke.
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16gaDavis
PostPosted: Thu Jun 09, 2022 7:44 am  Reply with quote



Joined: 24 Jun 2013
Posts: 2062
Location: canandaigua - western n.y. (formerly deerhunter)

The only thing i like about snow now is it's my pattern board . I pick a mound out there , shoot at it to check POI and then determine if the grouping looks tight or loose - close enough !

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putz463
PostPosted: Sat Jun 11, 2022 3:58 am  Reply with quote
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Sharing, measuring a new to me Zoli O/U with listed (by Cabelas) chokes being F/IC. Now in hand, when just measuring the muzzles the chokes run out at 641/657 and then referencing the standard 0.667 bore = .026/.010 constriction ~F/S2 close enough, but then measuring the bores at .671/.674, the 641/657 chokes are 030/017 (in writing) look more like XF/M. All fine and well but I'm firmly in the camp that Reasercher mentioned in that that actual choke is an exercise in reverse engineering, being, what shows up on the pattern paper (not written) is what the actual choke is. Not whats printed on the tube or barrel alone.

Greatly looking forward to spending some time at the range doing some reverse engineering with this Italian beauty. Cool

Bill, I've done (had to do) the snow pattern testing thing as well, it works. It chronicled why hunting my 24ga (XF/F) on that first outing was either a complete miss or a glob destroyed meat. OK, got let'em get out a bit.....

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MaximumSmoke
PostPosted: Sat Jun 11, 2022 11:26 am  Reply with quote
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Putz463 -- Standard 16 bore is 0.662", not 0.667".

We see published all sorts of bore sizes touted as "standard", especially for 16 gauge, it seems. I'm sure it's not news, but the diameter of any given shotgun "gauge" equals the diameter of the balls of pure lead, the "gauge number" of which weigh a pound. e.g. For the 16 gauge, bore diameter is the diameter of a ball of pure lead (0.4097 lb/cubic inch) weighing one sixteenth of a pound. It takes the "gauge number" of such balls to make a pound -- 16 in this case.

One can go through the math to check. To aid your calculations, the volume of a sphere is (Pi/6) x Diameter^3. Here's a little table for reference on all sorts of cartridge and chamber dimensions for shotshells:

http://www.dave-cushman.net/shot/shotshellloads.html

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Winchester21
PostPosted: Sat Jun 11, 2022 8:55 pm  Reply with quote
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Location: So Cal

What I use are "Inside Calipers". some of which have a dial, but mine don't. They are spring loaded and are expanded or contracted by a screw adjustment.
It takes a little practice to feel the maximum expansion for the inside of the barrel or choke and tighten the screw down so that the arms of the caliper just barely make contact. It takes a little practice to get the right feel and setting but it's easy to do.
Once you've found the max dimension inside the barrel or choke you remove the inside caliper from the barrel. If the tool has a dial indicator you're good to go. But if you've got non-dial ones then it's simply a matter of measuring the max spread of the arm tips with a regular (outside) caliper.
All you have to do now is look at the difference between the bore diameter as compared to the choke diameter to determine the amount of choke constriction.
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Pine Creek/Dave
PostPosted: Sat Jun 11, 2022 10:22 pm  Reply with quote



Joined: 17 Mar 2017
Posts: 2787
Location: Endless Mountains of Pa

Gentlemen,

I do believe the shells you choose to use are more important than the exacting choke measurement. Although chokes are important the exact measurement is not. Your pattern will change with the shells you choose to use, even with the same choke in the same gun. If you have screw in chokes choose which choke you want to use and find the shells that produce the patterns you want, at the yardages you shoot at the most. In my case that is between 28-40 yards, in the Grouse woods. Using the SpredR shells in the 1st barrel and regular shells under the 2nd trigger covers the 25-40 yards I most gun birds at, over my Grouse dogs. You must find the bird killing pattern that is best for your kind of gunning, by patterning the shells you are going to use in your particular gun, choked in the manner best for your gunning.

all the best,

Pine Creek/Dave
L.C. Smith Man

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putz463
PostPosted: Sun Jun 12, 2022 2:52 am  Reply with quote
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Thanks for the correction Cold Iron, so 021/005 and depending on which choke chart one looks at puts it in the M/S1 category w/o measuring the bore. But back to beating dead horses, the real designation will be what shows up on the pattern paper with which particular loads I choose to send down range.

I've read about and understand the lead ball gauge designation thing, interesting bit of history. Kinda of find it also interesting that the weight of any one of those individual balls, in loose terms, tells the loading sweet spot for the particular gauge, 1/10lb = 1.6oz in 10ga, 1/12lb = 1.33oz in 12ga, 1/16lb = 1oz 16ga and so on.

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