Poor man's bore gauge?
 

Is there any such thing? I would like to determine the actual choke in a couple of my guns but I really don't want to invest a bunch in a bore gauge; just don't think I'd have that much use for it after the initial use. Most of the inexpensive inside calipers I've seen probably don't go deep enough, and most aren't accurate enough either. Any suggestions? Thanks...

Gary Bulley only charges $140 for a dial type bore gauge - a little more for a digital and he is a nice guy to deal with

https://www.theunloader.com/

if I charged $5 for every bore I measure for someone else - both of my digital ones would have paid for themselves

if you really have no further use for it - i'd bet someone here would buy it for a few dollars off

An inside caliper can measure the inside of a bore can work to measure constriction. I have seen them with spring loaded legs that are maybe 4-5" long. You can use them for choke and also chamber length gauging.

That would likely be your best option at an "economy way" and still use accurate equipment.

Like these...

Attachment 86569

Attachment 86570

Brian, my only problem with those is that unless you want to pay a pretty good chunk the ones I've looked at say accuracy is around +/- .01. I didn't think that was good enough. Maybe I just wasn't looking at high enough quality ones?

I frankly don't know anyone who gives a sh!t about the bore diameter of any gun they own, so that sort of payback is out of the question :). That said, assuming I decided to pop for one of these, what's a good length to get? And is it worth it to pay the extra $35 for digital?

its always the chokes they want to know about.

length wise - i like 18" a little room to spare if I want to completely measure a 32" set of barrels.

I like using the digital- but the draw back is - always remember to have a spare battery around. but I also have a dial bore gauge, and it works absolutely fine -

so the answer to that is - personal choice - no practical advantage

So excuse me for bein' dumb, but...you can measure the choke constriction with this as well, right?

Well I want to know bore diameter, first you can't know the choke without knowing the bore diameter, second it can give away barrel work such as back boring or excessive bore clean up.

yes. insert it from front of the bore and as you slowly draw it out, the gauge's reading will drop - so, the points of constriction is the difference between the inside bore diameter and the reading at the muzzle. you can tell the length of the choke by when the numbers begin to drop.


to use the gauge - you use a ring that comes with it to zero it - the inside of the ring is .700 for the 16 to 10 size. so when you drop the gauge in a 12 ga for example and it reads .029 that means the bore is .729. if it reads -006 at the muzzle - the choke is .035

simple once you have done it a couple times

Phil, if you’re only interested in one-time use to measure the bores and chokes of your guns, I’ll loan you mine.

I have two but they will not measure 10 ga. Or .410.

If you want to borrow mine just shoot me a PM.

Dean





.

Mike Franzen has one and he's a wizard with that thing.:)

I have measured Parker chokes that were a bit over 6” long.





.

Buy a bad gun and then complain about the price of a $110 bore micrometer. End of story. My bore micrometers and wall thickness gauge are more than 20 years old and have measured a million dollars worth of good and bad guns for me and friends. The gauges cost about $300 for all gauges, one Manson wall thickness gauge and two Skeets type micrometers. Never believe a dealer when he says he doesn't own a bore micrometer. He owns a bore micrometer. He buys guns with the micrometer and he sells guns without admitting that he owns a micrometer. Have you ever noticed that a dealer, when asked what the chokes are, his reply is "IC and MOD" for guns with barrels under 30" and "MOD and FULL" for guns with 30" and longer barrels. His job is to sell you what he thinks you want, without measuring the bores.

They are the same dealer that doesn't have a magnifying glass handy when you're looking at his gun.

Are you sure about that number, Phil? Even the Chinese junque at Harbor Freight states, and is, more accurate than that.

I prefer mechanical gauges over digitals, and as Rick says, keep (a pack) of batteries handy; they eat them.
Mechanical gauges with a telltale make meaningful measurements easier. Digitals have a zero function, but when you zero, your previous measurement is lost.
When we were certifying to ISO 9001, digital gauges, on almost every measuring instrument was considered a secondary measuring tool.

Phil, are you sure of your measurement? .01 is one hundredth of an inch. A good machinist with a scale can identify .01. We are talking about cheap micrometers that will measure one thousandth of an inch.

I was wondering the same thing. I think he means .001.
In that case, that would be plenty accurate for measuring choke and bore diameter.

Here's one selling for $60:

Features
Robust housing.
Large LCD display.
Reading: .01" / .1mm / 1/64ths
Accuracy: .01" / .1mm / 1/64ths
Length of arms: 4"
Spring loaded with locking nut.
Battery: CR2032

Here's one with better accuracy; it costs more than a bore gauge :):

Minimum Measurement (Decimal Inch)
0.3750
Maximum Measurement (Decimal Inch)
1.3750
Graduation (Decimal Inch)
0.0010
Accuracy (mm)
0.0380
Accuracy (Decimal Inch)
0.0015

Phil if low cost is the main concern to achieve accurate measurement then consider telescoping gages 3/8"-3/4" and 1" outside micrometers. The low cost items are made in china but accuracy is easily within .001". Amazon, Harbor Freight, and MSC are places to look. This way of measuring is cumbersome but will meet cost and accuracy requirements.

If the data is saying the accuracy is the same as the readout scale, I'm going with misprint. I doubt anyone would even bother marketing something with pathetic specs like that

As I posted before, I can measure 1/100 of an inch with a good school ruler or a machinist's scale.

I'm not questioning anyone's abilities with a ruler or anything else; just relating what I found, hence my statement.

My 2 cents worth, spring loaded bore gages, expand take out and measure with a micrometer work shallow & take some pratice to use properly. Have a set never use them, can’t get repeat consistent Measurements. Chinese and cheap, Starrett set may work better.

Inside micrometer is easy to use and accurate. But is also shallow, 1/10 inch or so from the muzzle. Think I paid 60-70 bucks for my Mitutoyo inside mike used. New double that price. Use it a lot general shop work, not on shotgun barrels. Have a Mitutoyo tubing wall thickness mike too, useful but again 1/10 or so deep.

Deeper accurate enough not real expensive the Skeets Gage its the one I use on barrels. Wall thickness I get somebody else to measure for me. Would buy one if I saw a deal.

Never owned one of the inexpensive dial deep calipers. Opinion without experience would not bet a Chinese 5 inch deep dial is as accurate as a Skeets & for sure won’t go deep enough.

William

I think I've talked myself into an Unloader gauge (or maybe you all are responsible for that), despite Dean's very generous offer to loan me his. Now deciding on length and whether to go analog or digital.

Wise decision. Were I buying another one today, I'd still buy an analog dial indicator.

Thing about digital is the battery. I only use one Digital in my shop, Mitutoyo Caliper, and keep spare battery’s to fit, its a good tool & use it frequently, switch to metric & back quick is advantage. Still have Analog Imperial & Metric Dials and often used Veiner caliper for working in fractions.

If I went digital for everything would need many different battery’s & for sure infrequent use likely to be dead when I need it.

Digital no more accurate than quality analog either. Actually one good vintage Mauser brand caliper imperial thousands & fractions one side Metric the other serves all purposes. Inexpensive used on EBay
Look at this one 154025842685

William

I have both analog and digital measuring instruments. For bore and choke measuring I prefer analog (dial type). I like watching the needle swing back around the dial as I enter the choke constriction, and seeing how quickly or slowly it moves. Skeets is a very good gauge.

For weighing I prefer digital.

JMO, SRH

Stan you hit the nail on the head. You are able to visually see the relationship of changes as you're measuring. I feel the same about digital watches, and clocks. You would be amazed at the number of children who do not know how to tell time, and only know what time it is, right now.

I was mentioning this to a good friend of mine, and he just gifted me this nifty little device. Made in Germany, and finished with all the precision you'd expect from those folks; it feels like a fine engineering instrument (which I guess it is). He doesn't remember where he got it some years ago; possibly Browell's. Pulling the knurled handle releases the three spring-loaded ball bearings which then expand to fill the bore. Pull it back to the point of greatest constriction, read the gauge. Viola! While it won't give me decimals it will definitely fill the need I have at the moment. I may still buy a gauge at some point. Or maybe not.

https://i.imgur.com/K4BsB3xl.jpg

Phil, I have 2 of those, although they are neat and I used them 30 years ago they are not that accurate. Better than nothing but they can't compare to my Stan Baker set that measures 10 to 410.

I have one of those also. One of several gauges I have.
They were made in Germany and marketed by Frank Mittermeier out the Bronx, NY. They appear in a few catalogs from the 50’s and 60’s.
Copy of the instruction is attached.

I'm sure that's true James. Price was right though :)!