Poor man's bore gauge?

[John Davis]

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

[Dean Romig]

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





.

[Bill Murphy]

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.

[edgarspencer]

Originally Posted by Bill Murphy

Never believe a dealer when he says he doesn't own a bore micrometer.

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

[edgarspencer]

Originally Posted by Phil Yearout

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?

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.

[Bill Murphy]

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.

[B. Dudley]

Originally Posted by Bill Murphy

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.

[Phil Yearout]

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

[Craig Budgeon]

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.

[edgarspencer]

Originally Posted by Phil Yearout

Reading: .01" / .1mm / 1/64ths
Accuracy: .01" / .1mm / 1/64ths

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