Parker gauge determination
 

Question--I just took my old Parker hammer gun to a well known sporting goods chain to see if I could find out the gauge of it. It was sold to me as a 14 gauge and I was curious to see if this was true. The man at the store, a 27 year veteran, tried to insert a 12 gauge measuring device into the chamber but it wouldn't go in. He then inserted a 16 gauge device into the chamber and it wobbled around with with a moderate amount of "play". From this, he concluded that the gauge was between a 16 and a 12, and probably a 14.
I read somewhere that to ascertain the true gauge of a shotgun, you had to insert a caliper device into the barrel and take a measurement at it's widest point and go with that measurement to determine gauge.
Someone did this for me a while back and determined that the gun is a 12b gauge.
Now I am TOTALLY confused! Which method is right? I would love for the 14 gauge determination to be correct and I feel that it is a possibility--the gun is early--serial number is in the 900's and barrels are decarbonized steel.
Any thoughts on this? Thanks!

What is the actual, complete serial number??

There are factory records on most Parker shotguns.





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Jack, read the faq http://parkerguns.org/pages/faq/12B.htm and pay particular attention to the last paragraph. I think this answers your question.... maybe?

Thanks!

Thanks, Robin. I am still somewhat confused (doesn't take much!), but what I think I'm hearing is some of the 12b chambers were too small to handle a 12 ga. shell???

Yes. 12b was brass shell. Which was thinner walled than a 12g paper shell. So the diameter of the chamber is smaller. Or you could have a 14g.

Accurate measurements of chamber and bore are the only way to know for sure.

My guess is that you need to measure the bore diameter (not chamber or choke area) to know for sure. According to http://www.hallowellco.com/bore_size_chart.htm you will measure .729 if its a 12 ga and .693 if its a 14 ga.

I found an interesting discussion on the A/B topic at https://forum.cartridgecollectors.org/t/16b-guage/9315 which my clear up or maybe confuse the issue.....?

Interesting topic none the less. That thread concludes with the following text:

All depends what you call the gauge.

If you are referring to it at the theoretical diameter of the bore (I am talking here about the British standard because US guns were following it in these old time)
we have for example
12 gauge = 18.52 (=0.729 inches)
14 gauge = 17.60 (0.693 inches)
16 gauge = 16.81 (0.662 inches)
20 gauge = 15.62 (0.615 inches)
From the chart I posted you can see the 12B and the 16B have these theoretical values.

About the A ctges, because there is a conical recess they also have the same bore diameter.
Therefore the assertion : 16 B and 20 A guns have a different bore diameter is false.

If you are referring to the standards the Brits used :
12 gauge can vary from 18.80 (0.740) to 18.03 (0.710) (this last one being in fact theoretical 13 Ga)
14 gauge can vary from 17.81 (0.701) to 17.20 (0.677) (this last one being in fact theoretical 15 Gauge)
16 gauge can vary from 16.99 (0.669) to 16.18 (0.637) (this last one being in fact 18 Gauge)
20 gauge can vary from 15.90 (0.626) to 15.14 (0.596) (this last one being in fact theoretical 22 gauge)
To which value is he referring in this case ??

If always at the same period you are referring to the US way of manufacturing I have no info about the spread.
Perhaps (and I think) the spread was narrower.
To which value is he referring ??

If he is referring to the nowadays US standard, we get :
12 gauge can vary from 18.92 (0.745) to 18.41 (0.725)
16 gauge can vary from 17.40 (0.685) to 16.89 (0.665)
20 gauge can vary from 16.13 (0.635) to 15.62 (0.615)

Conclusion :
Saying that this corresponds or not to a 20 gauge is pretty inaccurate.
You have always to tell the period of time, the standard and the exact value of what you call a 20 gauge bore.

Shortly, I would say that, taking into consideration the historical context:
a 12 B and a 14 A guns have the same bore diameter
a 14 B and a 16 a guns have the same bore diameter
a 16 B and 20 A guns have the same bore diameter

That stuff gets pretty complex and it takes a lot of experience to make a sound judgement. If the bores have been reamed - or even polished aggressively - NO conclusions can be drawn.





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A lot of early guns are oversized in the bores. So bore measurements alone will not give a true answer. If records are available, a letter is a good way to confirm original configuration.

Unfortunately in this circumstance, our records don’t go down into three-digit serial numbers.






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