doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Measuring chambers New idea ???

Now we are getting technical when most of the guns talked of on these pages were made the English Trade worked in "attals" this is an obscure measurment system adopted by many trades and relied on the skill of the crafts man involved.A mixtue of basic measuring equipment and a "feel" for what was right. This was in the days before common use of micrometers and other high tech equipment.
The "attal"in fact was thus .That'al be right and That'al be good enough.

Thank You Gunman;
This "Attal" post effectively describes the conditions prior to adoption of SAAMI & CIP Specs & is the precise reason a single plug gage per Gauge size cannot be depended on to give an accurate measurement of chamber depth in all cases. In fact most of those guns in which it would be accurate will have chamber length marked anyway.

How accurate do you want to be ? How accurate do you need to be?
Provided the chamber is within the proscribed tolerances for purposes of proof, if that should apply,or unless you have a problem with ejection or exessive recoil etc., then yes you can use one plug to measure with. To be honest here folks I think there is a problm being created out of nothing. The original post suggested an a alternate way to measure chambers. The question I now pose is "how accurate are case lengths and diameters"?And does it realy matter providing the over all perameters are correct and within acceptable tolerances.

""To be honest here folks I think there is a problm being created out of nothing.""
Well now to be "Honest" Gunman, a discussion was being made in which various methods were being discussed of performing this job. All could, & have been, shown to give satisfactory accuracy, some as cheaply as $3.00 (My Scale) & some going to over $100.00 Those +$100.00 tolls are great tools if one has enough need for them.
You, Gunman (read Your Quote) were the one to come in & insinuate "ONLY" your way was good enough. It has I believe in fact been adequately documented, with reasons explained, that of all the methods mentioned "Your" method is the only one discussed that under certain conditions can be So Far off as to be totlly Useless. It is a great method if gage & chamber are properly matched, BUT remember we are dealing with guns which may go over 100 years old, form a half dozen or so country's & from a myriad of makers. They Ain't All got the Same diameter chambers.
So I ask you the same question you asked "How Good is Good enough". Well I have stated I can read a chamber depth with my little 6" scale to within ± 1/64". It has been explained how if that chamber just so happens to be .001"-.002" undersize your plug will read it .200"-.400" short. My answer to this question is ± 1/64" on chamber depth is quite sufficient for my purposes -.200" to -.400" is not. What's your take??
Certainly I have not espoused that it is a necessity to measure shotgun chamber lengths to within ±.001" or some other ridiculous tolerance. My discontinuance of using the plug gages was brought on entirely by the experience of actually using them & finding for myself their shortcomings. I am just trying to pass those findings on to others who may want to reconsider investing the time or money in obtaining a set.

Piper, I never said my way was the only way ,I stated that in my opinion it is still the best way. It may not be perfect in every case and some time you come across old guns with "tight "chambers that will not take a plug.But talking in general, based on over 40years of building and rebuilding double guns,I felt my comments may have some value to the debate.Take it or leave it, that like the method you use to measure anything , is your choice . In the course of my work I use a Chubb bore gauge ,a split ball gauge for chokes and a plug gauges for chambers. I dont see a problem as they are easy to use and as accurate as nessesary both in the sales shop or in the workshop when boreing, rechambering and when rebuilding barrels. There are always exeptions ,but thats life.

I have a Brownells 12Ga plug gauge and it usually comes up short in German shotgun chambers such as Sauers, Merkels and Simsons. These are guns made from the 1930s through the 1980s. That is even the case in guns marked 12/70. Most of these shotguns have .724 bores so everything is a little smaller than we're used to here. I have come to rely more on a good eye and an old steel 6" rule as was mentioned above.

But back to the original suggestion, that looks as if it would do just fine to distinguish a quarter inch difference in a shotgun chamber.

Gunman;
Once more "READ" your own post. There simply is no way to read into that anything other than you were saying the plug is the "ONLY" way to do it properly. That is the entire post quoted. Nice to see that you yourself do not follow what you said, but use other methods as circumstance dictate. Never-the-less from the above quote it did need to be pointed out the plug gage was NOT a Cure-All method which was infallible.

Remember everyone who monitors this board doesn't have the years of experience measuring chambers which you do. That post left the impression one could simply stick one of the chamber plug gages into any shotgun chamber ever made & if it came up short it needed "Fixing". That is not necessarily so. IF a 2 3/4" chamber "Gages" 2 9/16 just because it is .001" undersize "It Don't need Fixing".

Piper , It was never my intention to have a two sentence comment run on for days.

I see now that I should have made it clear that I was speaking in general terms ,but in my attempts to be both brief and witty I have failed .Without going in to long explanations of what I saw wrong with James'es original post,having had experience of a similar device and knowing its shortcomings ,not wishing to cause any offence to his ideas ,I made my original post that you have subsequently quoted.I still maintain that a plug gauge is the best method of measuring a chamber depth. Yes there are inherent problems and yes if you want to be 100% accurate you would need to measure the chamber diameter at the bottom and turn up a plug of the corresponding size taking into account that you can not put a .810" plug in a.810" hole,etc. etc.

In future posts I will try explain my reasoning in greater detail,so that my comments may hopefully be taken as helpful,rather than dismissive or dictatorial.