doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Damascus small bore upland guns

Hi Doc06:

This is not exactly what you asked for but in one volume of Burrards 3 volume set he listed the results after he pressure tested several different English manufacturer's shells . I know he did it for 12, 16, and 20 and he may have done it for 28 and 10. He did it for different hull lengths. He gave low, high, and average values. The tests would appear to be done in the early 20s. He didn't state the results were in LUP (lead units of pressure) but I assume they were. In another section he gave a "curve fit" to convert LUP to actual PSI.

I was looking for what I think you are asking for for American guns. What average pressure shell was my 1920s manufacture English 16 gauge gun "designed" to shoot day in and day out - not the proof load, not the maximum load but the run of the mill every-day load.

I used the results from Burrard's test to decide what loads I shoot in my old British, old American, and old German guns. I have two of the books loaned out to my buddy Guion but I will post the tests, the book dates, and the conversion formula when I get them back or perhaps someone else on the board would be kind enough to post them.


Thanks!

Mike

We're all glad you're here too, AM, but I wish your pictures were elsewhere. They're the size of mural.

A little more input; According to an article by E H Harrison of the American Rifleman many years back while both Schultz (a bulk smokeless) & Ballistite (a dense smokeless) had been popular in both Europe & England for a number of years Smokeless powder shotshells were not factory loaded in the US until about 1893. BP had also been most commonly used for handloading. Many guns built prior to this designed almost in their entirity for use with black are lighter in their breeches with thinner walls over their chambers than later models. While I am aware that "Pressure is Pressure" I am also aware that black powder is less sensitive & more forgiving of slight errors than is smokeless. For this cause, & realizing some may disagree, if the min bbl thickness over chamber is not at least .090" I personally restrict that gun to the use of black powder. In this same series of articles the invention of the "Pressure Gauge" (crusher) was credited to Thomas J Rodman Ordnance, U S Army, but date not given. He was also credited in 1860 as a Major (later General)of developing a means of controlling the burn rate of black powder for use in large guns by compressing it into a more solid mass to slow it's combustion. The compression was said to limit burning much more than mere granulation size, which had "Only Limited" effect. I suspect the pressure gun was in use well prior to 1900.

AM,
I appreciate the effort and when you do get the volumes back, I look forward to the post.

Pipe,

Again, thank you for the info. The wonderful part about owning guns like these is learning the history of the era in which they were made. It adds that extra dimension to gun ownership, other then appreciating them for the works of art they truly are, you become connected to a part of the past that most others will never know.

The "Rodman Gun" was used during the civil war.

I can well imagine he needed to control the burn rate of black powder. It was an 80-ton cannon, the largest in the world at the time.



While pressure guns may well have been around for a long time, I think the question still remains, "When did pressure supersede loads for proof house standards?"
Certainly into the mid 1920's proof was done by load.

Pete

Small bore indeed!!!

Doc; Will have to try to do some more digging on this, but generally I think pressure began to supercede load for proof shortly after the introduction of smokeless proof. W'with BP the pressure was actually pretty well controlled by the load, but this was not true with smokeless. This has often been stated to be the reason so few pre-1912 German guns bear Nitro Proof. German proof law at the time required proof "By Load" with whatever powder was used for proof. This resulted in a "Very Severe" proof when smokeless was used, so few makers submited their guns for "Nitro Proof". This changed in 1912 with the law being re-written for nitro proof to be done to a pressure level rathar than by load proportion. Some other nations I beleive were already doing the same, in fact may have been done from the beginning of Nitro proof in England. These pressures were not always necessisarily published, but the proof athorities & gun makers new them.

I was looking for something else in TPS and ran across a chart that Parker Brothers supposedly used to determine pressure for proofing. It was based on British rules for 1925. It lists definitive proof pressure, service working limits for factory loaded ammunition, etc for gauges 410 thru 10. It dates back to 1934, it is on page 515 in The Parker Story. I will scan it, any one that wants a copy e-mail me.

The hoop stresses in a small bore gun are lower than those of a larger bore with the same gas pressure and same wall thickness.

In other words, the smaller the gauge, the higher the pressure the gun will take, with the same wall thicknesses.

Doublegunhq,

Please explain.