doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com B&P 16ga Vintage loads

Stan, ignorance permits popularity of bigger-boom-is-better.

Yeah, we're all about bigger and faster being better in the USA--unfortunately.

You have to be careful converting both pressure and velocity data on foreign shells. 1300 fps sounds pretty hot . . . but I know the Brits sometimes use true muzzle velocity (we measure at 3 feet), and that makes a significant difference. Don't know whether the Italians do the same.

Pressure . . . you have to know whether they're using lead crusher measurements or piezo-electronic. You can't convert from one to the other. No formula.

Sometimes, even when we're speaking English, there's confusion from this side of the pond to our friends across the water.

Ken, here's another vote for RST. They're good in terms of both pressure and velocity. They'll be fine in your son's Flues.

Larry, do you have an example of a gun with measurements tested by both piezo-electronic and lead crusher measurements? Gil

Just trying to give Bro. Larry a hand

Major Sir Gerald Burrard published an estimated LUP (Long) Tons/ Sq. Inch (TSI) to piezoelectric transducer Pounds/ Sq. Inch (PSI) conversion formula in the Third edition of The Modern Shotgun, 1955, Vol. 2 derived from simultaneous crusher and transducer pressure readings in a test barrel.
He observed the under-reporting of pressure by (crusher) LUP compared to piezo transducer gauges:
�The calibration of lead crushers by means of the piezoelectric gauge suggests that lead crusher pressures are somewhat on the low side; 2 Tons per square inch being about 2.5 with the piezoelectric gauge��

Estimated Long Tons Per Square Inch Lead Crusher Pressure (Cp) conversion to PSI (pound force per square inch) (Cp x 1.5) - .5 = TSI, TSI X 2240 = PSI.
Using this formula:
3 Tons/sq. inch by LUP (crushers) = 8,938 PSI (pounds/ sq. inch) by transducer

SOME turn-of-the-century pressures however were reported as PSI by LUP rather than Tons/sq. inch as measured by LUP, so Burrard's formula cannot be applied for conversion.
We have no conversion for PSI as measured by LUP to PSI as measured by transducers, but adding 10 - 14% to the load pressures reported as PSI by LUP is a reasonable estimate.

To be clear, CIP reported pressures, adopted in 1969, as BAR ARE measured by piezo transducers. BUT the darn Brits didn't adopt the CIP standards until March 1, 1980.

The long version is about 1/2 down here
https://docs.google.com/document/d/1F2sQuPm05IE4VWYYnCkvuXmYEzQoWd_SQgaAfUOZEFU/preview

I will state a few points here as I have come to understand them. The Piezoelectric transducers give a virtually instantaneous reading so record actual PSI. Lead or copper (used for higher pressures if rifles)) crushers were calibrated to a known pressure & their amount of crushing measured.
Problem was the time of "Peak Pressure was so short the crushers were not reduced in length to the full amount of the actual pressure applied, thus they always read light.
As to Burrard's formula he was quick to point out this was not linear, but was close enough within the confines of ordinary shotgun pressures. I will add that I do not think we can guarantee that a 3 ton British & a 6,720 US LUP is actually identical. I do not know for a fact that both countries used identical alloys for their crushers or that the calibration procedure was identical.
Burrard's formula thus in my opinion can only truly be considered basically correct in relation to British crusher pressures.
I have seen some rifle data where both PSI & CUP pressures were listed. Some of the "Hotter" magnum loads showed a considerable difference while some old timers as the .45-70 showed only a slight difference. I doubt seriously that the variations are as great in shotguns.

The problem is which Tarage Table the various countries were using, prior to the 1969 CIP standardization

British Crusher Gauge illustration
https://books.google.com/books?id=inQCAAAAYAAJ&pg=PA29&dq
Tarage Table
https://books.google.com/books?id=inQCAAAAYAAJ&pg=PA37&dq

Wallace H. Coxe, in �Smokeless Shotgun Powders: Their Development, Composition and Ballistic Characteristics� published by E.I. du Pont de Nemours & Co., 1927, �Measurement of Pressures�
The common method of taking pressures in small arms in this country is known as the Radial Pressure system. A housing is built around the barrel, and a hole drilled through the housing and barrel into the chamber at a distance of 1 inch from the breech and at right angles to the axis of the bore. The hole is then bushed and drilled to a uniform diameter of 0.2250 inch. Then a piston is made the length of the piston hole and 0.2250 inch in diameter. Next the piston hole is lapped to permit the piston to fit snugly without either sticking or getting out of alignment.
In firing the gauge, the piston is inserted and seated, then a lead crusher cylinder is placed on the head of the piston and held firmly in place by a screw and anvil attachment built into the housing. When the cartridge is fired, a portion of the same gas pressure that pushes the bullet through the barrel drives the piston against the lead cylinder and compresses it.
The length of the lead crusher cylinder after compression is naturally less than before the shot was fired and the difference between the original length and the length after compression therefore represents the amount of pressure which has acted upon the lead. Thee exact pressure is read from a table giving a pressure reading for every remaining length reading and commonly called a Tarage Table.
Pressures that are determined at ballistic laboratories are merely relative values and are not absolute values.

NOTE: The Tarage Table conversion may be for pressure expressed as Tons / Sq. Inch or Pounds/ Sq. Inch (PSI).

Owning a 16 gauge gun is the best argument I know for reloading your own cartridges. I own (and shoot) several 16s.

I often shoot a 5-1/2lb. Harkom 16 with 2-1/2' chambers and proofed for 7/8 oz. loads. For low pressure loads, I shoot AA hulls with 209P primers, R16 wad, and SR7625 powder.

I love 16 gauges! You will love the rst and Polywad shells. No matter the length of shell an ounce of 8's is an ounce of 8's

Ken,

B&P makes only one 16 ga load that they import to to US and they are firecrackers as well as deadly... but they are nearly 9,900 psi. I love them on pheasants in my AYA but even then in the 2nd barrelo nly.

Here is their pressure chart:
http://carolans.com/R/bp-1/content/Speed-and-Pressure-Chart.pdf

That said, I have had great success with RST 16s in #6 copper/1 oz on SD roosters thru my vintage Cashmore. My MN kin folk are constantly amazed how I can fold 60 yard crossing roosters with that little "pop gun" while they are banging away with 1 3/8" of high velocity 4s in 12 ga autoloaders.

The answer is SHOOT THEM IN THE HEAD. Don't take tailpipe shots. When I walk to push a field I seldom shoot, saving my shooting for outside or end blocking. The Brits truly understood a thing or two about how to dispatch Mr. Phez!

Dr. P

Thanks everyone for all the input. I think I'll err on the side of caution, and go with either RST or Polywad. The Flues is in really nice shape and fits him perfectly. Once I recolor the action and barrels it'll look like new. I want him to be able to pass it on one day.

Regards
Ken