In order to participate in the GunBroker Member forums, you must be logged in with your GunBroker.com account. Click the sign-in button at the top right of the forums page to get connected.
Options
English shotguns
rrp5
Member Posts: 10 ✭✭
I just bought a Midland hammer gun made in 1890 sxs 12 bore. It has been re proofed for 70m/m or 2.75 inch shells in the mid 80's and it has a stamp of 3 tons per sq. inch. There is no mention of ounces of shot, such as I have seen on some English sxs. With a pressure rating of 3 tons, that seems to be exceeded by anything even the light trap loads using 1 oz. of shot. Does this mean it is not safe to use high velocity shells rated at over 11,000 PSI?It is a dream to shoulder, I just don't know as to whether or not to tell my friends to stand back every time I shoot it! Thank you for any help you may be able to give me. RRP5
Comments
Unfortunately, there is essential NO formula to convert BAR expressed as LUP (CIP) to PSI (SAAMI). LUP + 1000 does not reliably predict the actual piezoelectric transducer measured pressure.
In 1989, all proof data was marked in metric using the BAR as the unit of measurement. The use of TONS per sq. inch was dropped. Under this system, 850 bar represented standard proof, with 1200 bar being special or magnum. 2 1/2" chambered guns are usually proofed 850 bar
2 3/4" chambered may be proofed 900 bar (3 1/4 tons per sq. inch) or higher.
**650 bars is standard CIP (British and European) service pressure for shells designed for guns proofed at the CIP standard of 850 bars**
European (CIP) proof pressure of 850 kg per sq. cm. (BAR) = 13,920 psi proof pressure= 10,730 psi service pressure (SAAMI)
Per the 1954 Rules of Proof, here are the equivalent service pressure values:
3 tons--8,938 psi
3 1/4 tons--9,682 psi
3 1/2 tons--10,427 psi
4 tons--11,917 psi
These numbers SHOULD apply to guns proved under the 1925 rules, which were stamped only with chamber length and shot charge. Thus, a 2 1/2" chambered gun, 1925 rules of proof, would be equivalent to 3 tons; a 2 3/4" chambered gun to 3 1/4 tons.
A service pressure of 3 tons per sq. in. = 8,938 psi service pressure (SAAMI)
For comparison, here's data from actual pressure testing:
3 Dr.Eq. 1 1/8 oz. Winchester Trap Load1,202 fps 9,600 psi
Winchester AA Xtra-Lite 1 oz WAAL12
1189 fps 8000 psi
Standard 1900s loads per LC Smith Hang Tags:
12g 3 dram 1 1/4 oz 1165 fps
16g 2 1/2 dram 1 oz 1165 fps
20g 2 1/4 dram 7/8 oz 1155 fps
The 12g 2 5/8" 1 1/8 oz. 3 1/4 Dram Eq (1295 fps) load of the 1920s ran about 10,500 psi.
The Super-X 2 3/4 inch 3 3/4 dram equiv. 1 1/4 ounce load (1330 fps) was near the SAAMI max. of 11,500 psi.
Baschieri & Pellagri data BUT you must add 500-1000 psi to the reported pressure to get an approximation of the SAAMI equivalent PSI. The 16g F2 Classic is factory listed at 9,867 psi but testing by Tom Armbrust showed it to be 10,500.
http://www.bandpusa.com/files/db_trio.pdf
Gamebore Traditional Game 16g 28gm (1 oz.) is reported to run 1260 fps at 8122 psi but pressure testing by Tom Armbrust showed it to be 8400 psi. The box is labeled "These cartridges are suitable for use in:
70mm case length: Guns with a chamber length of 2 3/4" or longer, nitro proofed to a service pressure of 3 1/4 tons per square inch (900 kg per square cm)
67 mm case length: Guns with a chamber length of 2 1/2" or longer, nitro proofed to a service pressure of 3 tons per square inch (850 kg per square cm.)"
It's appropriate to view the 3 ton/650 bar/8,939 psi pressure as the maximum service/using pressure rather than the standard/recomended service pressure. The Gamebore loads run below 8500 psi but are 'approved' for use in 3 ton/650 bar service/850 bar proof guns. In light of the age of the wood and metal of classic American and British SxSs, shoot low pressure to save the action, shoot light shot charge/low velocity to spare the wood. It seems reasonable to limit pressure to 8,500 psi, and several commercial loads are available from 5,000- 7,000 psi http://www.doublegunshop.com/forums/ubbt...ge=11#Post31805
BOTTOM LINE: ANY 850 BAR (proof) = 650 BAR service or 3 TON service gun should be fine at pressures under 8500 psi, or 3 1/4 tons less than 9,500 psi.
ANSI/SAAMI Shotgun Pressure Specifications (Maximum Average Pressure in PSI)
All Piezo measurements unless specified)
Cartridge Maximum Average pressure
10 gauge 11,000 (all)
12 gauge 11,5000 (all but 3 1/2" mag)
12 gauge 3 1/2" mag 14,000
16 gauge (11,500 (all)
20 Gauge 12,000 (all)
28 gauge 12,500 (all)
.410 Bore 2 1/2" 12,500
.410 Bore 3" 13,500
WEIGHT
1 ounce = 0.0625 pound= 28.35 grams
24 gm=.85 oz.=just less than 7/8 oz.
26gm=15/16 oz.
28 gm=1 oz.
30gm=1.06 oz.=1 1/16 oz.
32 gm=1.13 oz.=1 1/8 oz.
34 gm=1.2 oz.=1 1/5 oz.
36 gm=1.27 oz.=just more than 1 1/4 oz.
http://www.kentgamebore.com/gamebore_traditional.asp
There are three pressure measurement systems (lead crushers/LUP, copper crushers, and piezo), and two standard systems of measure units (USA/SAAMI and CIP/British/European) and two differing units (psi and tons and bar and Kg/Cm sq) within each system, different proof laws by country, and differing proof laws by age.
Unfortunately, there is essential NO formula to convert BAR expressed as LUP (CIP) to PSI (SAAMI). LUP + 1000 does not reliably predict the actual piezoelectric transducer measured pressure.
In 1989, all proof data was marked in metric using the BAR as the unit of measurement. The use of TONS per sq. inch was dropped. Under this system, 850 bar represented standard proof, with 1200 bar being special or magnum. 2 1/2" chambered guns are usually proofed 850 bar
2 3/4" chambered may be proofed 900 bar (3 1/4 tons per sq. inch) or higher.
**650 bars is standard CIP (British and European) service pressure for shells designed for guns proofed at the CIP standard of 850 bars**
European (CIP) proof pressure of 850 kg per sq. cm. (BAR) = 13,920 psi proof pressure= 10,730 psi service pressure (SAAMI)
Per the 1954 Rules of Proof, here are the equivalent service pressure values:
3 tons--8,938 psi
3 1/4 tons--9,682 psi
3 1/2 tons--10,427 psi
4 tons--11,917 psi
These numbers SHOULD apply to guns proved under the 1925 rules, which were stamped only with chamber length and shot charge. Thus, a 2 1/2" chambered gun, 1925 rules of proof, would be equivalent to 3 tons; a 2 3/4" chambered gun to 3 1/4 tons.
A service pressure of 3 tons per sq. in. = 8,938 psi service pressure (SAAMI)
For comparison, here's data from actual pressure testing:
3 Dr.Eq. 1 1/8 oz. Winchester Trap Load1,202 fps 9,600 psi
Winchester AA Xtra-Lite 1 oz WAAL12
1189 fps 8000 psi
Standard 1900s loads per LC Smith Hang Tags:
12g 3 dram 1 1/4 oz 1165 fps
16g 2 1/2 dram 1 oz 1165 fps
20g 2 1/4 dram 7/8 oz 1155 fps
The 12g 2 5/8" 1 1/8 oz. 3 1/4 Dram Eq (1295 fps) load of the 1920s ran about 10,500 psi.
The Super-X 2 3/4 inch 3 3/4 dram equiv. 1 1/4 ounce load (1330 fps) was near the SAAMI max. of 11,500 psi.
Baschieri & Pellagri data BUT you must add 500-1000 psi to the reported pressure to get an approximation of the SAAMI equivalent PSI. The 16g F2 Classic is factory listed at 9,867 psi but testing by Tom Armbrust showed it to be 10,500.
http://www.bandpusa.com/files/db_trio.pdf
Gamebore Traditional Game 16g 28gm (1 oz.) is reported to run 1260 fps at 8122 psi but pressure testing by Tom Armbrust showed it to be 8400 psi. The box is labeled "These cartridges are suitable for use in:
70mm case length: Guns with a chamber length of 2 3/4" or longer, nitro proofed to a service pressure of 3 1/4 tons per square inch (900 kg per square cm)
67 mm case length: Guns with a chamber length of 2 1/2" or longer, nitro proofed to a service pressure of 3 tons per square inch (850 kg per square cm.)"
It's appropriate to view the 3 ton/650 bar/8,939 psi pressure as the maximum service/using pressure rather than the standard/recomended service pressure. The Gamebore loads run below 8500 psi but are 'approved' for use in 3 ton/650 bar service/850 bar proof guns. In light of the age of the wood and metal of classic American and British SxSs, shoot low pressure to save the action, shoot light shot charge/low velocity to spare the wood. It seems reasonable to limit pressure to 8,500 psi, and several commercial loads are available from 5,000- 7,000 psi http://www.doublegunshop.com/forums/ubbt...ge=11#Post31805
BOTTOM LINE: ANY 850 BAR (proof) = 650 BAR service or 3 TON service gun should be fine at pressures under 8500 psi, or 3 1/4 tons less than 9,500 psi.
ANSI/SAAMI Shotgun Pressure Specifications (Maximum Average Pressure in PSI)
All Piezo measurements unless specified)
Cartridge Maximum Average pressure
10 gauge 11,000 (all)
12 gauge 11,5000 (all but 3 1/2" mag)
12 gauge 3 1/2" mag 14,000
16 gauge (11,500 (all)
20 Gauge 12,000 (all)
28 gauge 12,500 (all)
.410 Bore 2 1/2" 12,500
.410 Bore 3" 13,500
WEIGHT
1 ounce = 0.0625 pound= 28.35 grams
24 gm=.85 oz.=just less than 7/8 oz.
26gm=15/16 oz.
28 gm=1 oz.
30gm=1.06 oz.=1 1/16 oz.
32 gm=1.13 oz.=1 1/8 oz.
34 gm=1.2 oz.=1 1/5 oz.
36 gm=1.27 oz.=just more than 1 1/4 oz.
KICK *! THANKS!!!