Factory 20 gauge pressures ?

[chris dawe]

Guys I recently came across a post on another forum demonstrating how to make short chambered shells out of factory loads ,using an appropriate sized diamond hole saw to cut out the factory crimp and replacing it with an overshot card ...sure makes access to short shells easy in place like where I live -where everything has to be brought in by boat or plane.

My question is that I know I seen mention of particular factory 20 gauge load pressures somewhere but just cant find it ...I know some of this factory stuff can run a little hot ,my bigger lefever 12 gauges and 2 frame Parkers offer no concern -but I shoot some little 20 bore guns that I would hate to stress

[Kensal Rise]

Chris:
This testing is for 12 bore. But empirical results appear to go for small bores too:


"Long Shells in Short Chambers”, Sherman Bell with technical assistance from Tom Armbrust in “Finding Out for Myself” Part V, Double Gun Journal, Winter 2001

The test barrel was a ‘heavy’ Krieger barrel with piezo-electric transducer at 1” from the breech and an Oehler velocity gauge 2 5/16” from the breech.
Tests were performed:
1. 2 1/2” chamber with a 7/16” forcing cone – “British chamber” (BC)
2. 2 1/2” chamber with a 1 1/4” forcing cone – “Modified British chamber” (MBC)
3. 2 3/4” chamber with a 1” forcing cone – “American Chamber” (AC)
Each load was tested in each chamber at least 5 times.
No significant change in velocity was noted between the 3 test chambers
It was not unusual to have 300-600 psi spread between shots

LOADS
1. 7/8 oz. in Federal plastic hull at 1185 fps in the 2 3/4” chamber
2. 7/8 oz. in Estate plastic hull at 1206 fps
3. 1 oz. in Federal paper hull at 1137 fps
4. 1 1/8 oz. in Federal paper hull at 1120 fps
5. 1 oz. in Remington plastic hull at 1205 fps
6. 1 1/8 oz. in Winchester plastic hull at 1186 fps
7. 1 1/4 oz. in Federal plastic hull at 1091 fps
8. 1 1/4 oz. in Winchester plastic hull at 1136 fps
9. 1 1/8 oz. with GOEX FFFg in Federal paper at 1184 fps
10. 1 1/8 oz. Bismuth in Federal plastic at 1091 fps
I only include the standard target or game loads that were tested

……..BC……...MBC…....AC…..Difference BCvsAC
1…..5725…….5905…..4834……891 psi
2…..6225…….6065…..5009……1216 psi
3…..5865…….5325…..5263……602 psi…..“long cones do reduce pressure”
4…..5845…….5665…..5058……787 psi
5…..7805…….7845…..7577……228 psi
6…..11,125….11,045…10,787….338 psi
7…..6892…….6805…..5953……939 psi
8…..8765…….8545…..7870……895 psi
9…..5405…….5265…..4603……802 psi
10…6765…….6365…..6380……385 psi

Interpretation and caution:
1. Results in light British 12b or American small bore barrels may be different.
2. Results in YOUR barrel would require drilling the chamber for the transducer thereby destroying your gun.
3. Paper hulls with star crimps showed little difference compared to plastic hulls. NO roll crimp paper hulls were tested.
4. The increase in pressure comparing 1 oz., 1 1/8 oz., and 1 1/4 oz. loads was similar.
5. Longer cones MAY reduce pressure. This was NOT a comparison of standard 1” with 2 1/2” cones however.
6. “Shooting 2 3/4” shells in 2 1/2” chambers does make them produce more pressure-but in most cases it is less than a 1000 psi increase. I see no reason, related to safety, to modify an original 2 1/2” chambered gun to shoot 2 3/4” shells, if the 2 3/4” load you intend to use would develop pressure that is safe in that gun, when fired in a standard chamber!”
7. “We found that lengthening the forcing cone in a 2 1/2” chamber usually helps mitigate the pressure increase that comes from shooting 2 3/4” or 3” shells in the short chamber.”
8. “Shooting heavy 2 3/4” loads in a light gun is a dumb thing to do. Shooting 3” magnum duck loads is even dumber.”

[Researcher]

SAAMI Specs.jpg

[Harold Pickens]

Chris, I load 2 1/2" 20's for my damascus J Manton hammer gun. That is the only gun I load 2 1/2" for--and generally 3/4 oz loads. I have a few load recipies at home, currently using Unique--I can find them if you like. There is a gent on the 16 Ga Forum that sell a little tool that fits in your drill, and you can zip 100 2 3/4" shells down to 2 1/2" in 5 minutes--works in 12-16-20 shells--costs around 20 bucks. The short kit I bought for my Mec 600 16 ga loader fits fine on my 12 and 20 loader also. As per the posts above, I wouldnt even bother with short 20's in fluid steel gun, but you'll love the 3/4 oz load.

[C.O.B.]

Chris can you import shells from say RST? I have found a manufacturer called Clever that produces a very nice shell and haver used them in 12 and 20. I know the 12's won't hurt a solid Damascus barreled gun but have no pressure results from the 20's. I load a low pressure 20 and these are very close to mine going by felt recoil or lack thereof and the published velocity of 1150 to 1200 FPS.

[chris dawe]

Thanks guys ,i am set up to reload ,and i also sell gamebore shells through my shop...but the prices of everything still makes large volume shooting cost prohibitive ..I seen this method and realized it could make a day at the trap club economical for my boy and his little LC.Smith ...I pay 40 + bucks for 100 rounds of Winchester or Federal promo loads up here .

[C.O.B.]

what length shell are you loading? I'm set up for all 2.5 inch and use the RST hull. If you need hulls I'm sure some could be sent your way.

[Buddy Marson]

[



This load was published in the LYMAN Shotshell Handbook 2nd Edition:
Hull= Winchester AA 23/4", Shot=7/8oz.,Power=GreenDot 14.5 grs., Primer=CCI 209,Wads=Winchester WAA20,
Velocity= 1150 fps, Pressure (L.U.P.)= 8,960.
I have been using this load for years and find it to be a very good and effective load.

QUOTE=chris dawe;240403]Guys I recently came across a post on another forum demonstrating how to make short chambered shells out of factory loads ,using an appropriate sized diamond hole saw to cut out the factory crimp and replacing it with an overshot card ...sure makes access to short shells easy in place like where I live -where everything has to be brought in by boat or plane.

My question is that I know I seen mention of particular factory 20 gauge load pressures somewhere but just cant find it ...I know some of this factory stuff can run a little hot ,my bigger lefever 12 gauges and 2 frame Parkers offer no concern -but I shoot some little 20 bore guns that I would hate to stress[/QUOTE]

[Harold Pickens]

Buddy, that same load recipie makes a really sweet little 3/4 oz load. Just sub a claybuster green 3/4 oz wad for the WAA 20