Pedersoli Sharps Factory "O" Rings

[Wayne Clark]

Anybody have any experience with Pedersoli's Sharps 3 concentric "O" ring gas check system?
W. Clark

[Charlie Hahn]

Hi Wayne,

Are you referring to the three wave washers behind the gas check plate? If this is the "o-ring" design you are speaking about, I have worked with two
variations of these. One the gas check plate has a 3/8 inch hole, the other 9/16. Both have straight sides on the hole and let enough gas and fowling
in to lock the plate against the breech in about three shots. The wave washers are hardly stiff enough to hold the plate forward when clean. If you look at the pressures of the expanding gases, rubber o-ring, or wave washers are compressed until the gas check plate is against the breech block. I find
both poor designs. At least with the original design, the cone in the gas check provides a greater surface area for the gases to push back on the plate,however all of the Sharps Paper guns, Old and new have this issue. Either they have enough clearance to allow the dirt not to jam things up, or the clearance between the breech and the barrel end let gases flow to the extent is catches your shirt sleeve on fire, or blows your hat off. Not to mention the dirt in your face.

Charlie Hahn

[Wayne Clark]

Charlie,
The carbine I saw actually has 3 "O" rings that fit inside each other and fit behind the gas check in the breech block. It also has a removabable vent in the breech block and a small "T" handle wrench was supplied with the carbine. Must be new?
W. Clark

[bplvr]

I had pioneered the "O" ring idea 6 years ago. I ground the back of the gas check plate and inserted 3 concentric "star","quad" or "X" O-rings .062 'square'.
The plate is held against the chamber tube under pressure when the B/block is assembled. This is a real advantage when reenacting as I get 100+ shots
before the block starts to get clogged. My 'O' rings {first set} have seen 1000+ shots are still fine.
I also drilled a .062 hole in the nipple on the muzzle side to let fresh air chase the primer blast. This cut way down on FTF's .

- bplvr ,1st USSS "C" - Berdans {So.California}

http://www.marcorubber.com/quad_rings.htm

[Space Cowboy]

Hello Wayne,

The 3 O ring blocks are new on the market. This modification was launched for the "economy" cheaper rifles this year. they are intended to shoot with brass cartridges. They work with paper cartridges as well, but it fouls the action in 8-10 shots according to my tests. I have been experiencing with this new version for two monthes now. Here are some points:

- the O rings will burn quickly. I think it is better to change them after every shooting.
- the rifle likes clean burning, hot powdrs like the Swiss 3Fg. I does not work correctly with lower quality powders.
- make sure that you have the powder in the back of the cartridge, close to the touch hole, or you will have ignition problems.
- enlarge the touch hole of the brass to 2,5 mm to have good fast ignition
- the brasses are matching the reciever so perfectly, that after they deform a bit, they will be hard to remove from the frame. The easy solution for this is to round the bottom edge of the cartridge.
- 4 wing musket caps will do the job, but 6 wing is better for every percussion sharps
- the 54 cal DP gun likes the .541 Original Style bullets. They are very accurate with 55 gr 3Fg Swiss up to 100 m.

I recommend every shooter to use the gun with bras cartridges. With it it is easy to shoot 30-50 shots a day withou jamming action.

Best regards,
SC

[Dominic Infante, 8359V]

bplvr:

A crucial measurement for your breech block modification is the thickness of the breech block once the O-rings are installed. For instance, my breech block measures .875. What should it be once the O-rings are in place? This would suggest what compression is needed to press the gas check plate against the end of the chamber sleeve. I would imagine the number of thousanths would be the same if the compression if from the direction of the chamber sleeve, i.e., the chamber sleeve O-ring modification which is now quite popular.

Also, please explain what you mean by "star" and "X" O-rings. Does that pertain to brand name, shape, materials, ? Also, what is ".062 square"?

Thanks,