Steel Breeches
May 22 2005 at 10:18 PM Tom @ Buzzard Bluff
Response to That's a great idea....................
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Izzie wrote: <Got any more goodies laying around!>
How 'bout a steel breech for cheap? If you have lots of old parts guns laying about as I do then you probably have the steel replacement breech for that pistol you're spending your children's inheritance on as you replace original parts.
The 140 breech fits some things as is. (Crosman 150 for one)
But even if the bolt spacing is wrong it'e relatively easy to fill the front hole (the one under the nose of the bolt) and redrill it as needed.
Or you can pay someone $50 -$60 for one. Me? I'm 'the last of the bigtime cheapskates'.
BTW, I drill the nose of the 140 bolt (in the lathe) for a 1/16" music wire probe. Mix a small batch of JB Weld and after taping the nose of the bolt, to prevent the JB from running out the transfer port passage in the side, fill the nose of the bolt with the JB, insert your new (overlong) music wire probe and clamp it in the vice to dry overnight. If not left under pressure the wire tends to creep back out because as you insert it thru the JB it pushes a tiny column of air in front of it that can't bleed off thru the viscous JB Weld. I also roughen the portion of the music wire that fits into the bolt with very course sandpaper to give it some 'tooth' for the JB to grip. Prevents using it as a missile.
The next day stick the bolt back in the lathe and turn the original bolt nose, JB weld and all, in front of the O-ring groove to a nice taper that flows into the new music wire probe. This will reduce obstruction of flow between transfer port and pellet and give you a small incremental power increase.
Final step is to cut the probe to the proper length to seat the pellet just in front of the transfer port. It helps if you already know what pellets your barrel prefers since the depth of the hole in the pellets varies from brand to brand and even among different pellets in the makers line.
Avoid excess space between transfer port and the skirt of the pellet since a portion of your sweat equity air charge would be wasted by having to fill that space and, in extreme instances, you might even suffer a net loss of velocity. Conversely be very certain that the skirt is seated in front of the transfer port or all sorts of bad things happen when the skirt is subjected to the high-pressure flow when the valve opens. Deformed skirts just don't shoot straight. (or very fast either)
HTH, Tom @ Buzzard Bluff