Five Easy Probes

[Paul]

From Caliber to calcium, looking good, I'll watch this one.

[twigboy]

Yes! The answer is in the slot, not the bolt...but sealing might be more difficult, or require a different leade design/size] 

Put the o-ring (or 2) in the receiver?     Slightly taper the bolt so that it glides through without catching the o-ring(s)

[Rualert]

   Yes Craig, I like that idea, and I mis-spoke on the placement of the o-ring, back of the barrel cut an o-ring groove, like the M-Rod, and a few others. This allows the bolt to push the pellet into the barrel, past the transfer port, pulled back then locked. I think we may have collectively stumbled on a potential design. The taller breech would be easier to implement, but a standard design type with the top slot log enough to push the pellet into the chamber, pull back, then lock down rather than the lock down at the front. This may very well work, see we are all smarter together.   

Casey

P.S. Yes Carl, that design of the taller breech gives the room for the J type slot, and I'm sure you read Bob's post where he added a small SHCS to limit the reward travel of the bolt after lowering it into the j slot to adjust how much of the TP is covered to adjust the amount of air getting to the back of the pellet or slug.

[Rualert]

    OK, had to throw in one more idea here, this might be better in the machining section if so please move there. Now to the point, someone mentioned a chamber behind the pellet for the charge/air expansion. This got me thinking about the TAU Junior I repaired for the state 4-H club. Their design is based around a bulk fill but also uses 12 gram carts. The cart is inserted in the grip tip down rather than up, and the cap pierces it and allows the gas to fill the space around the cart, and another space above it where their valve is located. Kinda hard to explain without pictures, but anyway the valve allows the gas to then flow into an expansion chamber just below the breech area. Pellets load directly into the barrel by hand (no probe or bolt), when the hammer opens the valve the gas fills that expansion chamber and is directed to the back of the pellet. I'll see if I can fin a decent picture. Collectively we might be able to design a breech that could be used with say a Pro Top that mimic's the expansion chamber design and only uses the bolt to seal the chamber so the gas gets directly to the back of the loaded pellet. OK, off to find a decent picture of their design so the group can ponder and think about the potential of such a breech / bolt design to implement such a design.

Casey
Wow crazy what one can think up once we have a grasp on Crosman's design and other's designs and trying to come up with a hybrid.

Found the exploded diagram of the Tau, might help show what I was trying to describe:


screenshot software

[CraigH]

Casey,

Years and years ago (squared) this is kind of the way I though the various Crosman CO2 air guns worked; i.e., the air tube was pressurized and pressing the trigger shot the gas from another valve-controlled chamber through the bolt.

[quickster47 †]

Casey, wow a TAU.  Can't believe that.  I've had one of those for 15 years and still have it and still shoot it.  Awesome, accurate gun for sure.

Carl

Okay, way off track, sort of.  But now we return control to the real thread. 

[Flattitude]

Wow beautiful gun.

[Rualert]

     They are very nice, I maintain most if not all of the air guns for the state 4-H program when they have more than simple issues. But as you said back to the point, if we were to add the o-ring to the end of the breech to seal the probe, then the solid or tubular probe could be a little simpler, along with the option of a pull back slot or second drop down slot to use after seating the pellet.

Just thinking out  loud again,

Casey

[mudduck48]

You had better watch that thinking out loud, you know that gets you in trouble.

[quickster47 †]

     They are very nice, I maintain most if not all of the air guns for the state 4-H program when they have more than simple issues. But as you said back to the point, if we were to add the o-ring to the end of the breech to seal the probe, then the solid or tubular probe could be a little simpler, along with the option of a pull back slot or second drop down slot to use after seating the pellet.

Just thinking out  loud again,

Casey

And I keep thinking and thinking about this probeless bolt.  Going over all kinds of ideas in my head and making notes and sketches.

One of these days, one of these days...

Carl

[mudduck48]

Probeless bolt?

[quickster47 †]

Close but no cigar.  That bolt still has a large appendage that blocks the transfer port, even if it is a flow through bolt.

Carl

[Poorman Plinker]

  I think Rualert has a good point. (Not being a machinest I will never build one) I agree that if the o-ring is not on the probe there IS more room/flexability for building a retractable bolt .
Apart from that, I have observed: In a hand loaded gun you need only press the pellet a bit deeper to make an expansion chamber.
My rhetorical/theoretical question is: Is it the expansion of the gas that caused the increased velocity or is it the gas hitting the full face (skirt) of the pellets?
Pressing a pellet a bit deeper into a Single Stroke pneumatic and doing some Chronograph tests might shed some light on the subject. Maybe using a TAU?
Carl, this post is going to go down as a classic in the pellet gun hall of fame and I reference it frequently. Thanks for doing the research.

[quickster47 †]

I am currently working on an extended tip probe that has an adjustable extension.

Pictures later and maybe some test data when I get a few things off my plate.

And even though I'm retired there still is not enough hours in the day.    

Carl

[Poorman Plinker]

Here's one to ponder on while I make a trip to the dentist this morning.

Carl

Missed this before commenting... Stroke of genius Carl! So simple to just have the bolt lug allow the bolt to retract. That should work perfectly regardless of pellet design and requires no complicated mechanisms. O-ring or seal in the breech trapped between the breech and barrel face? "The Quickster Probe-less Breech" - fits any standard 22xx Crosman receiver and barrel.