Crosman hollow probe build

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    Would not the easiest way to line the hole be to make the bolt/probe minus the hole, then with the breach attached to the barrel, lock the bolt shut turn the breach and barrel upside down in a vice, aline it and with a drill press, drill it to just shy of actual circumference needed then finish it off out of breech. This to me would eliminate the need to have to work out angles, as the hole is drilled at the correct point for the locked position of the bolt.
 I love the tapered edge for end of probe. Assuming that pellet skirts are even and not causing a lockup against the barrel, I imagine that air/CO2 will after the initial push starting the pellet, push back causing the skirt to flare nicely with good pressure. Be keen to hear results when done. Looks like I might be ditching the extended probes I have which are awsome for your design if they work well. And of course if I can persuade you to make me a couple.

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kruzaroad Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 03 Jul 2022 Location: Hastings 4 now Status: Offline Posts: 2691	Post Options Post Reply Quote kruzaroad Report Post Thanks(0) Quote Reply Posted: 11 May 2023 at 5:07am
	Would not the easiest way to line the hole be to make the bolt/probe minus the hole, then with the breach attached to the barrel, lock the bolt shut turn the breach and barrel upside down in a vice, aline it and with a drill press, drill it to just shy of actual circumference needed then finish it off out of breech. This to me would eliminate the need to have to work out angles, as the hole is drilled at the correct point for the locked position of the bolt. I love the tapered edge for end of probe. Assuming that pellet skirts are even and not causing a lockup against the barrel, I imagine that air/CO2 will after the initial push starting the pellet, push back causing the skirt to flare nicely with good pressure. Be keen to hear results when done. Looks like I might be ditching the extended probes I have which are awsome for your design if they work well. And of course if I can persuade you to make me a couple.

nunga Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List Admin Joined: 09 Mar 2013 Location: Pukekohe Status: Offline Posts: 1083	Post Options Post Reply Quote nunga Report Post Thanks(0) Quote Reply Posted: 11 May 2023 at 4:57am
	I would be interested to see how much it cools down per shot due to the CO2 expanding at a faster rate. Looks good!
	2nd place HP springer - WFTF World Championships 2014

Billbobnz Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 14 Jun 2020 Location: Ashburton Status: Offline Posts: 918	Post Options Post Reply Quote Billbobnz Report Post Thanks(0) Quote Reply Posted: 11 May 2023 at 3:04am
	wow great work Paul, let use know if you get any increase of power when you test shooting it

Pauly5 Members Profile Send Private Message Find Members Posts Add to Buddy List Forum Moderator Joined: 11 Mar 2013 Location: Titahi Bay Status: Offline Posts: 1676	Post Options Post Reply Quote Pauly5 Report Post Thanks(0) Quote Reply Posted: 10 May 2023 at 4:11pm
	With new enthusiasm I started making a couple of new hollow probes. These allow the air or CO2 to travel up and act directly into the back of the pellet. The other design factors i've included are a tapered edge that fits inside the pellet skirt and enough length that it seats the pellet past the transfer port into the breech. I tapered the edge so that it should help engage the skirt with the rifling and so create a good seal. I will let the photos do the talking, but this is progress so far. First photo shows the main profile and O ring groove formed Here you can see the probe halfway across the TP, and second photo shows a clear passage through probe. The next couple are various angles of the hollowed out probe. I still need to workout the bolt hole angle and placement so that the hole lines up with the transfer port when pushed home. One more showing how the taper fits into the pellet skirt.