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Crosman hollow probe build |
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Billbobnz 
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Joined: 14 Jun 2020 Location: Ashburton Status: Offline Posts: 918 |
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 Posted: 12 May 2023 at 2:50pm |
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Mate they are making me want to get a lathe.....
Hopefully getting one at work soon. So hopefully will finish a few projects around here. |
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RangerPete
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Joined: 19 Apr 2023 Location: Cambridge. Status: Offline Posts: 1035 |
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Posted: 12 May 2023 at 3:37pm |
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Hi Paul,
I don’t know much about pellets and probes, but would the beveled edge of the probe help in “reshaping” a damaged skirt as it seats it into the barrel? I’ve often wondered if shaping a pellet probe exactly as you have done would be able to gently “re-round” a bent skirt helping it to seal better, be more accurate etc etc… |
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Walk quietly, but carry a big stick.
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kruzaroad
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Joined: 03 Jul 2022 Location: Hastings 4 now Status: Online Posts: 2692 |
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Posted: 12 May 2023 at 3:55pm |
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Fear not billbob you can always use a drill and a file.
 You'll have ball if you get one at work,and you got the old fella up the road to give you some seriously good tips and tricks. |
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Pauly5
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Joined: 11 Mar 2013 Location: Titahi Bay Status: Offline Posts: 1676 |
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Posted: 12 May 2023 at 4:42pm |
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Pete, that was the thinking behind that, in the hope it would help do that and seat the pellet skirt onto the rifling.
Edited by Pauly5 - 12 May 2023 at 4:44pm |
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Pauly5
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Posted: 12 May 2023 at 4:44pm |
That is exciting.
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RangerPete
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Posted: 14 May 2023 at 8:27am |
👍🏻👍🏻👍🏻 would be interesting to do some simple tests and see if it works, once you have a working prototype 👍🏻 |
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Walk quietly, but carry a big stick.
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Pauly5
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Posted: 14 May 2023 at 2:51pm |
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It's been a good day in the workshop. Today I took the 362 apart to work on the valve area,
Drilled out TP in the barrel to 4 mm drilled out TP to 4 mm shaped the outlet valve in the valve body I started to slim the valve stem and broke it, so I ended up making a new one. I didn't thin out this stem, but round off the edges of the valve stem body for better flow around it, but only minimal difference. I also made a delrin spring seat which would increase the hammer spring tension. This sits inside the hammer. Photos to follow, and chrony results you will want to see at the end.   Spring ends on the hammer spring are horrific, so they got smoothed off.  New valve stem next to the broken factory one. Now I know I can successfully make them I might try slimming out the stem for better flow.  Delrin seat for hammer tension increase.  A couple of angles of the valve body. Trying to show the smoothed out angle for better air flow.   So what were the results? Prior to this work I had already fitted a hollow probe: Using 18 grn JSB 8 pumps I was getting 13.80 fpe. 12 pumps 16.11 fpe After the above works using 18 grn JSB 8 pumps - 15.71 fpe - 624 fps 10 pumps - 17.61 fpe - 661 fps I'm pretty impressed with that. I packed it in for the night, but will see if all the air has been dumped and will try 12 pumps tomorrow. Then accuracy needs to be tested.   |
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kruzaroad
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Joined: 03 Jul 2022 Location: Hastings 4 now Status: Online Posts: 2692 |
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Posted: 14 May 2023 at 3:01pm |
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Dude that's a nice jump up in fpe.
You must happy with the alterations. Great review throughly enjoying it Awsome detail photos. |
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Pauly5
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Posted: 14 May 2023 at 3:24pm |
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Glad you like it, It's been really enjoyable doing it.
I've been making drawings with measurements so I can make more bits later without having to take it apart and measure things again. It also helps me figure out the order of operations.
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RangerPete
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Posted: 14 May 2023 at 3:48pm |
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Very interesting thread.
And you are lucky to have the machinery, and the knowledge, to be able to tinker and create 😉 Have you tried a few damaged skirts on that beveled probe yet? I’ll bet it works a treat! 😉 |
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Walk quietly, but carry a big stick.
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Billbobnz
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Posted: 14 May 2023 at 4:02pm |
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That... Is awesome. Fantastic results.
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Pauly5
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Posted: 14 May 2023 at 4:26pm |
I will have a go at that next. I know the probe seats the pellet well as there are clear rifling marks on the skirt after pushing the bolt home.  |
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Pauly5
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Posted: 16 May 2023 at 1:46am |
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Quick update.
12 pumps = 19.16 fpe / 690 fps Bent pellet skirt testing to come.
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Myson
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Joined: 07 Mar 2016 Location: Feilding Status: Offline Posts: 226 |
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Posted: 16 May 2023 at 2:02am |
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Paul - you're an engineering genius!!!
I wish I had your skills!
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https://www.youtube.com/watch?v=eq7jVyBfFqE
Air Arms S510 US .22 Air Arms S410 .22 Weihrauch HW97KT .177 Weihrauch HW95 .177 |
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jwabfrog
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Joined: 13 Nov 2021 Location: Thames Status: Offline Posts: 159 |
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Posted: 16 May 2023 at 2:44am |
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Seriously impressive results, well done
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Billbobnz wrote: