Very good idea on plugging the rubber plunger! I’ll be giving that a try. On the magnet placement, you are very similar to one of the tries I did. I’ve used the stock magnet in 2 locations. First was as close to the shot tube seat as possible. The second was centered on the lag diameter that you drill through, so it was further away from the bb. The one with the magnet closer to the seat had a bit higher mv. Then I got the 3/16” dia x 3/16” long magnets and drilled through just centered on the flat area. I pushed one in flush to the bore of the abutment. Better mv. Then put another on top so a combined 3/16”x 3/8” n52. About 4# pull. That was the best result for me. The hole is reamed at 0.1685”. Pushed in a countersink yo make a bit more funnel shape to “minimize” turbulence as the air is displaced. Soooo, don’t know how to know if this all allows some small amount of compression to build up before the bb breaks the magnetic field, but I think it does. Glad you are pursuing this project!Had a better day today. The big brown Daisy truck showed up with box of parts so everything else was put on hold. Came up with a simple way to plug the hole in the 105's piston. Used a #10 x 32 nylon screw. Drilled the hole out to 11/64" down to where the retainer pin goes in. Then cut the screw to the proper length and using a band saw made a slot in the end of the screw for a screw driver. Seems to work well and the screw also holds the pin in place so there is no chance of it touching the cylinder wall.
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Made a shorter preload space as I wanted to add a washer between the spring and spacer. It's my understanding that coil springs like to twist during compression and the smoother they can do this the less they get distorted. Then the abutment was modified by moving the magnet to the side and the air port opened up. As I understand it hinz used a stronger magnet to let compression build before the BB starts down the shot tube. I tried the opposite as an experiment. Using the stock magnet the abutment was machined so that the BB doesn't quite touch the magnet. The idea being the BB can start picking up speed as soon as possible and the BB is held tight against the air passage to seal it. I don't know if it is better but the velocity is now running in the 450's and you can still hear it click when it gets to the abutment. Enlarge the photo and you can see what this is about.
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Looks good! For me, this all takes multiple tries! What material did you make your extension from?Spent this afternoon working on the 499 again. Made a rubber snubber to fit half way down the barrel and the air tube. But didn't see any improvement in the velocity.
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Then decided to go ahead and extend the barrel to support the extra air tube. Took an old abutment and made it into the cap for the barrel. Threaded the end of the air tube for it to screw onto. Turned down the end of the plastic funnel for the other end of the barrel extension to slide onto.
View attachment 838691 Assembled it and ran into a problem. Now the abutment is turning in the gun and I can't get the original barrel out. But the gun was assembled so I ran it over the chrony. What happened was beyond anything I was expecting. Below was the first shot.
View attachment 838695 The next photo was the third shot and the rest were in between these two. So Vibration in the extension does have a bearing on velocity.
View attachment 838696 Was hoping to post some photos of nice groupings but ran into another issue. The plastic funnel is only held centered in the barrel by four little (very little) plastic ribs.
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Once these get abused a little bit they flatten out and the barrel start floating around. My first groups were pretty good but then started spreading out. I thought maybe the extension was coming loose but it wasn't. Did notice a lot of play and it was coming from between the barrel and the funnel. So that is going to have to be dealt with before and more groups are shot. That's where things stand as of today.
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Now your going to make me admit I messed up. I had intended to use a piece from another barrel. Cut the piece in the chop saw and all was good. Placed it in the lathe to square things up and the tube having a split seam didn't agree to this. Planned on making a very light cut but it still caught on the seam and ruined the barrel.What material did you make your extension from?
Thanks. I’m guessing you had the tube in a 3 jaw? I will be trying the same process using collets. I’ve thought about making a split block with 2 holes that would clamp a barrel shroud with the small tube underneath to be able to mill the ends square. Or to hold it square to a disk sander. It should also work with the barrel tube only. I’ve considered several ideas for barrel shroud extension but haven’t settled on anything yet.Now your going to make me admit I messed up. I had intended to use a piece from another barrel. Cut the piece in the chop saw and all was good. Placed it in the lathe to square things up and the tube having a split seam didn't agree to this. Planned on making a very light cut but it still caught on the seam and ruined the barrel.
Having flown and worked on Ultralight aircraft I had some aluminum tube that was the same OD. It's 6061 and is nice to work with so that's what the extension is made of. If you need some let me know.
Glad your feeling better. Have missed your posting here.
I’ve also considered the 2 magnet option but haven’t tried it. I have some thought that perhaps having the magnet oriented to the bottom is part of daisy engineering to put a bit of spin on the bb “hopup”, or “hopdown”. I will at some point do an abutment with the magnet at the top, which is how, if I understand correctly, that hopup is normally done. This is all conjecture on my part.When the gun is apart again I'm going to try another magnet 180 degs from the first one just to see what two magnets will do. Trying to keep the BB centered in the abutment port.
Just a heads up. My abutment has started turning in the cylinder so the barrel can't be unscrewed. Going to have to stake it somehow so that it can still be easily removed. Maybe a set screw.
Just a though to hold the abutment enough to unscrew the tube. Maybe make a long tool to drive in the abutment from the air chamber side to hold it from turning. Perhaps a torx bit or a screwdriver. Would leave a bit of a mark, but that could be dealt with after a successful abutmentectomy!When the gun is apart again I'm going to try another magnet 180 degs from the first one just to see what two magnets will do. Trying to keep the BB centered in the abutment port.
Just a heads up. My abutment has started turning in the cylinder so the barrel can't be unscrewed. Going to have to stake it somehow so that it can still be easily removed. Maybe a set screw.
Well, mine, in the pix is backward also. I have to pay more attention to that! Thx!I've been fortunate that the abutments in my guns have stayed put. I don't tighten the shot tube very tight so it's relatively easy to remove and the threads are lubed to help with that.
Guys, what is the blind hole in the abutment for, anyway? (Photo shows the seal on backwards- I had 2 come from Daisy like that. Almost installed it that way, too.)
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These last entries are priceless. I'll figure something out. Might take some careful measurement and drill through from the outside and install a set screw. Gotta be careful as I don't want to put any scratches in Mark's gun.abutmentectomy!
That's impressive considering the subject matter.People, this thread just exceeded 100.000 views! It is averaging right at 100 views a day.
Maybe, before you drill a hole, make sure of abutment magnet orientation. I have some gut level feeling that it makes a difference. Maybe drill the staking locations. It would be hidden and the is a ready made center punch hole. Then the set screw could seat in the abutment staking slot(recess).These last entries are priceless. I'll figure something out. Might take some careful measurement and drill through from the outside and install a set screw. Gotta be careful as I don't want to put any scratches in Mark's gun.
I've wonder about that little hole in the abutment also.
A parachute type seal definitely works better with the lip facing the pressure.
That's impressive considering the subject matter.
I had only looked at amazon. Are you satisfied with image quality? Do you use it with a phone? iPhone or android? Thx!I got a 'scope from a Chinese importer named "Banggood". Not kidding. Their grasp of English is priceless. Anyway, it's 5.5 mm at the lens/led end, 1 m long, illuminated with 6 LEDs and pretty much self contained. Cost me all of $11.00 delivered. Likely there are other importers offering much the same thing.
I'd be happy to send it to you but by the time we mailed it to and from, we'd have spent enough to buy one!
https://www.banggood.com/search/endoscope.html