what's costing pellet to spiral with 2 different barrel on the same gun?

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Jack.K

Jack.K

Member
Oct 12, 2015
890
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San Francisco , California
Just got my Impact from the shop for a air leak. The Leak was find at the air transfer tube. The gun got rebuild with new cocking block, valve, steel probe block and set screw and new Power wheel. After chrono testing and mounted the scope and sight in the gun at 23 yards with JSB 15.9g at 937 pfs. I went to shoot at my target which was at 88 yards and the pellet was going all over the place so I ask myself what's going on? I install my scope cam and I saw pellet spiraling once it goes passed 30 years or so. I checked the pellet before loading them without the magazine, remove the shroud and still doing the same. Remove the shroud and push the pellet through the barrel with a Hershey's marshmallow stick (yes Marshmallow stick) and inspected the pellet for damage and didn't see anything. I decided to install my .25 barrel with JSB 33.9g at 740fps and give it a go and I got the same problem. I didn't have problem shooting at that speed and at the same target before. Their almost no wind when shoot the video. What could be wrong?

Marshmallow stick


Impact .22 with JSB 15.9g

Impact .25 with JSB 33.9g



 
Good troubleshooting thus far.

Did i read correctly that you already tried hand loading the pellet? I've read that some magazines actually damage the pellet.

I think 937 fps is too fast for the .22 pellet/barrel combo. Stick to 900 or less.

Strange that the .25 shooting slow yields same results.

2 more things to check:
1. Inspect your pellet probe.
2. Inspect the Smooth Twist portion of the barrel (just the last few inches before the muzzle).
 
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I load the pellet by removing the barrel from the gun and push the pellet in with small wooden dowel to rule out the pellet probe problem. I inspected the Smooth Twist portion of the barrel and didn't find any issue that I can see. Still have the same problem. The .25 barrel was not sent out with the gun for service so why the spiraling is with that barrel too. I had no problem shooting at 920 - 940 fps with the 15.9g pellet before. Here are couple of videos of the pellet in flight with a 85 yards "target" shooting at 930 fps using that same tin of pellets.

edited to clarify that these video are before I had the air leak problem and pellet didn't have any sprial on them.


follow up shoot.
 
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"KenSkylight"1. Maybe your gun uses more air than needed because the valve is too long open,play with the power wheel! 
2. maybe there was cross winds and all is fine?
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cross winds do make the pellets spiral, I have seen the same from my Wildcat and Vulcan in cross winds at a longer distance. However I hunted with both at distances as 115, 125 and 130 yards without any issues.
 
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I'm having the same spiraling problem. So frustrating. I could write a list of all the things I've tried but then I would just get responses telling me to do the same things I've already tried. If I sent the gun in a couple times already and now I'm too frustrated and tired of trying to figure it out. Eventually I'll just send it back to have it worked on and hope it comes back shooting straight. Mine is fairly accurate out to 30 yards but the poi will shift. At long distance it always spirals no matter what I do. In your situation you had a straight shooting barrel at one point but then it changed/spiraled after the leak got fixed. So something had to of happened during the rebuild. Just a shot in the dark...maybe there's oil that is getting into the system that ends up leaving residue in the barrel after each shot?...
 
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"SethAZ"I'm having the same spiraling problem. So frustrating. I could write a list of all the things I've tried but then I would just get responses telling me to do the same things I've already tried. If I sent the gun in a couple times already and now I'm too frustrated and tired of trying to figure it out. Eventually I'll just send it back to have it worked on and hope it comes back shooting straight. Mine is fairly accurate out to 30 yards but the poi will shift. At long distance it always spirals no matter what I do. In your situation you had a straight shooting barrel at one point but then it changed/spiraled after the leak got fixed. So something had to of happened during the rebuild. Just a shot in the dark...maybe there's oil that is getting into the system that ends up leaving residue in the barrel after each shot?...


Click to expand...
I will try to run more patch through the barrel and see if that will help. Now only if I have a swimming pool and shoot some pellets in the pool and recover them and compare them to the one I pushed out will the marshmallow stick.
 
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