GTA
General Discussion To Gateway To Airguns => The Shop => : 1shotwander May 30, 2009, 04:09:22 AM
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Well to start things off, I was getting good groups with my BC, but I got a little greedy and decided to cut the factory crown off to see if I could get even BETTER groups, which was a mistake. Well I decided that since I more or less screwed myself with the groups , that I might as well start cutting the barrel down some more and to do some accuracy testing for some other people, so that way they don't make the same mistake as me. I had cut my barrel down from 18 inches to 16.5 inches... re-crowned, did the q-tip test and everything, but that was a while back. Just recently (about 2 weeks) ago I decided to cut some more off and record the data that I would get.
In this test I would test 3 different kinds of pellets.... well they were all CPHP's but one was cleaned, one was cleaned & furniture polished, and the other was regular straight out of the can pellets. I cleaned the barrel before the testing very good, I wiped it down, thenwiped some Goo-Gone in the barrel, waited about 5 minutes then I put a clean patch in.. I did that about 3 or 4 times, until no lead residue came out anymore. I also shot the cleaned first followed by the cleaned & polished followed by the regular cphp's. Then I cleaned out the barrel again. I then proceeded to cut the barrel, then re-crown and clean the barrel again. I cut my barrel from 16.5 inches to a little under 15 inches, trying to cut in half increments, though that didn't work that well. I think that I did a pretty good job on the results, though the one thing that could have been better would have been for me to have a crono to also get fps results..
Pictures are coming up soon.
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(http://i473.photobucket.com/albums/rr99/hexershoot/Airgun%20stuff/DSC00940.jpg)
15 inch: cleaned pellets
(http://i473.photobucket.com/albums/rr99/hexershoot/Airgun%20stuff/DSC00939.jpg)
15 inch: regular pellets
(http://i473.photobucket.com/albums/rr99/hexershoot/Airgun%20stuff/DSC00941.jpg)
15 inch: cleaned & polished pellets
(http://i473.photobucket.com/albums/rr99/hexershoot/Airgun%20stuff/DSC00949.jpg)
15.75 inch: cleaned and polished
(http://i473.photobucket.com/albums/rr99/hexershoot/Airgun%20stuff/DSC00950.jpg)
15.75 inch: cleaned
(http://i473.photobucket.com/albums/rr99/hexershoot/Airgun%20stuff/DSC00951.jpg)
15.75 inch: regular
(http://i473.photobucket.com/albums/rr99/hexershoot/Airgun%20stuff/DSC00942.jpg)
16.5 inch: cleaned
(http://i473.photobucket.com/albums/rr99/hexershoot/Airgun%20stuff/DSC00943.jpg)
16.5 inch: regular
(http://i473.photobucket.com/albums/rr99/hexershoot/Airgun%20stuff/DSC00944.jpg)
16.5 inch: cleaned & polished
(http://i473.photobucket.com/albums/rr99/hexershoot/Airgun%20stuff/DSC00945.jpg)
16.5 inch: cleaned
(http://i473.photobucket.com/albums/rr99/hexershoot/Airgun%20stuff/DSC00947.jpg)
16.5 inch: cleaned & polished
(http://i473.photobucket.com/albums/rr99/hexershoot/Airgun%20stuff/DSC00948.jpg)
16.5 inch: regular
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That's very interesting Cody,
What conclusions did you draw from this ?
Your 16.5" barrel looks like it had the best groups, but that 15" groups look very good also.
As for the cleaning and polishing, it looks like a draw between the cleaning and the polishing at different barrel lengths ? But in every case it looks like the uncleaned pellets had the poorer groups.
Do you see it the same way ??
Bill
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Big_Bill - 5/30/2009 3:20 PM
That's very interesting Cody,
What conclusions did you draw from this ?
Your 16.5" barrel looks like it had the best groups, but that 15" groups look very good also.
As for the cleaning and polishing, it looks like a draw between the cleaning and the polishing at different barrel lengths ? But in every case it looks like the uncleaned pellets had the poorer groups.
Do you see it the same way ??
Bill
Yup that's the same conclusion that I came up with. I couldn't belive how dirty those uncleaned pellets were. I doubt that my down accuracy will even exist anymore, but hell it was only $140 airgun, nothing major.
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cody how did you cut it ? it looks like you used a hacksaw from the pics and a little crooked? if you can find some one with a lathe that can swallow the breech block an tru it up like that that would be best . if not checking and rechecking with a good square from all directions to get it perfect will get you the best results . otherwise send it to me and i'll do it for you you just pay shipping .
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joeblow - 5/31/2009 10:27 AM cody how did you cut it ? it looks like you used a hacksaw from the pics and a little crooked? if you can find some one with a lathe that can swallow the breech block an tru it up like that that would be best . if not checking and rechecking with a good square from all directions to get it perfect will get you the best results . otherwise send it to me and i'll do it for you you just pay shipping .
Yup I did, I used a hacksaw, and the picture I should have never put up even, because I had to recut it again to make it square. I was using a square by the way.
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ahhh i see. well hopfully you get her dialed in i cut a few barrels down they all seemed to get the best right around 14 in. if that helps.
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A quick question.
How did you clean the pellets?
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fisherdude - 6/1/2009 9:00 PM A quick question. How did you clean the pellets?
I knew someone was gona ask about that..... Very carefully(http://../jscripts/tiny_mce/plugins/emotions/images/smiley-laughing.gif).... But all jokes aside, I cleaned them pain statingly the hard way... one by one on an old sock,,, want to talk about taking a long time
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(?) with my Big cat -The first shot is always high 5-7" inchs ,Then like it settles down an will do a good group 1 1/2 "
that with croseman hollows/ or Hunters. it likes a heave pellet. all from Bench rest.
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I have cut down a few barrels but they were all steel barrels I'm not sure how a BC ( polyester with a rifled liner ) would work since I'm not sure it has enough steel to crown it correctly. But5 you might try to get a barrel from Crosman since their rifles are clones of the gamo 220 ( china B19) and we are talking about 20 bucks approx you might be able to save your BC and end up with a all steel barrel. Maybe onw of the other members will chime in and give their thoughts if this will work maybe one of them have done this . Howie