 |  | | | |  | |  |  | Transfer Port Question |  | |  |  | |
 Posted: Wed Mar 14, 2012 9:41 am |
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| Houleigan |
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Ok I have a break barrel .22 rifle, but when I had it apart I noticed that the transfer port is only .177 (4.5mm) so my question is can the transfer port be enlarged to .22 (5.5mm)?
What would be the pros and cons of doing such a mod? |
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| Posted: Wed Mar 14, 2012 10:39 am |
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| rsterne |
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Actually, the transfer port is probably smaller than that, about 3mm is typical.... If you hog it out, you will likely end up with the piston crashing into the end of the chamber and ruining the gun.... It is restricted for a reason....
Bob |
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Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal: Too many to count! |
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| Posted: Wed Mar 14, 2012 10:40 am |
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| SMP |
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It will actually hurt the performance of the rifle.
There are two very famous texts by the Cardew Brothers. They did extensive testing and research on all things springer.
They found that the transfer port needed restriction so that the pressure in the tube would climb before the pellet started to move. If you enlarge the transfer port the pellet starts to move at much lower pressures which decreases the muzzle velocity.
It's a good idea to remove any sharp burrs in the port itself but other than that unless you are equipped with a full machine shop there is not much that should or can be done. |
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Sean
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| Posted: Wed Mar 14, 2012 11:00 am |
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| radar |
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| I can vouch for that. I bored one out and the velocity and the accuracy dropped. Most are sized about 1/8 inch or a little smaller for both .177 and .22, and that seems to be ideal. |
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It's never too late to have a happy childhood. |
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| Posted: Wed Mar 14, 2012 9:03 pm |
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| Houleigan |
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| Good to know, thanks everyone |
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| Posted: Fri Mar 16, 2012 9:52 pm |
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| robert w |
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| i think airgun world had a big article on opening up those ports DONT DO IT . but if done you can tap the hole and make a threaded bushing to reduce it back to stock size |
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,crosman 400,gamo big cat in .22, diana 5g,diana 54 air king, diana 34 in .22 diana 34 in .177, wilrauch hw-55,and a romainian pioner training rifle , and a huge collection of powder burners 35 last count . 1 would think i have a gun store |
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