technical question
fellow airgunners, could you be so kind to explain me why it is that once you mill a barrel outside diameter down, the bore diameter will increase?? What’s the story behind this….. is there any way to prevent this from happening??
kind regards, vincent van gerven
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Viewing 6 replies - 1 through 6 (of 6 total)
Well, even if it does happen, as long as there isn’t anything wierd going on as you approach the barrel crown, it probably makes no significant difference in either accuracy or power.
Just my $.02
DaveK
This does actually happen. When you push a pellet down a airforce bore you feel it tighten after 6cm. It’s especially evident in .25 barrels as there is very little material to keep the bore stable. Most airgun barrels are button drawn. This introduces a lot of stress in the material around the bor but the rest of the barrel keeps it well in place. When you remove this material the stresse can rearange itself thus the bore swells. No big deal in my humble opinion but noticable. You can even see the place where the barrel goes from 8 to 16mm if you loop down the bore!
regards,
Marc
If this were true then you would think that all the Airfoce barrels would have a problem. Half the barrel would be loose and then it would tighten up the second half?
I would think you would see this in any kind of machining where you have a center hole and then you take some of the outer material away. I cant say that Ive seen that in my experiences.
Sounds like one for the MythBusters.
Hi
I can only think that it is due to the material stress releiving itself.
I haven’t got a clue how you would solve this.
How much does it expand by?
Viewing 6 replies - 1 through 6 (of 6 total)
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This is why fine target bbl’s are stress relieved after machining and straightening.
Mike