If you have a 22 or 5.5mm barrel is that measured from the top of the rifling bottom of rifling? Are pellets naturally made larger than 5.5mm so they will engage the rifling?
Registered User
If you have a 22 or 5.5mm barrel is that measured from the top of the rifling bottom of rifling? Are pellets naturally made larger than 5.5mm so they will engage the rifling?
Registered User
They are usually measured between the lands and grooves of the rifling opposite of each other.
If you are already aiming for the exact center of everything, then the target’s size shouldn’t matter — the center of a beach ball is just as big as the center of an aspirin tablet. -Byron Ferguson
It's the hole down t'middle in effect. On powder burners or service rifles going back for ever the wear on the tube and consequent accuracy was monitored by the use of bore gauges which attach to rods as per;
https://cdn.globalauctionplatform.co...7/original.jpg
So the bore size is the size of an object that will pass down the barrel with a slight drag fit, ie. as near as dammit the same size. If an equal number of grooves then an expanding bore gauge can be used, if unequal then the old fashioned way is to ''slug'' the tube.
That's why pellets are sized by head size as the skirt is expanded to bigger than nominal bore size into the base of the grooves, easy to check if you measure an undamaged expended pellet.
ATB, Ed
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