Reply To: Vulcan 25 cal VS Wildcat 25 cal

Forums PCP Airguns Vulcan 25 cal VS Wildcat 25 cal Reply To: Vulcan 25 cal VS Wildcat 25 cal

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zebra
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“fe7565”Read somewhere that horizontal groups (besides the wind) may be from the expansion/contraction of the air tank as it affects the barrel band/shroud. That is if there is some physical interaction between them like the same barrel band/clamp also holding the air tank, etc.  I would assume that for the same reason (in some setups) the group could also be affected vertically.  If the air tank when being filled starts to expand and someway affect the barrel/barrel mount at a certain pressure (let’s say 200bar) it may shift POI on the way down from 250 bar when it drops below (for example) 200 bar and will no longer has any affect on the barrel mount setup.  I would assume this could be noticed only during a longer string of shots, not after one 5-shot group.   Just my 2 cents…


Hard to say from two groups. 

I don’t know much about the issue you mentioned but, when I have accuracy issues due to a problem with the gun, my groups are usually more erratic than that (I.e. they don’t stay on a neat line). I’d expect to see more flyers. 

The guns I have with metal barrel bands like that happen to be the most accurate ones I own. Not saying it’s because of the bands. It’s just a coincidence. They haven’t casued me any issues though. 

In fact, the only time I can recall having issues with a horizontal shift of the poi, is when the scope is not mounted properly or the scope rail is loose.