Air rifle butt weights

[JSBmatch]

Its quite common to see on the 10-m shooting circuit air rifles with added weight (some times wheel balance weights) stuck around the butt area, is there a tech reason, as I would have thought this would make the barrel/muzzle end too light and will be less steady. As we know, 5.5-KG is the limit. I can only assume its for the butt to sit heavier in the shoulder. Any ideas

JSB

[methosb]

Some positions, body sizes, heights just make the rifle too front heavy so you gotta add a bit of weight at the back to get the balance right. Also it can be good, as you say, to make the back end sit more solidly in your shoulder if you feel it is too floaty.