but maybe, like the UK limit the number of rounds allowed in a magazine - physically shorter 5-10 capacity
The only magazine limits in the UK are on shotguns. Rifle magazines - whether semi-auto, bolt action, lever action or straight-pull are entirely unregulated. I can use a 5-rd mag or a 100-rd drum mag (if I'm feeling flush and can afford the ammo!).
Biting the hand that feeds IT
