if you have a barrel shortened on a centerfire to under 18.5 by you or a gunsmith it becomes restricted.if it is a production rifle,but not semi auto,under 18.5 it is fine,like a winchester trapper or marlin camp carbine,they have 16 inch barrels.but you can have shotgun with 12.5 barrel if just a pump but overall length is over 27 inches.as for rimfires you can goes as short as 11.5 and have up to 150 rounds magazines.in canada you can only have 5 rounds max in a semi auto rifle and ten in a pistol.unless the rifle is capable of using 10 round pistol magazines,like the barretta cx storm carbines.you can own 30 round magazines but have to pinned to take no more than 5 rounds.also a lot of the fun guns you can use in the states are prohibited here or restricted ,any AR variant restricted.FAL,AK and other variants outlawed unless you have special license .plus there is some different rules for some special firearms.also all handguns that shoot 32 caliber and under are prohibited and all other calibers with a barrel shorter than 4 inchs.overnight some 500,000 weapons were made illegal in canada.but we can buy russian and chinese weapons,sks,svt 40 and cheap handguns.sks here can be bought for 180 and chinese m 14 for 450.also we can send guns though the mail to individuals not to a FFL dealers.this should make it clear as mud ;D