As a rule each airline formulates their own list of prohibited items. But, there are certain dangerous items which may not get taken onto a plane in any circumstance.
FLIGHT REGULATIONS FOR WEAPONRY: Use this guide to check which guns or firearms are not permitted as hand baggage.
In some cases, some items may be allowed as hold luggage when taking a plane flight in or out of the United Kingdom.
Flight passengers are not permitted to take any guns or firearms (including air rifles and starting pistols) as hand luggage.
However, check with your airline before you travel because you may be able to take certain ammunition items as hold luggage*.
You cannot take any of these guns or firearm items as hand luggage or in the hold:
Flight Restrictions Gun Ammunition and Firearms; UK Rules Updated 2017