LAWS COVERING THE UK
Original Enfield's, Snider's and many other period guns do not require a fire arms certificate by virtue of the 1968 Firearms and Licensing Act, section 58 part 2, as these are classed as being antique, with obsolete calibers and may be collected as a 'curio'.
It is illegal to sell or otherwise transfer a shooting gun in the UK without it having been proofed either in the UK or one of those countries with similar national regulations and with which the UK has reciprocal agreements. A muzzle loading gun or rifle made after September 3rd, 1939 is, by definition, not an exempt antique or curio and is subject to the provisions of the Firearms Acts unless it has been deactivated to quite strong requirements and cannot be restored.
Fire Arms Certificate (FAC)
If you shoot or intend to shoot a rifled weapon you must then have it covered by a Firearms License. Under section 58 part 2 you may purchase the gun as an antique and curio but to use it as a 'gun' then it must be covered by a FA License.
Equally if the rifle is modern and made by say Parker-Hale or Davide Pedersoli then you will need a license prior to buying / shooting.
Shot Gun Certificate (SGC)
If you shoot or intend to shoot a musket (smooth bore) weapon you must then have it covered by a SGC. Under section 58 part 2 you may purchase the gun as an antique and curio but to use it as a 'gun' then it must be covered by the appropriate license.
Equally if the musket is modern and made by say Parker-Hale or Davide Pedersoli then you will need a license prior to buying / shooting.
To buy / keep / possess and transport Black Powder you must apply for an explosives license. Application forms can be obtained from your local firearms licensing department. A simple Google search will give you the correct phone number.
When you have your Powder License (It took me over a year to get both my FAC and Powder License) you will then need to inform the 'Health and Safety Executive' and they will issue a license in order that you can transport the explosive in your car.
As a note the powder must be stored in a suitable container attached to a solid wall at the address on the license. Peter Starley at MidwayUK makes / supplies the suitable boxes.
The above is only a guide so if you have any questions or queries please direct them at your local firearms officer / firearms dealer....Infringement of the laws covering a Section 1 firearm, in the UK, carries a mandatory 5 year prison term - So don't be afraid to ask!
Click on this link and the forum chat here to see an Enfield - converted to a Snider and then re-converted in the more recent past (1960s, 1970's) to a muzzle loading Enfield, so that the rifle could be kept as an antique rather than on an FAC (at this time Snider rifles were required to be on a fire arms certificate), provided it was never shot....The problem is that this rifle now falls outside 'proof' and almost certainly falls outside Section 58 (2) of the Firearms Act 1968....And tested to the letter of the law may see the owner in serious problems with the Crown Prosecution Service...
For further reading please look at the following:
Firearms Act 1968 - This link takes you to page nine of document which as details of section 58 (2).
The Manufacture and Storage of Explosive Regulations 2005 - From the MLAGB web site.