Birmingham Small Arms.
No sn data I know of
Here is the BSA link (below). I suggest you ask them directly.
"Best" is a relative term. Ultimately, it comes down to what works best for you. Personally, I'm fond of the BSA Martini .22 rifles.
BSA made several different air rifles. Unfortunately you did not state the model number and that is critical. You could try to contact BSA and ask them. see the link below.
1919-1938. All BSA rifles produced between WWI and WWII were marked "STANDARD." They are all quite valuable if they are in Good to Excellent shape.
BSA actually stands for "Birmingham (UK) Small Arms" they first made guns; hence the 3 crossed rifles on the badge. Yamaha, who first made pianoes, copied the idea putting 3 crossed tuning forks on their badge.
BSA made 8 different Meteor model rifles starting with the MK1 to 6, MK 6 Carbine and a Super. Identify your model and state the condition of the rifle to get an estimate of value.
I am not sure exactly what you mean by "Full Power" so I assume you are asking about one that is NOT sold in the UK directly. The Mark 7 is the latest Meteor model. It comes in both .177 and .22 cal. It is made by BSA. (see the link below.) It is a Springer. BSA does make more powerful models in the PCP class of air rifles. The last reported price was around $300
The BSA National Council. They take thousands (if not millions) of recommendations for new badges a year, and occasionally create new ones. The most recent example would be Scuba Diving.
This rifle must be rare, I can not find any information on it. I did find the following information on these BSA rifles in Mint condition. ( Yes it would be a collectible) Goldstar $450 Superstar $420-$480
Birmingham Small Arms company. The early trademark was 3 crossed rifles. Birmingham, UK was fairly central to the British motorcycle industry.
BSA has made over 40 different Air Rifles. Exactly what model are you asking about. Most are break barrel models. Simply cock the barrel down load the pellet and restore the barrel and fire. But it would be helpful if you listed the model number of the rifle you are asking about.. ( See the link below.)BSA have a range of official tutorial videos on You Tube. This one shows how to load a spring air rifle Simply do an internet search for 'BSA guns you tube' to find the full range of tutorial video's.