Welcome! First please turn off your cap locks.
THAT IS CONSIDERED SHOUTING
And make it hard to read.
Yes, good pics help a lot! Well lighted, plenty pixels in focus. Also- uh- what is your question? Have not asked one yet.
In the meantime, your rifle is the classic SMLE Mk III. Later known as Rifle #1, Mark III. Markings? Made by Birmingham Small Arms (BSA). All military arms in Britain were the property of the monarch (GR is George Rex, or King George) and it was made in 1918 (you have a WW 1 veteran) Ammo is correct for that rifle.
Here is a TON of reading for you. http://www.surplusrifle.com/smle/index.asp
One of the best battle rifles ever built.