We take youngsters from about 8. We go on their build and their attitude rather than their age. We would be unlikely to take many 8 year olds.
Currently we have 74 members, and 28 of them are under 18. 22 of the 28 are student members and they are age 13 to 15. Student membership is a restricted category at our club with limited access and limited rights as a member.
As club guns, we have three rifles in general use, a S200, an Ultra, and an Original 25 spring rifle, plus a special which is a Brocock action in a home-made stock of about 3/4 size. Some juniors have access to rifles owned by their parents or guardians that have been modified to suit the smaller stature and the S200 is a common example as it's easy to modify.
We don't encourage the smaller ones to take up pistol shooting until they have got the strength and size in their hands.