small-bore
Concise Oxford English Dictionary © 2008 Oxford University Press:
small-bore
▶adjective
- 1 denoting a firearm with a narrow bore, in international and Olympic shooting generally .22 inch calibre (5.6 millimetre bore).
- 2 N. Amer. informal trivial; unimportant.
'small-bore' also found in these Oxford entries:

