I have been going out lamping with rifles air and rimfire also with Lurchers for the last 35 years, this is a fantastic way of pest control and good fun too.
No one as yet has mentioned about weather conditions and the position of the Moon, in my experience the best bags I have had are on Moonless nights after some showers of rain.
I have also noticed that Rabbits seem to have two feeds and be out about 1 hour after dark falls and then another about 3 to 4 hours later.
Hope this info improves your bags good hunting.