Put extra 2-stroke oil in the mix, maybe a bit of diesel aswell, then she'll smoke like f**k, works for us!
we use a combination of terriers and airguns, and the odd overkilled 12b rat! in the grain bins and roof spaces we use the airguns, outside and downstairs we use the dogs. both have they're place! went out last night, shot 4 rats up top in the bins, and the dog had 2 and a mouse downstairs!