You'll get ~20% longer range at dawn/dusk if you go with the 2.5-10x50 or 4-16x50 Monarch, which have equivalent glass to the M223/M308 models. Both Monarch scopes will allow you to use up to about 10X, whereas the 42mm M308 will be limited to about 8.4X for the same lighting conditions. How high a mag you can use depends on the lighting and our age. The 50 mm always has an advantage over 42 mm in low light, however. For pig hunting that could be important.