In spite of the 410 being handed to generations of kids as a starter gun, it is actually a poor choice. The 410 is nicknamed "idiot stick" as only an idiot would handicap themselves so much. It is a very fun gun to shoot but it is geared more to someone who knows its limitations well and can work inside them. It is my favorite bore to use but also frustrating.
My 410s are mainly used on clay pigeons these days. It is lacking in pellet density for most hunting making it a special purpose/situation tool. The single shot does get a fair bit of use for pest control around the house, I shot a red squirrel out of the yard yesterday. My wife will occassionally use it to rid her gardens of a rabbit but she generally orders me to do so.
Back when the woodcock season opened on Sept 1 the 410 was my main gun due to the short range and small bird size the small shot charge did not tear birds up much. When grouse opened up a couple weeks later I would switch to a larger gun.
I also used the 410 for dog training as I didn't want too messed up bird for the dog to retrieve. The occasional cripple, especially when using pigeons, was also a great training opportunity for a young dog.
A 410 would be a fine squirrel or rabbit gun though I would prefer a 22 LR or even air gun over a shotgun. With an effective range of about 25 yards, the 410 doesn't give one much advantage over a rifle. A 410 makes a good close range dove gun if one has the opportunity. I've used mine over watering holes a few times and that can be a great time.
What I have learned is #7.5 shot is the most useful in the field. #8 shot is nice but it is difficult to find. #8.5 is my favorite target size as well as for training birds. I reload most of my own shells with the last two sizes. #9 is a bit small for most use though it is excellent when jump shooting English sparrows from nesting boxes. #6 is the largest size I would use as patterns are pretty patchy with it. I have a box of #5 shot I am using up on red squirrels, I've had to use more than one shell to bag one of the buggers as at even 20 yards there are gaps large enough to miss the squirrel. Or, put a pellet someplace non-vital.
I prefer 3" shells for field work as more pellets is more pellets. The pattern percentage may be lower with the heavier shot charge but there tends to be more pellets in the usable pattern. 2.5" shells are mostly target and dog training with some use for pests.
The 410 is a fun shell to use but it can be frustrating. If one shoots it much, reloading is the best course to take as you will recoup your investment money quickly. Keep your empties as they tend to be I demand. Even if you don't reload, you may be able to trade/sell them to someone who does.
