Can't argue that if you wait for the sales on Estate, Federal or Remington Gun Club Target shells. the cost to reload 12s and 20s is about the same. Buying in bulk, I can load a box of 12 gauge for about $5.25 and for 20 gauge a little less. I can usually get the promo target shells for about $55.00 per flat all in, so add in the cost of the equipment and my time and I am not saving money, but I would like to think that my reloads are at least as good as Winchester AAs or Remington STS premium target ammo and maybe better, so those prices are a savings. Plus I like doing it and find it relaxing and since so few reload 12s and 20s anymore I have not had any problem finding powder.
Of course you can then also load what you want like 7/8 ounce handicap 12 gauge loads or 1 1/8 or 1 1/16 ounce 16 gauge No. 9 Skeet loads.
Even on super special from Midway when I got Winchester AA 28s and .410s for $75.00 a flat delivered, I can load those for less.
But then, unlike Bench Rest, there are shotgun events that require you to shoot factory ammo!
Bob