The cheapest recipe / will be the one with less shot in it ...
My reloads for $ 12 ga are around $ 3.50 a box ( for 1 oz loads, at around 1225 fps ) ( I think I told you $ 4 a box earlier, but I see the price of shot is down at my club to about $ 26 a bag now:
Shot ( 1 oz ) $ 0.08 cents per shell
Powder is $ 0.03 cents per shell
Primers are about $ 0.03 cents per shell...
so loading 1 oz / or even 7/8 oz in a 12ga will save you some money...
the rest of it is buying the components based on the performance you like / but the most popular powder around here 10:1 is Hodgdon Clays in 12ga with the one of 10 guys using Unique.....
and 10:1 guys are using Rem STS hulls
primers are all over the board - with guys using Chedite, Win, Rem, etc ... consensus is REM or WIN are better primers but the others are a little cheaper right now.
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But yes, get in with the guys at the local club - ask around and see who does some reloading / and who may have a machine for sale .... and you'll get all kinds of responses. You'll have to figure out who is giving you "quality data" vs just flapping their gumms ..... Remember, free advice is worth about what you pay for it .....
But at every club you'll find guys that are really serious about their reloads / and some guys that are really careless ( don't use formulas, never clean their presses, etc ). It was rainy and nasty up here over the weekend / and the football games were bad news ....so I spent a couple of hours taking my 12ga and 20ga hydraulic MEC's apart, cleaned it, checked everything, anti-static stuff on bottles, lubed everything .... just because !! Then went over to my local indoor range and put 8 boxes thru a couple of my handguns in 9mm and .45 acp ... It was a great day .... and the loader is good for another few thousand shells, and I feel better about it .....