In 12ga and 20ga ....
I've shot a few flats of B&P ...nothing special about them. About the only time I bought them / was when I flew somewhere...and that was the premium load they had for sale, so I'd buy a flat. I never kept the hulls or reloaded them when I traveled. One of the kids pulling targets was usually happy to have them ..and policed them up.
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For the last 20 yrs or so ....
For tournaments I shoot almost exclusively Rem STS or Rem Nitro shells...usually new, if its a big tournament. I still keep 5 or 6 flats of new shells around ...
For my own reloads ...for practice ...its 100% Rem STS / Nitro as well.
Once in a while, if I'm shooting a semi-auto ---( like in the rain ) and I want to shoot a throw away shell, I'll shoot a box of Rio's sporting clays loads.
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From the 70's thru the early 90's I shot exclusively Win AA's - new and in my own reloads. When I got back into shooting ..especially into sporting clays in the 90's I switched everything to Rem STS / Nitro hulls on my reloads...so that's what I bought for new flats as well.
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I find Estate is a really dirty shell...so I avoid those unless I travel and that's all I can get. I was never a Federal fan ...or Fiocchi ...