This will be the 3rd seasons shooting hevi 13 7s. First year I was very impressed with the numbers although I don't remember them exactly, they were around 280s. Last year I polished my barrel prior to patterning and got less than desireable results. Still good, and plenty enough to kill a turkey, but not much better than I was getting with 6s. I almost thought I screwed my barrel up polishing it.
This year, on a nice warm day I tried some of the lot numbers from last year (300857) with the shells I bought this year (380753). The 300857 put 211-224 in a 10" circle at 40yards.. the 380753 put 283 in the 10" at 40. Crazy the lot numbers can have that much of a difference.
Hevi-shot has always had quality issues and this is probably the biggest one. For 6 dollar a piece shells you would think they could provide some consistancy between lots. I still shoot their products now and then but not ad much as i shoot lead.
I've noticed a few things, most of the 6's I've had all shot well but I had one shell that seemed to have nothing in it, bet it didn't have 200 pellets total on 40 inch paper at 40 yards, reported it to Hevi and they sent me a new box. Others all shot over 200 in 10" with my setup, so I guess that was an oddity