71 Collecting and Issues on NM Cards

[TCannon56to71]

I am new to the forum. I collect 6 sets between 1956 topps and 1972 topps, but my 1971 set is one of my favorites. I previously collected a full set and sold it 6 years ago, and my current set is about halfway complete and I don't collect anything worse than PSA 5 or thereabouts for my personal set, of course with many of the cards being much better than that. In buying 1971 lots there have now been multiple times I have purchased weird looking 1971 cards. These cards appear NM or close, they have edges that seem unnaturally straight to me from my experience handling 71s, and the top of the card is almost uniformly shorter than most of my cards. In other words, the black space above the "White Sox" on the John Purdin I recently purchased is very short. When you align the bottoms of a stack of these cards, the tops appear different lengths, in other words you stack 25 cards, you hold them and the bottoms of the cards are all touching your fingers, and the tops of the cards appear "rough" on top because of being slightly different lengths. I sent back a full 200 dollar shipment a month ago and told the seller no hard feelings but that it might be factory error, but I simply was not interested in 30 1971 "factory miscuts". Can someone with even more experience than me shed some light? I understand that trimming is an issue in this year, but the more I look for this the more I find. And it does not seem simple, some of these cards appear short but then you find they are the same length as graded copies at least to the naked eye... and I am not referring to "maraca" cards that shake around in the psa holder. I have one of those as well. Any info or any experiences others have had collecting 1971 would be so much appreciated.