Blackjack has an interesting history; you can run a search on Blackjack here at BF and have enough reading material for the summer. The general feeling seems to be that Blackjack had good knives when their product was manufactured in Japan. In the later years (early to mid-90s) the company started having financial problems and started putting out inferior product. There have even been some accusations that the company claimed they were using one steel when, in fact, they were using another. I take it that this was at the very end when the company was doing anything possible to stay in business. Along the way, Blackjack bought Ek Knives. I've been told that the Ek Eks are much more collectible than the Blackjack Eks. Former Blackjack employees have posted here and in other forums defending Blackjack, but direct questions about specific accusations have gone unanswered as far as I can tell.
An interesting side note -- the former president of Blackjack, Mike Stewart, ended up over at Marble's and helped resurrect that company's knife line. Unfortunately, I've lately seen several posts about quality-control problems at Marbles.
Don't get me wrong -- I don't want to come across as a Blackjack-basher. I own several of their pieces. It just seems like they might have gotten themselves into a tight spot and did whatever they had to to try and pull through. Unsuccessfully, as it turns out.
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"I can't believe you stabbed me with this cheap piece of mail-order sh*t"
James Caan in 'Eraser'