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IH_784
To expand on my previous post, a well made kydex sheath has sufficient retention on it's own - no real need for the retention strap. That retention is part of the reason that people opt for kydex (along with the flexibility of carry options).
I carry fixed blade knives regularly...a few of the kydex sheaths were made for horizontal carry; so that's how I do it, and I've never had any issues with a knife coming loose. I'll grant you that none have the weight of the BK2; but, still, we are talking about horizontal carry. If it was inverted carry, I might better understand the concern (though I routinely carry that way without issues).
If you just like the style, that's a different story & I'm not trying to talk you out of it.
For Becker knives, I'll recommend azwelke. That's his username here; just add the dot com for his website.