50k has worked in everything I've tried them in.
They're a traditional tangent design bullet, rather than a more secant/VLD. I've not found them to be particularly sensitive to depth and I suspect this is why.
I suspect the 50k recommendation is because keeping them that far from the rifling helps keep the pressure down more than anything else.
As for suitability at that distance. No comment. Speer do a 90 and a 115 grain gold dot though - would be very tempted to try one of those.
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