I have 4 of the mounts, used for the following:
338LM Remington 700
338LM DT SRS
50bmg Steyr HS50
50bmg Serbu BFG50A
Never used rosin, never has any slipping issues with any of them through many thousands of rounds.
The one on my Remington developed a hairline crack in the upper clamp at about the 1500 round mark, and when I contacted Spur about it, they were quite surprised and said they have never seen an issue like that, so they asked for photos and torque specs. (20 inch lbs as per spec). Once they confirmed that it had indeed broken they shipped me a new upper clamp ring free of charge, have not had a problem since.
Lots of good info in this thread here, thanks everyone. I wasn't sure if it was going to be a pain in the @$$ to mount, and I didn't buy any rosin, just threw my Steiner in there, crossed my fingers and hoped for the best. The instructions said to tighten the ring screws down to 15-25in/lbs, so I went for the max.
Kevin, did you need to go that far with your 50s?
Here's my unboxing, also with a cell, but less blur, lol!
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God's Balls, that is one robust mount and cost more than several of my first scopes, lol!
Not really sure when the rifle arrives, so it'll be a while before I take it for a test drive, but I'm pretty impressed so far.