I put one the rifle models on a .50 cal muzzleloader, used 100g of powder and 300g sabots, lots of shots, never come apart, never lost zero. My friend also has the same set up though he uses 360g sabots, still never a lick of trouble.
Sold mine and went back to peep sights. Another friend, who bought it, uses it on his .50cal and still no problems.
These are the 1.5-5X32mm, with the load producing around 30-40 ft. lbs. of recoil.
Not bad in my book, good light transmission till 30min. after sunset.