There are Jones under-levers and there are Jones under-levers! The strength in regard to keeping the rifle on face depends on how the female lugs are attached to the barrel set. If they are in chopper-lump barrels they are stronger than just about any type of lock up. If however they are the earlier rifles with dovetail attachment or simply brazed to the bottom of the barrels then other forms of lock-up are preferable as to strength. The LeF is a weak system to be sure, and most are very old and were usually on black powder shotguns!

If properly attached to the barrels, and including a doll's head with a hidden bite it is very strong, and in that case it's only draw back is it is very slow to re-load and get back into action once emptied.