My pivot lever 10 gauge is an E grade SN 10,515. There is no spring in the hole in the barrel lug where its stem fits. It does take an intentional effort to remove the extractor which is done by Springing the stem itself. When re-installing there is obvious interference between the top of the extractor projection & the bottom of the slot in the rib extension. Again the Stem must be sprung to re-install.
My next Lefever up the laddder is a G grade two hook gun, SN 20,633. Guess what, it indeed has a flat top extractor with no slot in the rib extension & the extra guide pin for alignment. It does however have a short slot milled in to the upper forward end of the extractor stem with a closed end. This is engaged by a screw in the forend iron when the forend is snapped on. With the barrels off the gun the extractor can be simply slid out. This gun does not have that slot in the stem.
This is a quite low SN for an H, am guessing it is a small hook gun as all the Large hook guns I am familiar with do not have the extractor stem visible forward of the hinge joint.
On my lowest numbered Large hook gun, a G SN 29,471 they had gone back to the extractor projection & rib slot. This seems to be continued on through remaining production & these have the slot blocked as mentioned. I had simply forgotten I had this one gun with the different set up using the guide pin rather than extractor projection as that was used both earlier & later.
On this early large hook G though it appears after the extractor was installed the walls of the slot were given a slight staking to prevent it coming out. If the extractor had to be removed this staking would have to be removed & then be re-staked after re-assembly. I like the screw or block retention a lot better.
I would bet this gun had some system of preventing the extractor from coming out when removing shells or empties with the gun assembled. Will probably take some careful searching to figure out what & where it is.
