My buddy bought a model 99 that has some issues. He ended up giving it to me.
It failed to eject consistently, closing the bolt on the empty. Sometimes It closes above the live round, and sometimes it just barely catches on the edge of the ejection port. Ejection is erratic. It sometimes will throw the empty squarely to the right, sometimes to the front.
So far I've cleaned the chamber really well, and the rest of the gun as normal. The firing pin is free, the extractors move free, and the right one has the sharp hook as it should. The barrel recesses for the extractors are not filled with crud and it the extractors move freely into them, and eject live ammo perfectly. The barrel doesnt have any noticeable dimples from the firing pin, and ammo does not scrap or bind when dropped into the chamber.
Replaced the recoil spring, and hammer spring.
Replaced the extractor springs.
I have a 70s vintage model 60 so I've tried to narrow down the problem with the 99 by replacing parts out of my 60 one at a time.
I replaced my bolt assembly, no change, replaced original.
I replaced my lower assembly, problem fixed.
So, I inspected the lowers and it appears to me, that the lower assembly is from a different vintage gun, or more likely, a collection of parts from various model 99/60s. The feed throat has 4 pins, where as the one from my 60 only has 3. The ejector is the type that doesnt eject off the wire. And the ejector is not rounded much. My model 60, is rounded like all get out, and still ejects like it should.
The shell lifter was different, and after watching the action cycle by hand with ammo in the gun, It appeared that the nose of the shell was being thrown up into the path of the ejecting empty, thus knocking it off the bolt. I shaped the shell lifter to match the one from my 60 as best I could. This helped the problem a lot. It went from 2 or 3 jams in 10 shots, to 2 or 3 in 20 shots.
I then replaced shell lifter with the one from my rifle with no improvement. I put the original shell lifter back, and replaced the feed throat. Still no improvement.
Im now thinking, maybe it was a compound problem. The shell lifter being the principle factor, and something else being secondary. I've not changed the extractors, but I did change the 60s bolt in its place. However, when I did this, I didnt shoot a bunch, just a mag, and It was before I had reshaped the shell lifter, so I didnt notice any change.
I did try different ammo several times during the process of elemination. Thunderbolts, winchester wildcats, winchester 333, CCI Blazers, winchester round nose in the 100 round plastic boxes (I cant remember what it was called).
Any thoughts?
Thanks, ~Bazoo