Benelli MP90S .22LR feed "contact"

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I considered the 9" tool, but it's really long and the shorter one is easier to handle. They're super-nicely made by Whitney Tool in Indiana btw.

The felt bob was a standard Brownell's tapered cone one, the 080-560-103WB listed here.

The cone-shaped stone wasn't anything special, I think it came out of the Dremel junk box. It was maybe 1/2" diameter at the back, and went down to a pretty good blunt point. He put almost no force on it, just kind of used it to twist on the inside crown of the bevel. The goal was to break any edge and put down just a touch of roughness so the polish had something to bite on. The Cratex rubber abrasive points you mention are great, but they would be much more aggressive for this goal, IMO.

Before we started, I had given the barrel and chamber a thorough soak in BoreTech Rimbore carbon/lead cleaner, by plugging the chamber and filling the barrel for a few hours. Dumped that out and gave it enough passes to work up lather on the brush (20 or so?), then inspected the chamber, which was uniformly gray and scratch- and ridge-free. I would definitely not plan to go in there with any compound, on this gun anyway.

[Gwhite]

Sounds good! Thanks!

Time to go shopping... I think I will get the 9" extension and cut it down if I feel I need to.

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A range report after putting a couple hundred rounds through it. The feed issue is definitely gone. The pistol cycles well, and each cycle has the "tick-tick" feel instead of the "bang-thud" feel of a hiccup. Very pleased.

Unfortunately, I did have several FTE's where the brass came only halfway out of the chamber, or in one case actually rechambered, empty. I am chalking this up to my aggressive chamber cleaning, and in fact it seems to be going away. I often get this behavior on the first 5 or 10 shots after cleaning, it's just a little bit surprising that it was happening after 50. So, not concerned but thought it was worth mentioning.

[edit] Oh, one more note, there is now only carbon visible below the chamber opening, and it's basically just a dusting. Previously, there would be a small blob of wax and lead there, after this number of rounds. Thumbs-up.

[Gwhite]

We've had a sudden rash of FTE's in 3 different Benellis. The symptom is that (typically) round 1 will only extract about 3/4 of the way, and then the extractor lets go and the bolt continues to the rear. It picks up round 2, which it jams into the case from round 1.

One most Benellis, the extractor gets pushed to the side slightly when the bolt closes. Ideally, as soon as the bolt begins to move reward, the extractor hook will pop back onto the case fully and you are fine. If the extractor gets dirty or the oil dries out, it can slow down or hang up, at which point the grip on the case becomes tenuous. The extractor spring may also be worn or compressed. Larry Carter actually had slightly stronger spring made up in the USA to help with extraction issues, but with his passing, it will be a while before those are available again.

I've been re-grinding the tips of the extractors to fix the geometry (see http://www.targettalk.org/viewtopic.php ... &#p274685) to hold the cases up into the bolt face. The problem I ran into is that if you have to remove a lot of material, the way I was doing it forces the extractor to the side even more when the bolt closes. You really need to grind it matching the sloping angle on the left front face. That matches the extractor slot in the barrel, and minimizes the deflection.

Here's a picture of an extreme case. I had to remove a LOT of material to get the tip angle right to hold a case securely on the bolt face. The one on the left is un-ground. When the front face is in contact with the extractor slot, the one on the left gets pushed a long way off the rim:

The picture below shows how much the extractor got pushed aside. When I re-ground the face, and not just the tip, things got much better:

I have seen a case where cleaning the chamber thoroughly makes things worse. I think this is because the grip on the case is too good, and is messes up the forces, speeds & timing of things. A drop of oil on the case of the top round in each magazine helps, and once a little bullet lube & carbon build up in the chamber, the problem goes away.

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Thanks, I remember that thread now, and my extractor is definitely on the "pointy" side. It also does have Larry's upgraded plunger and spring, and yes it does move slightly sideways with a round in battery. Oh boy, more things to ponder!! OTOH, I am betting the problem vanishes with a bit more seasoning from use.

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Ok, one more followup regarding the lead-and-wax-shaving behavior, or should I say non-behavior! Since this polishing, the pistol has practically stopped building up wax and lead below the chamber, and it cycles beautifully. There are about 400 rounds through it when this picture was taken, the last 300+ flawlessly. Happy, happy.