TargetTalk

Can anyone help me find a firing pin and extractor for my MP90s? The original pin broke. I had a replacement that I bought when I bought the gun new but I’m having all kinds of new extraction problems since I installed the new firing pin.

Have you checked the length of the firing pin? This is exactly the problem we had until I found out about the length problem with the newer pins. They should be very close to 31.1 mm from the tip to the front of the head, assuming you have an older pistol.

The other thing to check is that the broken bits of the old pin didn't damage anything. I've seen that happen, but in my case, it cause feed issues because of a burr on the bolt face.

Being an old Benelli shooter I now have the great pleasure of un-fuzzing one of the club Benellis that, well, does Benelli things.
Its old and worn but I will throw my secret magic spells at it in the hope something might work.

Anyway, while tearing it down I found a peculiar thing, the bolt is magnetized. So much so that I can pick up all internals and smaller things with it.

I cant recall I ever come across this issue before, it might not even be an issue but I found it note worthy.
Ill give it a go on the old watch demag and see if that does anything.

VERY interesting! That's not something I've run across. Thanks for sharing that. I would expect that it could make the extractor and recoil spring systems a tiny bit stickier.

I often re-grind the extractors a bit. That process frequently magnetizes them, so I'm used to demagnetizing stuff.

Gwhite wrote: ↑Sun Aug 18, 2024 11:28 am VERY interesting! That's not something I've run across. Thanks for sharing that. I would expect that it could make the extractor and recoil spring systems a tiny bit stickier.

I often re-grind the extractors a bit. That process frequently magnetizes them, so I'm used to demagnetizing stuff.

Havent had time to test it after putting it together again, but at least the demag was successful.

My very scientific armchair theory is that the recoil spring and guide rod acts as a coil when the magnetized bolt runs over it and that may induce a voltage making things work funny.

Then again, previous user seem to be a fan of lubrication, not so much a fan of proper cleaning.
After a complete strip down and 45 min in the ultrasonic finding the parts was like playing battleship. So that hopefully helped a bit too.

Finally had time to test the now demagnetized Benelli at the range.

It worked pretty good, but I had 2 out of 70 shots ending up as a failure to eject, both being the last shot in the series of 5.
I also noticed the spent brass was ejected in diffferent directions from time to time, and the felt recoil was a bit different shot to shot.

This of course need further inspection.
Didnt have to look for long before finding a deviation I missed earlier, the extractor sitting high in the bolt creating a gap between the extractor hook and the case rim.
Here is another angle, first image not pressing down on the extractor, second pin pressing down compressing the extractor spring.
This is most likely due to time and poor maintainance, grit has over time crated a honing paste hollowing out the extractor seat in the bolt
Best way to adress this would probably be to bore out the extractor seat hole in the bolt, seat a steel rod, machine the top and re drill a new hole creating a steel liner.
I dont have the tools or the skill to perform that type of work so instead I will jerry rig an attempt to add material to the extractor tap

To be continued (most likely)

Usually the extractor corners wear faster than the bolt. I'd start with a new extractor. Also, see:

viewtopic.php?p=274529#p274529

and:

Gwhite wrote: ↑Sat Aug 31, 2024 8:47 am Usually the extractor corners wear faster than the bolt. I'd start with a new extractor. Also, see:

viewtopic.php?p=274529#p274529

and:

Benelli Extractor Tuning.pdf

Thanks for the link, I forgot to mention that precvious owner being an old man and therefore way wiser than the whole staff of engineers at Benelli had a tool maker fabricate an extractor out of thardened tool steel aka a ’foreverstractor’
As my measurement below the hook is .02 it would be in line with the statement that anything above .015 is a problem

That may actually be a mistake. You want the extractor softer than the bolt so it wears and not the hole in the bolt, which is WAY more difficult to repair.

Also, before you drive yourself crazy unnecessarily, have you seen this?:

download/file.php?id=27790

Gwhite wrote: ↑Sat Aug 31, 2024 9:14 am That may actually be a mistake. You want the extractor softer than the bolt so it wears and not the hole in the bolt, which is WAY more difficult to repair.

Also, before you drive yourself crazy unnecessarily, have you seen this?:

download/file.php?id=27790

Yes exacly, this way the bolt has turned into the sacrificial part and not the extractor as its supposed to be. Hence the need to now adress the issue of a worn hole in the bolt.
I think this pic sums it up

That's certainly a pretty big gap. You might consider at least trying a new extractor, or getting another custom one (or two) fabricated that is shorter. That may be easier than trying to fix the bolt. There are lots of fabrication techniques available now (laser cutters, waterjets, wire EDM) that would make that a lot easier than in the past. Alternatively, you could see if you can find a micro-welding shop that could add metal to the extractor you have.

Worse comes to worse, it's not a complex part. A few quiet evenings with a magnifier and a file & you could make a new one.