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Miracle Cure for Fussy Benellis!

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Miracle Cure for Fussy Benellis! Empty Miracle Cure for Fussy Benellis!

Post by gwhite Thu Mar 28, 2024 10:15 am

I help coach a collegiate pistol team, and I also serve as the team "armorer". We have twenty one Benelli .22's, about 50/50 split between MP95E's and MP90S's. I also have two MP90S of my own.

Over the last 15 years, I've had increasing problems keeping them all running smoothly. Most of the issues centered around reliable extraction & ejection. I have all sorts of tweaks I've developed to make sure the grip of the extractor is secure, and that has helped, but on some pistols, it's not enough. Having this many pistol to work with, I began to observe a pattern. Pistols that worked fine would suddenly start jamming after I replaced a broken firing pin. I have seen issues where a broken piece has chewed up the slide or breech face, but I couldn't find any signs of damage in many of the pistols. They also would get fussy about ammo. My two personal pistols will shoot almost anything. Some of the Team pistols worked OK if they were kept super clean, and only fed RWS Target Rifle ammunition. That is no longer being imported into the US, and costs over three times what we pay for Aguila.

Recently, we had two more pistols that went south after the firing pins were replaced. The most common failures were either the slide closing with the fired case in the chamber, or the extractor letting go of the case with it only part way out of the chamber:

Miracle Cure for Fussy Benellis! File

Because we have multiple pistols, I could swap assemblies around, and the problems followed the slides. I could understand the cases left in the chamber if the new firing pins added too much drag, but I couldn't figure out what was making the extractor let go with the case only part way out of the chamber.

About a year ago we needed to get parts for our sixteen Benelli Kite air pistols. I now have a contact at the factory who helped us with that, and he is also very familiar with the .22 pistols. I sent him an email with a description of what I'd observed, and my attempts to fix it. He immediately came back with an email that our firing pins were too long! They made a design change to the "head" a while back to try to reduce breakage, and at the same time decided to make them a bit longer. Here's a picture that shows the two versions:

Miracle Cure for Fussy Benellis! File

The old firing pins were 31.1 mm from the front of the head to the tip. The new design was 31.3 mm long.

I inventoried all our pistols, and found seven that had replacement firing pins that were 31.3 mm long. All of them had a history of being fussy, or in some instances, completely unusable. I cleaned them, and test fired them with 20 rounds of Aguila standard velocity ammo. One had no failures, but the remainder had at least 3 jams. The worst one had 13.

Apparently Benelli had discovered this problem a while ago, because the newest batch of 6 replacement firing pins I had were all 31.1 mm long. They have the same head shape as the newer one shown above, but they are a silver color, rather than the brown finish of the older "new" ones. I cleaned the six pistols that had jammed during test firing and installed the short firing pins.

Yesterday, we test fired those pistols. Five of the pistols did not jam at all firing 40 rounds of Aguila. One had some feeding issues, which were eliminated by swapping magazines. Afterward, that pistol also fired 40 rounds without a problem.

The hammer pushes on the back of the firing pin through the early part of the recoil cycle. The only thing I can figure is that the firing pins are so long that they are actually pushing the fired cases off the extractor. We have one pistol that can apparently tolerate that to some extent, possibly because its extractor has a larger gap, or other tolerances build up to act in its favor.

This has been driving me nuts for quite a few years, and I know some other Benelli owners who have struggled with the same symptoms. If you only have one pistol, it could be nearly impossible to track this down on your own. I also found that some of the firing pins made & sold by Larry Carter can be as long as the bad factory ones, and two of the pistols we fixed had those installed.

I hope this helps other Benelli owners out there. I know one local shooter who sold his two Benellis because he had so many problems with them. He has since discovered that he just can't shoot his Pardini as well as the Benellis, which matches my experience.

gwhite

Posts : 55
Join date : 2019-09-30

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Post by mprince Tue Apr 09, 2024 10:30 pm

Sounds like I have some guns to disassemble

Thanks

mprince

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Post by gwhite Wed Apr 10, 2024 9:30 am

I sent a note to  my contact at the factory, and asked about the feeding issues we have had with some pistol/magazine combinations.  I got some more info on the firing pin issues.

Apparently, Benelli decided that they needed to radius the rear of the chamber edge a lot more than they had done in the past.  In 2009, they changed the chamber design to include a significant radius.  I've never seen one, but I suspect they basically added a bit of a feed ramp to the lower edge of the chamber.  Pardini has a really large feed ramp on their pistols, but the firing pin strikes at the top of the rim.  On the Benellis, the firing pin hits at the bottom of the rim, and they found they had to increase the firing pin length by 0.2 mm to get reliable ignition.  

Our latest Benellis were bought before 2009, and have serial numbers in the 103xxB range.  We have 5 that were all bought at the same time.  They all arrived with VERY sharp chamber edges.  Unless you can find just the right magazine or shoot extra pointy ammo, they shave lead off rounds when they feed.  I've been slowly stoning a small radius at the top & bottom of the chambers, and that helps considerably.  At least now I know not to get too carried away or I will need to get longer firing pins.

gwhite

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Post by croesler Wed Apr 10, 2024 11:32 am

This is not only super helpful but its good scientific process to determine root cause.  Nice work!  The Benelli is the best kept secret in rimfire pistols, but, if there is going to be any problem (often not), its failure to eject that will be the vexing problem.  You have probably identified at long-last one of the chief culprits. Over time I've had at least 5 of these pistols and only had 1 that I could never quite get right.  This was an MP90s that seemed to have a "sticky" chamber.  Ultimately by cleaning the chamber within an inch of its life most of the problems were solved.  It had some lead build-up (older gun, shot a lot) that became an issue, and needed a small dowel with find grit sandpaper to cure.  Not saying that is a good solution, but it worked and didn't impact accuracy.  

The unannounced factory changing of part specs seems to be one draw-back of the Italian gun-makers. I've seen more problems with the Matchgun MG2 than I care to introduce, and it seems no gun or part is the same, and almost all have issues.  For MatchGuns and Benellis there is also a cure, and when found, they run beautifully with outstanding accuracy.  But the bugs can be vexing.  

Thanks for sharing your research!
croesler
croesler

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Post by gwhite Wed Apr 10, 2024 11:54 am

I love the Benellis, and really wish they would import them again.  Having access to well over 20 of them has allowed me to do some careful experiments to chase down several of the more subtle issues.  

Right now, the team's biggest issue is academic pressure reducing the number of students and the amount they can practice.  Pre-pandemic, we would continue to have a fair number of students come in to practice even after the National Championships were over.  Now, we are lucky if we get more than one or two each evening.  As a result, it's harder to collect data on how many pistols are truly fixed, or have other issues that were swamped by the firing pin problem.

gwhite

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Post by Fast G Wed Apr 10, 2024 5:08 pm

That is exactly the problem I have with my MP95. Either the spent case is still in the chamber or more often your first picture is the problem, spent still half in the chamber. I took the firing pin out and measured it and it's 31.3, but look at the wear pattern. 

Graham Miracle Cure for Fussy Benellis! Pxl_2013

Fast G

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Post by gwhite Wed Apr 10, 2024 5:13 pm

That's pretty typical.  I think they made the firing pins a tiny bit softer so they are less brittle, but you get peening from the hammer strikes.  The round back end ensures that the impact is well centered, which helps avoid snapping the head off if the face of the hammer isn't perfectly square.

gwhite

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Post by Fast G Wed Apr 10, 2024 5:28 pm

So do you think I should shorten the pin, from the hammer boss or the point? When the firing pin is fully inserted into it's housing, how much pin is protruding out of the breach face. I have the original and a spare, so I can experiment. 

Graham

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Post by gwhite Wed Apr 10, 2024 5:48 pm

The length of the pin that is important is the distance from the tip to the front of the head.  I have ground all but one of the longer pins we have (over a dozen) down to 31.10 mm.  On pretty much all of them, I had to also grind the bottom bevel a little bit to get it back to the original proportions.

gwhite

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Post by Fast G Wed Apr 10, 2024 5:54 pm

So just grind the head, this is my current length. Miracle Cure for Fussy Benellis! Pxl_2014

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Post by gwhite Wed Apr 10, 2024 7:12 pm

I hope that's a typo, but DON'T GRIND THE HEAD!  You need to grind the tip.  The back of the head has nothing to do with how far the tip sticks out.  You need to use the depth rod on the caliper to measure from the tip to the FRONT of the head.  It will probably be very close to 31.30 mm.

gwhite

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