Miracle Cure for Fussy Benelli .22's!

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Gwhite
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Miracle Cure for Fussy Benelli .22's!

Post by Gwhite »

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:

Partial Extraction (sm).jpg

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:

Old vs New Firing Pins (bottom).jpg

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 ones, but they are a silver color, rather than the brown finish of the older 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.
-TT-
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Re: Miracle Cure for Fussy Benelli .22's!

Post by -TT- »

Firing pin protrusion is definitely a problem! In my experience, it generally prevents the rising round from seating in the "pocket" at the front of the bolt. The rim bumps into the pin and everything goes haywire. This has happened to me if I let stuff build up in the firing pin channel, and at the back of the head of the pin.

Question, have you tried filing off 0.1mm from the tip of one that's malfunctioning, or increasing the bevel at the lower edge? Also, have you compared the headspace depth of the bolts?

Looking at my small stock, there are several colors, but all have the rounded hump pictured at the right in your photo. None is silver, they're black, brown or dark gray. I think the black or gray ones might be LGI's updated design, they have a little less hump. All measure 31.2mm or less - one brown one is 31.0. My MP90S is running like a clock with whatever it has in it right now, perhaps I'll measure that one soon!

One other observation, dryfiring without a plug can sometimes lengthen firing pins. I believe the undamped shockwave rings the pin like a bell, and it stretches. I've seen Pardini pins do this for sure. Of course, I never dryfire my Benelli this way.

Thanks for this!
Gwhite
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Re: Miracle Cure for Fussy Benelli .22's!

Post by Gwhite »

If the pin doesn't stick out too much, the bevel on the tip usually takes care of pushing the pin back into the bolt. I don't know that I have ever seen a pistol misbehave due to dirt build up in the firing pin channel, but it's certainly possible.

The black firing pins are probably Larry Carter's. They have a sort of hemispherical head, rather than cylindrical. I found them to be less prone to breaking than the original factory pins. The curved head is intended to eliminate off center strikes that can snap the head off over time. Larry made a big deal about working with a metallurgist to pick a better steel and heat treating process than the factory used. I've had the various alloys analyzed, and I've done hardness testing, and there's not a huge difference. About the time Larry was running low on his pins, the factory came out with their pins with the cylindrical head geometry. Most of the failures I've seen are pins breaking near the tip, which is pretty much the same geometry on all the different versions.

I have some more testing to do on other pistols, and once I've removed all the long firing pins, I want to figure out a fixture to help accurately shorten them. If it was just for one, I'd stone it down by hand, but I may have over a dozen to do.
-TT-
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Re: Miracle Cure for Fussy Benelli .22's!

Post by -TT- »

Gwhite wrote: Sat Mar 30, 2024 12:18 pm If the pin doesn't stick out too much, the bevel on the tip usually takes care of pushing the pin back into the bolt. I don't know that I have ever seen a pistol misbehave due to dirt build up in the firing pin channel, but it's certainly possible.
In my case, the rounds failed to chamber properly, because the rim end failed to rise before the bolt jammed the cockeyed cartridge forward. The channel was pretty gummy owing to me trying some extra-greasy ammunition. I discovered a paper Q-Tip shaft is a perfect fit for cleaning! :)
The black firing pins are probably Larry Carter's. They have a sort of hemispherical head, rather than cylindrical.
Thanks, it seems so, the mushroom is curved in both directions (black/LGI on left, brown/Benelli on right). The dark gray one is the same shape, I guess it's an LGI but has a less thick coating/anodizing.
img1.jpg
img1.jpg (23.37 KiB) Viewed 8129 times
I observe that the LGI pin has significantly more bevel at the lower edge of the tip. The lighting is a bit tricky in the photo but it's quite noticeable in hand. This particular pair measure LGI=31.04mm, Benelli=31.18mm.
img2.jpg
img2.jpg (31.78 KiB) Viewed 8129 times
Gwhite
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Re: Miracle Cure for Fussy Benelli .22's!

Post by Gwhite »

When I was still chasing the "too much drag" theory, I was concerned that the hammer was dragging on the sharp lower edge of the head of the factory pins. I think ideally the hammer should hit the rounded back of the center rib on the underside of the slide before it hits the bottom edge of the firing pin. I was preparing to grind down the bevel to see if that would help when I was informed of the length issue.
Gwhite
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Re: Miracle Cure for Fussy Benelli .22's!

Post by Gwhite »

I sent a note to my contact at the factory, and asked about the feeding issues we have had with some pistol/magazine combinations. No real info on that, but 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.
-TT-
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Re: Miracle Cure for Fussy Benelli .22's!

Post by -TT- »

Gwhite wrote: Wed Apr 10, 2024 1:40 pm... 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.
My MP90S was bought in 2016 (date code = "CP" same year), it had very little radius and no visible ramp. I had the same issue with "dinging" the nose and my gunsmith throated the entry by adding a slight radius all around with a felt bob, it has nearly eliminated the issue. And there have been no light strikes or other side effects, and no long pins.

So I'm confused - was this change reverted post-2009?
Gwhite
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Re: Miracle Cure for Fussy Benelli .22's!

Post by Gwhite »

All I know is what the guy at the factory told me. I don't know if he's terribly busy or what, but the answers I get to questions are usually very terse and a bit cryptic. We have very early MP90S's with a definite 2-step bevel on the chamber edge, and they have always worked fine with the old (short) firing pins. The five MP90S's we got in the early 2000's had no visible bevel/radius at all, and they shave lead badly. I suspect they skipped a step in manufacturing as opposed to eliminating it as an intentional design change. I've been carefully stoning a radius on the top & bottom chamber edge on those pistols to try to improve feeding and get rid of the lead shaving. Here are photos of those three flavors:
Chamber Edge Composite.jpg
The longer firing pins are 0.008" longer than the old ones, which is substantial. If they did it to make up for an increased radius on the chamber, the radius would have to be very significant. One of the reasons it's hard to get Benelli .22's at all is they are still making them with 1990 machining techniques. That means little to no CNC, and lots of manual operations. According to Larry Carter, they made small batches about once a year. I suspect that may still be true.

One thing we've found over time is that fussier pistols will often work better with RWS Target Rifle ammo than with CCI or Aguila. I always thought is was due to the recoil characteristics. Recently, I was chasing some feeding issues, and I took a look at the bullet shapes, which are quite different:
Ammo Bullet Shapes.jpg
The shoulder between the driving band and the ogive on Aguila is fairly abrupt. CCI is a little less so, and the longer bullet tip may help to guide the rounds into the chamber better. The RWS has almost no shoulder at all. RWS Target Rifle was costing us ~ $1,000 a case (when we could find it), and apparently it is no longer being imported to the USA. However, Norma TAC-22 is supposedly equivalent. It has the same bullet shape, and it costs ~ $350 a case, which is only slightly more than we pay for CCI. Depending on what remaining issues we find now that the firing pins aren't a problem (I hope), we may lay in a stock of Norma ammo & see if that helps.
-TT-
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Re: Miracle Cure for Fussy Benelli .22's!

Post by -TT- »

Thanks for the comparison pics. Mine (SN starting with 115...) most closely resembles the first, "beveled", and the rim is even all-around with no ramp or obvious relief.

I shoot SK Pistol Match almost exclusively in it. Before the polishing work, rounds would frequently shave lead or jam on entry. Now, rounds will occasionally show a small upper contact ding after being chambered, but they no longer jam, no lead shavings appear, and they all go through the same hole at 50 feet. Shrug.

OBTW Norma TAC22 does shoot well in mine however that ammo positively drips lubricant out of the box. It made a sticky mess of things around the chamber, to say nothing of the magazine and my fingers. The good news is it wipes off easily, which I pretty much had to do to use it tolerably.
Gwhite
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Re: Miracle Cure for Fussy Benelli .22's!

Post by Gwhite »

There are two flavors of TAC-22. The lube on the older black box stuff was very messy. The red box stuff is cleaner, but still not as nice to handle as Aguila. CCI is OK, but the amount of hard wax they put on the bullets can vary wildly from box to box. I've had boxes where adjacent bullets were fused together with wax.

TAC-22 is the only ammo I've found that my Morini free pistol can shoot without having to clean the chamber half way through a match. I don't think the powder burns that much cleaner, but the lube keeps crud from building up in the chamber.

If you don't like grease, stay away from Russian ammo. The stuff was horrible. I still have a few boxes that I should burn up, but I hate shooting it.
cgpro856@aol.com
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Re: Miracle Cure for Fussy Benelli .22's!

Post by cgpro856@aol.com »

My MP90S has been flawless for the 18 years I have owned it. The firing pin broke tonight and I am disappointed to see that they are not easy to find. can anyone tell me where I can get one?
Chris P.
Gwhite
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Re: Miracle Cure for Fussy Benelli .22's!

Post by Gwhite »

I know of a couple sources. Check your PM's.
sthlm
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Re: Miracle Cure for Fussy Benelli .22's!

Post by sthlm »

I own a Mp95 stamped 1994. I had the same issue when the firing pin had broke and i bought a new one. Had similar feeding problems and was told buy one of the leading experts on Benellis in Sweden to shorten the firing pin to a maximum lenght of 32,25 mm or less and it has since worked perfectly. Guess it was a bit longer than the above mentioned but it has worked for me so i guess its a trial and error thing.
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deadeyedick
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Re: Miracle Cure for Fussy Benelli .22's!

Post by deadeyedick »

I resolved my feeding problems by changing the slide return spring from the original which uses 0.6 mm.wire to one made from 0.8 diameter wire.
Amazing transformation.
Gwhite
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Re: Miracle Cure for Fussy Benelli .22's!

Post by Gwhite »

Spring force increases by the FORTH power of the wire diameter. If your wire diameter numbers are correct, that means your new spring is over 3 times stronger than before. I'm amazed it works at all unless you are shooting hot ammo.

Because the force is so sensitive to the wire diameter, it is really important to measure it accurately. A simple caliper measurement won't do it. I use a drill bit shank that is a snug fit inside the spring, and then measure the OD of the spring with a digital micrometer. Measure the drill shank, subtract that & divide by two. That will give you very precise results. Just the normal manufacturing tolerances on the wire OD is enough make a significant difference.

I have a spreadsheet database of about 30 Benelli recoil springs that calculates the open & closed bolt forces. The smallest wire I have ever measured was 0.650 mm, and the largest was 0.723 mm. That alone gives a 50% increase in force. Based on the serial numbers, I can only guess at the vintage of the springs installed in pistols. I have one MP90S of my own that I know the history of, and I also have new factory springs purchased over time. Based on all that, the factory has been slowly increasing the stiffness of the springs over the last 30 years. The latest ones I bought run around 0.72 mm. I do know that my two personal MP90S's like the newer springs.

Using relatively mild ammo (Aguila standard velocity), I have had some cycling issues with the stiffer new springs. However, that may have been before I pinned down a couple of other issues (like carbon fused in the chamber and the long firing pin problem), so it's not clear if the springs were a real issue.

The only problem I've found that was definitely a recoil spring problem was a pistol that would need cleaning every 150 rounds or so. It got filled with carbon very quickly. I took it apart, and discovered that someone had concluded it would be good to cut 6 mm off the length of the spring. That was clearly affecting the combustion of the powder. I put in a new one, and it started behaving like all the others. I once torture tested one of my Benellis after making a number of improvements, including a new stiffer recoil spring. It went about 1100 rounds before it started malfunctioning & needed a bath.

You can definitely feel the increase in force if you use the stiffer springs. The college team I help coach has had a number of small women over the years, and some of them have trouble working the bolt on the Benellis. If they are struggling, we switch them to Walther GSP's or Pardinis.
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deadeyedick
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Re: Miracle Cure for Fussy Benelli .22's!

Post by deadeyedick »

I found that using the standard spring ( 0.6 mm. ) the pistol would not correctly feed, and even damage the brass and lead resulting in an unwanted malfunction.
Buying new replacement springs improved the situation however it would still have the same problem with approximately one in twenty shots.
It however would cycle perfectly using CCI quiet semi auto 835 fps without any hint of a problem.
I then replaced the new Benelli 0.6 spring with one from the .32 which uses 0.8 mm wire and 55 coils.
Not a trace of a problem using CCI standard 1070 fps as was the case with the factory 0.6 spring.
Gwhite
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Re: Miracle Cure for Fussy Benelli .22's!

Post by Gwhite »

The .32 spring is a whole different animal. Just listing the change in wire size is meaningless when everything else has changed as well.

I've never seen serious feeding issues caused by weak springs, but anything is possible. Now that I've stopped chasing problems caused by the long firing pins, I'm focusing on magazine issues, which can cause the sort of feeding problems you describe. We have about 50 magazines for 21 pistols, and normally just mix & match until we find a magazine that works well in a given pistol. I'm now trying to be a bit more scientific about it. I've built a fixture that allows me to measure the height of the bullets relative to the location of the magazine catch slot.

I have discovered that Benelli has made some subtle changes to the followers ("cartridge supports") over time. I think that may improve the consistency of the bullet height, which tends to vary significantly depending on how many rounds are in the magazine. The 1st round tends to sit as much as a millimeter lower than the last couple ones. I'll post more details once I've done additional measurements & tests.
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deadeyedick
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Re: Miracle Cure for Fussy Benelli .22's!

Post by deadeyedick »

The .32 srs is the same length and diameter as the .22 srs. 100 mm. and 5.2 in diameter with the exception that the wire diameter is 0.8 mm.
I ordered a length of 0.8 mm x 5.2 from China, cut 55 coils and installed it. Not a hint of a problem in 500 rounds
Sometimes problems can be more simple than originally thought. At least it was with me.
Gwhite
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Re: Miracle Cure for Fussy Benelli .22's!

Post by Gwhite »

Most of the .22 springs I've measured are at least 110 mm. The average is around 115 mm. If your .22 spring was only 100 mm, that's a problem right there.

Given the range of spring parameters I've seen from pistols that worked just fine, they aren't very fussy. That's why I'm surprised you had issues to begin with. Even the spring that was cut down by 6mm cycled & fed OK, it just fouled horribly.
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deadeyedick
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Re: Miracle Cure for Fussy Benelli .22's!

Post by deadeyedick »

The .32 spring length I mentioned was from a well used spring that had shortened to 100 mm after repeated use.
However I used the same number of coils from the new spring and it was obviously longer. However the result was the same.
I purchased the pistol new in 2012 and had similar intermittent problems from new. Others seem to have no trouble.
I forgot to mention that I have also recently increased the magazine spring length which I believe has also been helpful.
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