Is CM84 ammo sensitive?

[TomAmlie]

Hi. I just received my new-to-me/used Morini CM84. I absolutely LOVE the balance, sights, and trigger.

I took it to the range this morning for the first time, and was disappointed. The first 5 or 6 shots to zero the gun were a joy. After that, every second or third "shot" was a light-strike that failed to fire. After 5 non-fires in 14 rounds I called it quits. This is some Federal Target ammunition that my Hammerli 160 and Pardini PGP75 digest with no problem at all, as does my Walther KKM. I haven't had a chance to try the gun with different ammunition yet (I've got some Aguila and some Wolf at home), but I'm wondering if I would be premature in being worried.

As an aside, the "light strike non-fires" failed to eject when I opened the chamber. I had to use a piece of plastic rod to poke them out.

Has anyone else experienced the CM84 being funtionally sensitive to the ammunition used?

Thanks.

[Fred]

Tom,

Before you panic, try a fresh battery.

HTH,
FredB

[Steve Swartz]

My 4 year old CM84E has NEVER failed to ignite even the most stubborn 22 ammo (e.g. that Federal Gold Medal Match with the dimple in the butt; CCI, etc.) - as long as

1) the pistol is cocked (sometimes it will "De-Cock" itself when the loading lever is closed) [improper cleaning/reassembly]
2) working batteries are installed [failure to replace batteries annually]
3) direct sunlight is not interfering with the "safety" [sic] photo system [shooting uncovered with sun directly in eyes]
4) condensation/crud has not built up on the contact points [airconditioned car straight to Ft. Benning firing line on 90 degree/90% day]

I need to point out, however, that in each instance 1-4 above each occured only once and were easily prevented with a little awareness and preparation.

All of that having been said, the gun is a whole heck of a lot more reliable, consistent, and easy to shoot than the "Toz Project" I used to own . . .

Steve Swartz

[Mark Briggs]

Just as an aside, I've done ammo testing with my CM84 and a couple of different barrels (original factory part in both cases). My gun ate everything without a hiccup. And it produced very reasonable groups even when fed some "cheap" ammo like T22's and Remington Target. Altogether I tested about two dozen different ammo types, including cheap stuff and expensive stuff, right up to Lapua Midas, and even some really weird stuff like Russian Junior ammo, Sellier and Ballot, Aguilla, as well as more common stuff like PMC, Federal, CCI, Remington, Winchester, Eley and RWS. It all worked perfectly.

Steve brought up the idea of the gun not being cocked as a cause of misfires. This is reasonably common with "new operators". When you eject the spent cartridge the cocking lever has to come all the way to the top of its travel or the gun will not cock. I've done this to myself a couple of times.

On the topic of not ejecting, your experience leads me to believe there are a couple of potential problems.

1) dirty chamber, including the groove in which the rim of the case rides
2) an overly-wide extractor groove in the barrel

Number 1 can be fixed with a thorough cleaning.
Number 2 can be fixed with the strategic use of thin washers as shims on the pin which acts as the hinge point for the extractor/ejector. This isn't a frequently-encountered problem.

[TomAmlie]

Steve -

Thanks for the response. Let me clarify/restate and see what your thoughts are:

1. Gun de-cocking: When I release the "shot" the feel/sound is much different than when dry-firing. I assume I'm feeling/hearing the firing pin striking. There are very faint firing pin dimples on the failed-to-fire cartridge cases. Also, on each fail-to-fire I recocked the gun and re-tried at least twice, with no improvement. I also saw some very slight movement in the breech-opening-lever when the shot should have discharged, which I assume was the reaction to the force of the firing pin releasing.

Items 2, 3, and 4 on your list would seem to manifest themselves by the trigger being "dead" and not responding to my trigger pull. Again, I can feel and hear the trigger mechanism "clicking" with each pull of the trigger. I would assume a dead or weak battery would result in the firing pin not releasing at all. The problem seems to be a weak thrust of the firing pin, which I assume is not a function of battery power (unless the firing pin is actually propelled by electricity?).

How does the failure to eject the non-fired cartridges figure into this?

Thanks again,
Tom

[Mark Briggs]

Tom - faint dimples from the firing pin can be caused by several problems, none of them electrical.

1) busted firing pin - look at the end - it sound be rounded off to literally make a round dimple in the cartridge

2) DIRT - every time a shot is fired some gunk blows back through the same hole in the breechblock that is used by the firing pin. This gunk builds up in front of the main body portion of the firing pin and can limit its forward travel. This, frankly, would be my #1 suspect.

3) weak mainspring. You should have a spare spring anyhow, so buy a new one now and give it a try. If somebody left the gun cocked for ages and ages it might have weakened the spring. A new spring isn't that much money, so it's a cheap troubleshooting step.

4) dirt in the groove in which the rim of the cartridge sits. An accumulation of dirt under the rim of the cartridge can effectively absorb a good chunk of the impact force imparted by the firing pin, resulting in mis-fires. A dental pick or similar device is your best friend when it comes to cleaning out this recess in the breech face.

In general, you should take the gun apart, strip it as far as you can, and clean everything, then lube it with light oil and reassemble. You might be surprised how much stuff is inside the gun, binding up things that should normally move freely. A fellow shooter in our region owned his CM84 for two years and didn't know how to disassemble it, so it had never been cleaned. I'm afraid this kind of story isn't terribly uncommon, so your gun may have accumulated enough dirt inside to have a negative impact on operation.

Good luck in making it work. The CM84 is a fine pistol!

[Fred]

I would assume a dead or weak battery would result in the firing pin not releasing at all. The problem seems to be a weak thrust of the firing pin, which I assume is not a function of battery power (unless the firing pin is actually propelled by electricity?).

How does the failure to eject the non-fired cartridges figure into this?

Thanks again,
Tom

1. Perhaps your gun is different, but with my 84e, a weak battery WILL give weak firing pin hits. That's how I know when to change the battery.

2. The 84e extractor by design has little contact with the shell rim and weak leverage, compared to, for example, the TOZ extractor. Every 84e that I have seen (about 5-6) has had trouble extracting tightly chambered unfired rounds.

I'm still betting that nothing is wrong with your gun except a weak battery. When you hear hoofbeats, don't think zebras.

FredB

[ded]

i agree 100% with fred and may i add i recived my first brick of lapua master l this week. I thought eley eps was good, this is better( for me any way)

[PaulT]

Firstly, for the strip-down; Mark Briggs prepared and posted on this forum an excellent and detailed strip-down of the 84e including the firing pin in breach block. Print this out and in conjunction with the exploded parts manual for the reference of part numbers (manuals on Morini web site in cease your unit did not have this) you should have no problems.

With a good clean and removal of build-up in breach block, you should have no feeding problems.

As posted before, several of us have observed any Lapua batch (Pistol King/Master/Midas) is highly likely to provide a very good group, approaching X ring, batch testing Lapua will obviously improve this. Eley Tenex is superb but requires batch testing for reliable good factory test results. Experience has focused on these two brands.

From your posts, it sounds like removal of build-up or a main spring issue. The strip-down will confirm the integrity of the firing pin.

If your new pistol has a compensator, make sure that this is well cleaned; again, this forum has a lot of posts re these plus their cleaning.

Stating the obvious, if you have access to a test rig, that will provide confirmation of ammunition combination and give your proof positive a reminder of how accurate the pistol really is.

Hope you get over these teething problems and enjoy shooting your new pistol!

[Nev C]

I have a C84ME and right from the first shot it has had trouble ejecting spent rounds, I normally use SK Pistol match but the CM84ME just will not eject them most of the time. I have not found a brand of .22 yet that will eject 100% of the time. And yes, I do keep the pistol cleaned, if anyone knows of a brand of .22 that ejects 100% of the time please let me know.

[Ernie Rodriguez]

Some CM84E pistols do have tighter chambers than others-for sure. I went through the same thing.I found Federal 711b and SK ammo reg and Pistol match to be OK. By OK I mean insertion of cartridge and ejection of same. There will be a point that ejection becomes problematic due to a dirty chamber-and that is the point a non-metalic brush should be used to clean out the chamber until the next 30/40 rounds.You will have to find a brand for your pistol-but I don't think a brand exists that you can run through 50 to 75 shots,in a tight chamber,and have no ejection problems what so ever.Ernie