Morini CM 84E Chamber Wall & Extractor Damage

[CA Bullseye]

This posting goes out to Francesco Repich, Mark Briggs, Steve Swartz, and all those who wish to chime in.

While cleaning my Morini I discovered a nick on the right side of the chamber opening wall, and wear on the left side of the extractor ( Fig 1, 2). Is this nick something to be concerned about? Should it be repaired, what is the process to repair it? Does it have any long-term effect if un-repaired?

Let me add that I do not notice a problem with the operation of the firearm. I am very happy with it. For the most part spent case extraction has been good. I’ve been using Eley Practice (white box) and have had no problems. But I recently switched to Eley Pistol Target (yellow box) and have had one or two cases out of 50 rounds that stick and do not eject.

I’m sure you’ll agree that this is due to discharging the firing pin on an empty. I’ll be the first to admit that I have done this. But I’ll also add that this was done inadvertently and was done less then a dozen times. I took delivery of my Morini CM84E in July 2005 and I posted a question regarding the correct way to dry fire ( http://www.targettalk.org/viewtopic.php ... &highlight ) and have been following this process since.

Another thing that I noticed was on the spent case (Fig 3 – 5). Because I noticed the nick on the chamber wall I figured I might find something on the spent case that corresponds to the firing pin (Fig 3), but I didn’t. What I did find worth commenting on was a case bulge at 6 o’clock (Fig 4A & Fig 5A). The black mark is for reference to show the firing pin depression in relationship to the bulge. This bulge is triangle in shape and points towards the opening.

In advance your comments are appreciated.

CA Bullseye

[toznerd]

The sample I have (31XX) looks similar, except the metal is gone, leaving a triangle shaped void in the chamber wall. It blows out (not splits but expands) the case when fired. I have fired SK Jagd, ELEY, Aguila, Lapua, and Russian TEMP through it with no problems. The extractor supports the thin chamber wall in that area, so I doubt that the chamber wall in that area will erode any further (as long as current chamber pressures are not exceeded). Cases all eject easily, and as state above, I have not split a case yet. I have not yet had a chance to test fire for groups, so I don't know if it is cause for a concern regarding accuracy. I would assume not. Besides, if 31XX becomes troublesome in any way, I have a superb, mid- 1970s TOZ-35 that functions flawlessly and groups the same.

As for the firing pin strike, it is at c. 1:30 o'clock or 45 degrees from the top, and the missing material near the extractor of my sample begins at c. 3:00 o'clock or about 65 degrees and ends at about 120 degrees clockwise from the top. I don't think striker impacts are the cause. More than likely it is close tolerances and thin material that has been work hardened and breaks away after it loses elasticity. I received my sample as previously owned, so I don't know the complete history, but I always insert a spent hull to drop the striker.

I measured some sample brass: the case expands from a nominal 5.92mm diameter in the unaffected area to 6.00mm, so it is bulging my typical cases about 3/100 of one millimeter at the area of missing chamber wall.

I wonder if the new barrel source addresses resolves this dimension issue, as I think it is not uncommon.

I don't see this as being a problem in my case, pending accuracy tests. Having said that, I am NOT an engineer.

How about you other CM-84 shooters?

toznerd

[j-team]

I've made a few replacement barrels for Morini free pistols in recent years (for people who wanted shorter/ligher pistols) and always thought when machining this extractor slot that is wasn't the best design. Not only does it cause the problem shown above but they usually don't extract properly anyway. Most have to be picked out the last bit by hand (which isn't a complete disaster in FP)

It's probably the only bad feature of an otherwise good design.

[Brian James]

CA Bullseye,

My barrel is almost identical to yours, its circa 2004, and while I was not pleased that it occured it does not adversly affect how the gun performs. The brass expands, but thats not the end of the world.

I have had a shorter barrel made, and it developed the same issue. The design lends itseld to this problem. I did purchase an extra extractor, and filed it so it cut into the brass more in order to make the extraction easier.

Brian

[Mark Briggs]

Welcome to the club. My 84E had this same problem, and the Morini factory, in their customary way, shipped a replacement barrel since the pistol was still under warranty.

Subsequently the replacement barrel also experienced the same problem. Group testing shows no impact on group size with this portion of the chamber wall missing.

I agree with Toznerd that this is a sub-optimal design and could be improved upon. I would suggest making the extractor differently such that it actually becomes the sidewall of the chamber in that very localized area. This would require the barrel to have a notch cut in the same place where the metal is currently breaking through, and of course a matching buildup of metal on the extractor to fill that notch in the chamber wall. Other manufacturers (not necessarily of FP's) have done this with great success.

Also - the 84E's that I've seen all extract and eject fully except when extremely dirty or when extremely cold (-10C or so). If your pistol is not extracting/ejecting reliably it would seem an indication of a very tight chamber. A visit to a good gunsmith who has a match .22 chamber reamer might help with this. Alternatively some lapping of the chamber with emery cloth will also help. (Look for other posts on this board concerning Feinwerkbau AW93 chambers and you'll find posts describing how to lap the chamber with emery cloth.)

Hope this helps. And keep shooting!