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Discussion Starter #1
Hello recently got a PS90 it puts a scratch through the coating and and a little bit in to the brass as they feed from mag to chamber. Wanting to reload is there a fix for this seems to do it on two different mags.



Here is a pic same spot every time brass hits the chamber as it feeds from mag. Maybe that is just normal?

Jason
 

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NEW gun ?
This I have not seen before, there is definitely an issue. Do you have mags that it doesn't do it when using ?
 

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No not normal answer these questions,

New or used purchase?
Did you clean before using?
What ammo did you shoot?
What brand of mags did you use?
 

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Discussion Starter #5
Bought used but it was new only a few rounds fired through it. It is the newest one with rail on top standard think it is called. Shoots great just damaged brass. Did clean. Came with one mag bought two others all are FN mags. American eagle ammo. Seems to do it as thy feed in can run unfired rounds with charging Handel and still have spot on them looks like looking through the bottom as they feed they hit the chamber pretty hard.

Jason
 

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My first thought is to remove the upper and inspect the chamber for any debris or manufacture defects.

You said in your last "they hit the chamber pretty hard". Do you mean they are not lined up to the chamber correctly or the spring is strong?

The other thing I'm wondering about is the moving parts group. Have the moving parts group forward (breach closed) and insert a full mag on the weapon. Pull the charging handle back and lock the moving parts group to the rear using the dust cover in the ejection port. Remove the magazine. Any sign of damage on the first round in the magazine? If so check the top of the moving parts group for anything that could be doing this.

If not then what I would do is try to find out when this is happening. Load round into chamber and eject it with out fireing. Is it damaged?

Where are your ejected rounds going? Gravel, carpet, brass catcher ...

I know you said you want to reload so you probably know your stuff and all ready checked what I posted. Just covering everything.
 

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Discussion Starter #7 (Edited)
Looks to be happening as the round comes out of mag as it hits the bottom edge of chamber. Then pushed up and chambers fine. Will do a little more reasurch in the morning.

Yes as stated above the damage still happens just cycling rounds and not firing them.

Jason
 

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Bizarre.. looks like somethign is stuck or wrong with the chamber.

Chamber a round without firing, and eject it manually, to see what happens.
 

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I can assume that you have 1 mag that when used doesn't damage the cases ? That almost rules out the weapon.
 

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Discussion Starter #11
Ok after finding out this was not normal. I cleaned it up and fired a couple rounds this morning. Think I may have located the problem.









Next question the round pice looks to be hitting the shell is that sopose to be there. Has a ruff spot on it too. Could polish it up I am sure but don't want to mess any thing up.

Jason
 

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Jason...the moment you take a file to smooth that part, you will have voided the warranty. Seems like you've identified where the problem is occurring, so I'd contact FN and have them fix it for you.
 

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that's the ejector retaining pin. Looks like it's either too long or didn't get driven in all the way. you should be able to get a new one fairly easily.
 

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Discussion Starter #14
Ok thanks will do a little more poking around and decide if it goes back to FN or I will just take a 1000 grit diamond stone and then a fine ceramic stone and polish it up. Thanks for playing along on this one. I am the second owner so I don't now if it is under warranty.


Jason
 

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I might try driving that pin flush before I start grinding or sanding anything - Just a suggestion otherwise you are probably just shortening the roll pin and you can buy another if you really need to.
 

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I don't think he would be able to drive the pin in further, as it looks peened over.
 

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ok so the roll pin that retains the ejector is not blind pinned it is accessible through the opposing side of the bolt it can be reverse driven out with a roll pin punch and replaced with a new $5 pin from MGW FNH PS 90 Spring-Type Straight Pin, Coiled, Heavy Duty I do not recommend any home dremmelling or anything other than replacing a pin that was improperly installed. I have replaced all the parts in a bolt due to a over-pressurized cartridge causing catastrophic damage to the ejector, extractor, springs and the stock. This is just my advice from the gunsmithing I have done on this platform. (a word of caution if you do decide to remove the roll pin use caution as the ejector spring has alot of pressure and you may be looking for parts that fly across the room. :) just my 2 cents
 

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Can I add .02 ?
I would get a pin punch set set, drive the roll pin out from behind, the (non peened over side ), replace, shorten, grind, file, whatever... the original too long pin and tap it back in (after it has been adjusted ) below the surface.
I would want to add , buying a spare is a good idea, a general mechanical / understanding is needed.
ALSO... sometimes " factory " pins are unusually tight, or at ;least I have found. For example the tapered dowel pins that hold the front site / gas block ( A2 style ) of an M16/AR15.... those buggers give me big ones, and I have been pounding out dowels for way longer than I would care to think about.
Just a word of caution, I don't see this as a difficult project, a little common sense, and a good set of gunsmithing punches would be needed, a BOX to catch flying parts, some oil perhaps, and some common mechanical abilities.
Good Luck !
mjk1
 

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Discussion Starter #20 (Edited)
Thanks for the help got pin where I could take the part sticking up off with a flat 1000 grit diamond stone. Then polished it slick wit a ceramic stone. Put back in add it is smooth running great and no more damaged brass.





Jason
 
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