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 Restoring Old Cartridges

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Cerwyn
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PostSubject: Restoring Old Cartridges   Thu Aug 14, 2008 10:32 am

Moved from "O" Ring Disussions...

Dartec wrote:
Yep I'm up for a group buy of any lube that is right for the job and imo rancky and the guys in Japan should know as they make the modelguns.
Anybody suggestions for smarting the cartridges up ie the burrs, scuffs and battering the rims get?
Is a file a good idea or would that change the dimensions too much, may be emery paper or something?
Hi Dartec,
Wire wool will take off slight burring, brass cases are pretty soft so they don't take much work.
Small files, Halfords do a set of 3, one's flat, one's triangular for cleaning up screw threads and the set's got a round file too.
Used carefully, these are fine enough to clean up without removing too much material, but take your time and just do a little at a time.
Dents in the rims are a bit more awkward though. I'm finding problems getting some of my .45cal ones to eject from my MGC Thompson if the claw happens to grab a dented portion.
I'm going to try cleaning up with the files gently and see what happens.
Cerwyn
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Cerwyn
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PostSubject: Re: Restoring Old Cartridges   Thu Aug 14, 2008 10:33 am

Post by Mark

Dents on the cartridge rims is problematical as you really can't remove the dents without making the situation worse..

Please, keep the files away from the threads as their thread form is delicate as they are very fine and easily damaged. The best way to clean them is still the baking soda/vingar solution in my opinion....

It's too bad that the manufacturers don't make the cartridges out of "cartridge grade" brass like the major ammunition manufacturers do as the modelgun cartridges would last longer as they would be harder.

I have been thinking that it would be nice to replace the hard steel ejectors with nylon (or some other thermoplastic) so they would not damage the brass as much.

Polishing the cartridges and champhering the case mouths is a good idea as long as the work is done carefully if you have access to a lathe, then the cartridge polishing (internal) is easily done. If a lathe isn't available, a slotted wooden dowel with steel wool can be used with a hand drill.
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Wanted to buy: MGC Sten MK3....trades?(still)

MGC MP40 Marushin MP40 Nakata MP40 TRC MP40

Modelgun manufacturers, past and present:CMC,CAW,Hudson,HWS,LS,MGC(R.I.P. 1960's~2007) Marushin,Marui,Kokusai,Shoei,Tanaka and Western Arms
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Cerwyn
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PostSubject: Re: Restoring Old Cartridges   Thu Aug 14, 2008 10:33 am

Hi again,

Oops! I wasn't suggesting cleaning the threads as, just as you say, they're far too fine.
The file set I'd seen had a little thread cleaning file in the pouch which could be used on smaller flat surfaces.
I don't have access to lathes anymore, more's the pity!)I'd thought of using doweling and steel wool but turning by hand rather than a drill as my cartridges aren't that badly pitted internally.
Would a nylon or plastic claw stand up to the rigours of being rammed up against cartridges do you think? One problem we have, I suppose, is that most guns, especially military SMG's and the like wouldn't be using reloaded ammo so dents and rough edged rims wouldn't have been a problem. Shouldn't think combat troops spent much time searching for spent cases eh?
How long a life would you think a PFC cartridge has given average use?
Dented rims are a problem, wouldn't it render a cartridge useless after a while?
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PostSubject: Re: Restoring Old Cartridges   Thu Aug 14, 2008 10:34 am

Post by Mark

I really don't know just what the service life of a modelgun cartridge is. Given the proper care, a cartridge might shoot over 500 (or so) cap loads before the cartridge rim is too badly beaten up to use. I guess the question needs to be answered with experimentation by one of us..

The nylon ejector would have to be replaced every few hundred rounds i think as they would wear after repeated battering by the cartridges. Now, a nylon extractor would not stand up to the abuse so, i really don't suggest replacing them with plastic. besides, the extractors really don't damage the cartridge cases rim like the ejector does.
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Wanted to buy: MGC Sten MK3....trades?(still)

MGC MP40 Marushin MP40 Nakata MP40 TRC MP40

Modelgun manufacturers, past and present:CMC,CAW,Hudson,HWS,LS,MGC(R.I.P. 1960's~2007) Marushin,Marui,Kokusai,Shoei,Tanaka and Western Arms
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PostSubject: Re: Restoring Old Cartridges   Thu Aug 14, 2008 10:34 am

500 or so isn't bad then is it! Being new to modelguns like this I was expecting you to suggest far fewer!
It'll be interesting to see how nylon copes as per your idea.
I first 'found' this forum when trying to sort out problems with the ABS receiver / firing chamber in my Marushin MP40. It seems that Japanese legislation insists (now anyway) on soft materials like ABS being used to stop people converting their models to fire real ammo. Trouble is, it marks up quickly with lots of use.
Somebody, was it you by any chance?, was making stainless receiver / firing chambers for the MP40's

I find this forum fascinating, so many ideas and help out there!

Cerwyn
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PostSubject: Re: Restoring Old Cartridges   Thu Aug 14, 2008 10:35 am

Post by Dartec

Perhaps something liek a jewelers file set or watch makers as these wound be very fine.

May be a quick rub with emery paper every use could prolong the burring/scuffing of the cartridge rims. My logic is once it happens then it gets worse bit like pulling a thread once it starts then it just goes on and on.

500 caps per cartridge sound not too bad. So if we replace our cartridges once per year, then total running cost are around 53 pence per cartridge.

Which isn't too bad as the real thing is around 28+pence per round. If I have my sums right.
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PostSubject: Re: Restoring Old Cartridges   Thu Aug 14, 2008 10:35 am

Quote :
Somebody, was it you by any chance?, was making stainless receiver / firing chambers for the MP40's
cerwyn, i make the stainless steel Marushin MP40 chambers although, they are difficult to make...
IF the cartridges last for 500 caps, they will be very beat up!!! Actually, the "primers" anvil sometimes mushrooms due to being hit with the firing pin. Also, the "piston" (as well as the O-rings in the CP style) will tend to get a little shorter and misfires will increase..Again, someone should experiment and see just how many caps a given cartridge will take..
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PostSubject: Re: Restoring Old Cartridges   Thu Aug 14, 2008 10:36 am

Just like your 'pulling thread' logic, once you start removing brass you can't put it back.
Everything wears out eventually though. The pressures inside the cartridge when ignited must be pretty high to be strong enough to create enough recoil to send the bolt back each time. And then it gets hit both ends by bolt and pin. Flattening and mushrooming internally is inevitable I suppose.
Long term, cartridge prices work out reasonably well but they're still pretty expensive. Francky1958 got me some Marui carts and caps really cheap, even with shippingfrom Japan.
I've asked him to quote for Marushin and Hudson types now too as it sounds like there's a big saving to be made.

How much do you charge, John, for a steel MP40 receiver / chamber if you sell them on that is?

Cerwyn
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PostSubject: Re: Restoring Old Cartridges   Thu Aug 14, 2008 10:36 am

cerwyn, The stainless steel Marushin MP40 replacement chambers are $75 U.S. when i have them to sell as they are a pain to make..

Yes, cartridges are the major expense along with the caps and the modelguns themselves. I really hate that the cartridges get beat-up when they are "fired" i really don't like to see brand-new cartridges get dents on their rims and scratches/dents on their sides But, as long as there is a good supply of cartridges available into the future i really don't have too much of a problem with the cartridges wearing out...
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Wanted to buy: MGC Sten MK3....trades?(still)

MGC MP40 Marushin MP40 Nakata MP40 TRC MP40

Modelgun manufacturers, past and present:CMC,CAW,Hudson,HWS,LS,MGC(R.I.P. 1960's~2007) Marushin,Marui,Kokusai,Shoei,Tanaka and Western Arms
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PostSubject: Re: Restoring Old Cartridges   Thu Aug 14, 2008 10:44 am

Post by Mark

I forgot to mention, the thickness of the cartridge "case" or body also determines the cartridges life cycle as the thinner cartridges have to deal with the higer pressures and they tend to stretch over time. The MGC M16 CP cartridges are really thin and the threads are near the center of the cartridge these cartridges really don't look like they will last a long time. (especially if the cartridges aren't "tight" before they are "fired")
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MGC MP40 Marushin MP40 Nakata MP40 TRC MP40

Modelgun manufacturers, past and present:CMC,CAW,Hudson,HWS,LS,MGC(R.I.P. 1960's~2007) Marushin,Marui,Kokusai,Shoei,Tanaka and Western Arms
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