Cartridge Assembly Problems

Post by rizzo

The 'valve' in my MGC 1911 cartridges have become increasingly difficult to put into the main cartridge housing... It is not to do with the O ring as when i take the O ring off, i still cannot get the metal part of the valve into the cartridge- so either the inner casing of the cartridge has shrunk or the valve has expanded I have cleaned the cartridges thoroughly. Now i can only get the valve in by hammering, which isn't desirable... any ideas?

That is interesting rizzo, i have sometimes encountered this problem with the "valve" (the piston) not fitting inside the case. we have to remember that the cartridges take quite a beating as they hit walls,lamps,cabinets,cats,dogs,sinks etc. when the are ejected.

Sometimes the cartridge case can distort enough to cause a "sticky" piston bore that is why when you are shooting the modelguns in an enclosed space like your living room,kitchen etc. you need to have some sort of a cartridge catcher system or something soft to hit to prevent cartridge damage.

What is interesting to me is that the cartridges in some cases expand and the piston with the O-ring is usually loose in the case. Thankfully, this condition is rare and most of the cartridges are thick enough to handle the high pressures and prevent the cases expansion.

I try to ensure that the cartridges don't hit anything hard (or breakable) other than the carpet.

As for fixing the cartridges, be aware that the pistons are sometimes fitted to their individual case and it's not always a good idea to mix the pistons from different manufactures like Hudson pistons in MGC cartridges however, it can be done.

The case can be either drilled(not really recomended) swaged or reamed back into shape with the proper tools.
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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

Post by rizzo

Yes, i think i shall have to procure a dremel or something, it just seems very strange that they should ALL do this so suddenly

Post by Mark

rizzo, before you take the Dermel to the cases,Please be sure to check all of your cartridges very closely and try all of the pistons in each case mouth to see if they fit any better. I would hate to see any of the cartridges go to waste although, i know that you would be careful to avoid damaging them. If you do get a Dermel, use the buffing wheel and try that and polish the insides of the case. If all of the cartridges (how many of them do you have?) have gone bad at once perhaps that is caused by chemical build up or corrosion (brass tarnish) as the clearances that MGC and others use is fairly tight, these clearances can be taken up by very small changes heat, cold, tarnish etc.
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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

Post by Mark

Quote :

No worries, the shop i bought them from has offered to take them back and if they cannot fix them are sending out some new ones free of charge

Hey that's awesome! I however don't have that option here in the U.S. so, i have to fix things my self...

Post by Claymore

That's good that they will change them. i have noticed that the pistons can be troublsome to get back in after they have been fired a few times but once cleaned and cooled down seem OK again.

My rounds for the MGC M4A1 however seem to flared around the base of the top part of the round. it looks like it has been hit with force (which of course it has) and caused the top part to flare out against the bottom part.

Strange that that should happen unless there is a problem with the space where the barrel pin is.

Post by Mark

claymore, my MGC M16/725/M4 cartridges are in the same condition. I think that the flaring is caused by the loading forces into the chamber as the cartridges tend to "bend" at the seam when the bolt hits them. The "problem" might be caused by leaving the cartridges slightly loose after assembling them.

You might want to tighten the cartridges up a little more before firing them as i have noticed that some of the cartridges loosen up as you insert them into the magazine.
_________________
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

Post by Claymore

yeah i have noticed that they loosen up, normally i will tighten them if they are real bad, i will tighten them as hard as i can from now on. I did think it would be the force of the action doing it, it looked that kind of damage.
Do you get problems with your rounds when this happens or are they OK. By the way now have some silicone grease for the pistons, so will let you know how well it works.

Post by Mark

Yes, i do have some evident damage to the cartridges due to the cartridge looseness mostly the flaring that you noted earlier.

I always seem to notice the looseness of the cartridges during loading the magazines and when i detect it i remove the cartridge in question and hand tighten it.

I will interested in the results of your silicone grease test i am sure that it will help.
_________________
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