I have a MGC ABS XM177E2 (M16A1 Commando) that is firing quite well on FULL and SEMI. I am currently really enjoying this model but realized that some carts got damaged badly/destroyed. The threads got blowed off and the upper part of the cart gets widened.
Does anyone know what the issue may be? Maybe the piston travels not easy enough, but I do lightly grease the carts inside ...
Will have to look for some replacement carts anyway ...
Wow those cartridges are taking a real beating aren't they
I've only seen similar damage on old cartridges that have been used over and over again. Repeated firing can cause the screw-on top to spread and threads to fail but those in your photo look almost like they've been squashed. There's a definate bulge all around the threaded area.
Is it possible that the detonator chamber or the det. pin is positioned too close to the bolt face What I mean is could the cartridge be squashed between the bolt-face and the bottom of the chamber
How many cartridges have failed like this
_________________ Cerwyn
Hobby collector of Replica model guns and Militaria. also member of Living History Reenactment Groups.
I wouldn't expect any cartridge to wear out that badly after only 10-15 shots 'Mike.
Are there any signs of damage at either end i.e. cartridge base and neck
The old cartridges I've seen in the past, having been fired many, many times, show a gradual spreading around the threaded base of the cartridge "top" leading to loss of gas pressure and poor firing. Your photo looks almost like the cartridge has been stood on end on a solid surface and hit hard by a heavy hammer
I've seen Marushin 9mm and MGC 220s break at the threads but only because they'd been damaged by a "stove-pipe" jam. They were impossible to unscrew by hand and broke when more force was applied in a vice...
How many caps do you load into these cartridges Is it just 1 x 7mm cap or are you using 1x 7mm and 1 x 5mm
_________________ Cerwyn
Hobby collector of Replica model guns and Militaria. also member of Living History Reenactment Groups.
Of course it is only one 7 mm cap . The MGC Cap Piston design is a good design and seals the hot gases well. One cap is powerful enough. I do not see what caused the trouble. The gun is operating fine. Anyway I used these carts with another MGC M16 I do not longer have. Maybe this gun caused the damage. I will have to test some new carts and see if they get damaged too.
Of course it is only one 7 mm cap . The MGC Cap Piston design is a good design and seals the hot gases well. One cap is powerful enough. I do not see what caused the trouble. The gun is operating fine. Anyway I used these carts with another MGC M16 I do not longer have. Maybe this gun caused the damage. I will have to test some new carts and see if they get damaged too.
The use of 2 caps can blow cartridges apart but as you rightly say, the MGC c.p. design only needs a single cap. If you've used these cartridges before, how old are they 'Mike You don't suppose the brass material has got brittle with age do you Having said that, the majority of my cartridges are over 3 years old (some 5 yrs) but I've only seen 2 break during firing, a few others due to "stove-pipe" damage.
_________________ Cerwyn
Hobby collector of Replica model guns and Militaria. also member of Living History Reenactment Groups.
Subject: MGC HW CP carts getting damaged 
Wed Aug 12, 2009 9:07 pm
What I mean is could the cartridge be squashed between the bolt-face and the bottom of the chamber 
. The MGC Cap Piston design is a good design and seals the hot gases well. One cap is powerful enough. I do not see what caused the trouble. The gun is operating fine. Anyway I used these carts with another MGC M16 I do not longer have. Maybe this gun caused the damage. I will have to test some new carts and see if they get damaged too.
