MGC MP40 Problems

Post by jayrbenz

I just picked up my first MGC MP40 model gun. The problem is the barrel won't stay on. I've attached a pic of the barrel nut. Does it look like an MGC unit? The threads on the receiver look good so I don't think it's stripped out. Also, the bolt won't lock in to the cutout at the rear position. Is this common?

Thanks all,
Jayrbenz

P.S. It's also missing the little rear flip sight. Are these available anywhere?


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Post by Mark

Hi Jay,

The barrel nut that you have is a Marushin unit by the looks of it. The tread form is correct, but the Marushin barrel nut is far too deep and the "split washer" assembly is too short to take up the extra depth. The MGC original barrel nut was styled incorrectly and looks funny so, many people replace the nut with the Marushin nut assy. (My MGC MP has a custom machined two flat nut) The only way to "fix" the problem is to either replace the barrel nut with a MGC original or shim out the split nut assembly to take up the extra depth. It also looks like you are missing the plastic, snap on barrel rest. Now, as for the bolt handle not going into the rear safety cutout, it is a common "problem" with these models. What the "problem" is, is that the telescoping tube assy has not been pushed into the bolt as far as it can go after it was last disassembled. When this happens, the telescoping tube assy sticks out too far for the bolt to travel all the way back to the safety notch as it bottoms out. I usually try to push/twist the telescoping tube assy further into the bolt assy. That usually fixes the problem. As for the rear sight leaf, I don't think that any are out there except for a custom built replacement.
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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

Post by jayrbenz

Thanks for the info Mark,
Do you have any pics of the shim I need to make? Does it actually move the trunion out? I think I'm missing something, the barrel nut won't even catch the threads on the trunion. Would it be easier just to find an MGC barrel nut?

Thanks again Mark,
Jay

Post by Doc

Jay, what you have is an early Marushin Barrel nut ,(from the all zinc MP40s) the threads on this are wider and more fine than the MGC Trunnion.
Mark is talking about the Later ABS MP40 Barrel nut as having the correct threads but needs shiming to work.
Only place I am aware that has MGC MP40 spares is modelguncollector in the UK .

However a cheaper option will be to get a newer Marushin MP40 nut (From Francky) and shim it out

DOC
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Post by jayrbenz

Thanks Doc,
Do you think anyone would want to trade my early Marushin part for one that would work with my MGC or are the early Marushin barrel nuts pretty common?
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