MGC detonator pin problem

Hello everyone. Firstly great forum you have here. I'm new to the hobby so it's nice to have so much information in one place but I've got a problem I can't find an answer to.

I recently bought a MGC Sterling but when I unpacked it I found the detonator pin in the breech. I removed the barrel and put it back only for it to fall out again. This is probably because the part has become disassembled but, because of my newness, I don't quite know how to put it back together or even if the entire part is present. I've put a photo of what I have below.

Thank you in advance for any help

Sam

Thanks Cerwyn, all sorted.

My pleasure Sam

If there's anything else we can help you with, please don't hesitate to ask

Ok, no longer fixed. It appears the grub screw isn't exerting enough force on the pin to withstand dry firing at which point the pin is shook loose but the grub screw is still tight so I'm back at square one.

I've also got another problem in that the selector switch is very loose and won't actually select anything. Whilst I know I can strip the grip and tighten everything up thanks to megamicrofish's thread I can't get the screw out as the head is a bit knackered (see pic below). Any ideas how to get this out.

Thank you

Psammead wrote:

I can't get the screw out as the head is a bit knackered (see pic below). Any ideas how to get this out.

With a Dremel ;-)

This is a dummy decoration, not a real screw. Bad move on MGC part, as owners just destroy these screws trying to "undo" them by force.

To remove your grip unscrew the real one that is at the bottom.

Thanks, from the diagram I thought it might be just a bit of decoration but seeing as it was wrecked I figured it must have had some functionality once upon a time. Obviously not...

Hi Sam

Looking at your original photo of the Detonator Pin, could the pin be a Marushin MP40 part it looks very similar apart from the tapered "skirt" mid-way along.
Try measuring the the largest diameter end of the pin, how does it compare to this drg:-

Next, how loose a fit is it in the brass holder It should be a reasonably tight fit without needing a lot of pressure to fit through its bore.
You say the Grub screw's bottomed out... will it carry on threading into the bore of the brass part with the pin removed In theory, it should keep on screwing right the way through. If it doesn't then the tapped hole for the grub screw may be partly blocked or not threaded all the way through

Cerwyn wrote:

Hi Sam

Looking at your original photo of the Detonator Pin, could the pin be a Marushin MP40 part it looks very similar apart from the tapered "skirt" mid-way along.
Try measuring the the largest diameter end of the pin, how does it compare to this drg:-

https://mp40modelguns.forumotion.net/t1470-marushin-mp40-detonator-pin-dimensions-drawing

Hi Cerwyn, the diameter of the largest end of the pin is identical, however, the length is shorter.

Cerwyn wrote:

Next, how loose a fit is it in the brass holder It should be a reasonably tight fit without needing a lot of pressure to fit through its bore.
You say the Grub screw's bottomed out... will it carry on threading into the bore of the brass part with the pin removed In theory, it should keep on screwing right the way through. If it doesn't then the tapped hole for the grub screw may be partly blocked or not threaded all the way through

The pin requires no pressure to fit through the bore of the holder, it just falls in and out without any assistance until I tighten the grub screw.

After a bit of tweaking the grub screw passed all but about 1.5mm of the way through the holder but it doesn't seem to hold the pin, it still rocks even if the screw is fully tightened.

OK, going by your reply, it sounds as if the pin's widest diameter end is possibly too small to fit the brass holder. It could be too loose in there for the grub screw to get a good grip on it
I wouldn't expect a pin to simply fall in and out of a hole it's meant to fit, it should be a snug fit at least. The grub screw should lock it in place as soon as it makes contact with it, then tighten 1/2 to 1 turn or so.

I'm tempted to suggest you wrap some PTFE tape, or even PVC Insulating tape if there's enough clearance, around the pin and re-fit it. See if the grub screw nips it up tight then...

The pin needs to be dead centre of the brass holder ideally so it sits centrally in the Det.Chamber.

By the way, which cartridges are you using Sam

My own Sterling's Det.Pin (made to fire MGC p220 carts) is with a mate of mine at the moment but should be back early next week. Maybe looking at it might glean some answers

Tried the PTFE tape but it worked it's way loose again. Unfortunately there is insufficient clearance to put PVC tape on it.

I do, however, see what you mean by how snug it should be.

I haven't even thought about cartridges yet. It's been more a case of open box, remove model gun, try to fix model gun... I can't even get the screw out of the grip to fix the selector, it just turns a quarter turn each way then sits there.

Thanks for the help though, it really is appreciated, if it wasn't for you guys I'd have probably given up by now.

Not sure what the problem is with the pin but it was a replacement part (P220 pin with detonator chamber) purchased from Francky as a recommended upgrade on the original pin so it should be the correct size

Hi Paul, I don't get it either, everything I know about the real world tells me this should hold in and it just doesn't. I suppose it's the little bit of extra space causing the pin to wiggle it's way loose. Even with the tape it eventually just works it's way out.

It may be that the grub screw sits a bit loose in the thread and small movements of the det pin are making the grub unscrew.
I dont know what access to tools you have but you could
a)try drilling/tapping another one ( possibly two ) grub screw holes and fitting more screws.
b) get a new det pin that sits more tightly in the holder
c) add some thread lock to the existing grub screw.

These made entirely from steel would be better (less wear ) although the caps are less corrosive to brass

DOC

Conversion to fire MGC's P220 cartridge was the "standard" so it makes sense that a new pin bought from Francky would be intended for the P220s.

Both my Sterling and MGC68 MP40 have been converted to fire P220 cartridges and use this type of Detonator Pin. The drawings I posted up here are of the pins fitted to my own models so dimensions ought to be pretty much the same.

I'm going to stick my neck out and suggest that you try fixing the pin into the brass holder with Araldite or similar epoxy resin. This should harden enough to hold the pin in place.
Once assembled and fixed, there's no real need to remove the pin from the brass holder again. Cleaning it is dead easy with it still in one piece so you may as well permanently fix it together.
If Araldite does the trick, you could even solder it in place later

One thing to watch out for though is that P220 cartridges are nigh on impossible to find these days. KSC 9mm Luger c.p. cartridges are a good alternative and work in some Sterlings and '68 MP40s without any modification. I did have to open out the chamber in my MP40 a fraction though to stop them sticking but the Sterling fires both types without fuss.

Sam

I'll send you 5 new P220 cartridges FOC




Paul

Hi Sam
You seem to take a good picture:)
is it possible to insert the pin, screw up the grub screw and take a close photo of the "bottom" face to show just how much play there is please? this may shed light/allow for some more ideas to come forward:)

ATB

Hi,

Here are a couple of pics showing how much play there is. There's not a lot of play but it's enough.




Thanks for the suggestions so far. I was actually thinking of araldite or another semi-flexible glue to just stick this in place or perhaps give the pin the extra fraction of a millimetre it needs.

Thanks Sam
Seems a pity to glue it!
The best solution would be to file a tiny "flat" on to the pin where the grub screw tightens on to it, this would just be enough to stop the pin coming out, then as doc suggested add some thread lock to the gub screw hole before tightening (also a little in the pin/gap) then tighten good and hard (without stripping the thread of course!!) This WILL work. No reason on earth why not!
VERY rough diagram of what I mean

Now that is a brilliant idea. Fixed my selector too!

Thanks for everything, all of you.