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 Double capping..Why have we not thought of this before!!

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JohnnyV
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PostSubject: Double capping..Why have we not thought of this before!!   Sun Apr 01, 2012 1:42 pm

On the subject of the new Tanio Koba cartridges discussed here:
http://mp40modelguns.forumotion.net/t3349-tanio-koba-9mm-light-alloy-cartridge-first-impressions#20751

It struck me that why oh why have we not thought of this before??
The principle of an extra cap between the nose cone and piston will work with ANY CART in an open bolt design modelgun cheers

I tried this week with many guns and ALL worked fine!!!
The best results were with a Hudson Sten using standard Hudson sten carts!!
One cap loaded as normal and anothe facing forwards after the piston, in the sten it really pumped smoke out of the barrel with a much better bang!!!SmileSmileSmile

Also tried an MGC Thompson with standard carts = Worked great!!!!
Even thought what the hell and tried it (though loading caps a little tricky) in marushin MP40 = Worked great!!!
Works with P220s, KSC 9mm, Hudson 9mm, MGC .45acp !!

So conclusion = ANY open bolt SMG will work this way cheers cheers

Also tried double cap method with new Tanio Koba .45acp carts in MGC MEU and MGC V10
Result = no uncontrolled firing and great better bang, better sparks, more barrel effect all round!!!

This will lead to much more fun me thinks Twisted Evil
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ljerr2
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PostSubject: Re: Double capping..Why have we not thought of this before!!   Sun Apr 01, 2012 2:51 pm

You guys have got my curiosity up. Johnny - were you using the double caps in an open barrel tommy? I may have to try this next weekend! I'd love to see the effect of more foreceful and abundant smoke ejection!
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JohnnyV
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PostSubject: Re: Double capping..Why have we not thought of this before!!   Sun Apr 01, 2012 2:58 pm

Hi Jerrod !
Yep open barrelled MGC Tommy Smile great fun!!
If you can use Hudson inners as the hole in the piston center really comes into its own with this set up:)Smile but good with MGC inners as well!
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Cerwyn
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PostSubject: Re: Double capping..Why have we not thought of this before!!   Sun Apr 01, 2012 3:32 pm

Very Happy If only this notion had come along when caps were a lot cheaper to buy Rolling Eyes

Open barrels are what this method is intended for. The second cap plays no part in producing blowback as the ignited cap vents forwards out through the cartridges' nose and down the barrel.

Problems occur (pretty much always) when 2 caps are used to generate Blowback. Only Marushin recommended using 1 x 7mm & 1 x 5mm cap in their M16A1 and XM177E2. This was intended as a cure for the models' rather poor firing performance. Although the method helped a little, it wasn't the "Total Cure" hoped for and in fact led to early failure of cartridges as the extra pressure inside the cartridge tended to blow the cartridges' screw on base off. I've tried the 1 x 7mm + 1 x 5mm in MGC Thompsons, Marushin MP40 for example, but found the extra blowback sends the bolt back to fast it overpowers the recoil spring and the gun starts missbehaving as the bolt "runs away with itself". Models like Marushin's MP40 using ABS bolts soon break the bolt too.

BUT, as long as the second cap sits facing the open barrel it shouldn't cause damage. John's experimenting with various models and cartridges seems to be the way forward. Just keep an eye on cartridges for signs of damage, also Bolts, Detonator Pins & Chambers.

John, How did you load the second cap in Marushin's MP40 cartridge please Question i.e. which side of the brass dished washer Question

One thing I am keen to try is using the Hexagon Cut piston in otherwise standard MGC c.p. cartridges. The piston does seem to allow more smoke to vent than convential ones, just as claimed by T. Koba

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JohnnyV
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PostSubject: Re: Double capping..Why have we not thought of this before!!   Sun Apr 01, 2012 3:56 pm

Hi Cerwyn
"John, How did you load the second cap in Marushin's MP40 cartridge please i.e. which side of the brass dished washer "

I put the cap in first then the dished washer then then as normal,
Please note this was in a full metal marushin MP40 with a custom det pin, just tried it in a plastic marushin and it DID NOT work, cap wrapped around det pin:( I think that with the marushin carts it only worked in the metal model due to wider det pin end, the pointy det pin end in the plastic Mp40 seems to go through the cap and cause problems....

Also tried the metal marushin just now reset for P220s (different det pin) and It worked great with those....
Makes me want to set up the plastic MP40 for P220's Twisted Evil next on the list:)Smile
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PostSubject: Re: Double capping..Why have we not thought of this before!!   Sun Apr 01, 2012 4:35 pm

Thanks John, I had a nagging feeling that I'd tried this years ago with my ABS Marushin MP40 and hit the same problems you did, the caps started gumming up the Det.Pin. I couldn't remember for sure but you've confirmed it for me now.

I do remember, only too well, firing MGC P220 cartridges (single cap as intended) in the same ABS Marushin MP40. It made a lot more noise for certain, cartridges ejected harder too BUT the Bolt broke Crying or Very sad

The bolt assembly is essentially 2 parts, the Front plastic part is only held onto the charging handle assy by two spring loaded pins. Cracks appeared from each of the 2 holes in the plastic Front part that very quickly split the bolt. C.P. carts are far too powerful for the ABS to handle. Find a sollution to strengthen the bolt first and then give it a go Very Happy

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claymore
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PostSubject: Re: Double capping..Why have we not thought of this before!!   Sun Apr 01, 2012 8:36 pm

seems pretty obvious now you have said it so wht hell hell did we not think of this before, over easter going to have to try this out Twisted Evil
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PostSubject: Re: Double capping..Why have we not thought of this before!!   Sun Apr 01, 2012 8:43 pm

Hi Claymore

I Know what you mean! but its often the obvious that gets overlooked Embarassed

best result so far, by far, is using the now imposible to find Hudson inners.... gggrrrrr
In the sten even 2 shots has the smoke pumping out of the barrel!

SO..... Smile anyone want to sell me some hudson inners ????
I ASKED FIRST !!! lol! Cool
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PostSubject: Re: Double capping..Why have we not thought of this before!!   Sun Apr 01, 2012 9:56 pm

It was too obvious to notice ;-D

Hudson inners?
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PostSubject: Re: Double capping..Why have we not thought of this before!!   Sun Apr 01, 2012 10:01 pm

Hudson inners its the piston in hudson rounds they have a hole through the middle of the piston to let more smoke through trouble was in most guns it let to much pressure out so blowback was crap and we all replaced the piston with MGC ones.
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PostSubject: Re: Double capping..Why have we not thought of this before!!   Mon Apr 02, 2012 10:37 am

Here's a couple of photos of Hudson and MGC cartridge pistons:


Hudson on the Left, MGC on the Right
Claymore's spot on, Hudson's vented piston DID reduce blowback pressure enough to affect performance in some guns but it's possible that placing a second cap on top of it might seal in some pressure. Well worth a try ...

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PostSubject: Re: Double capping..Why have we not thought of this before!!   Mon Apr 02, 2012 12:14 pm

Ah, those pistons! Thanks for detailed explanations and pics guys, now I got it :-)
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