Loading Mulberry Field .357 Double Capped Cartridges

Last edited by Cerwyn on Sun Oct 28, 2012 10:20 am; edited 2 times in total

Loading Mulberry Field .357 Double Capped Cartridges

Double Capping cartridges is something not normally recommended for PFC modelguns. The usual PFC, C.P. type cartridges are designed to use a single cap. Modelguns, especially Semi Automatic and Automatic models requiring blowback to cycle slides or bolts work well using the power generated by a single cap. Two caps often result in damaged cartridges and also damaged Modelguns.

Mulberry Field's Double Cap .357 Magnum cartridges are designed to use two caps safely. These cartridges fit Models of S&W .357 Magnum revolvers. My own Model is a HWABS Kokusai M19. Being of HWABS construction, the barrel is open apart from a metal plate fitted along the barrel's length. This plate ensures that projectiles of any description can pass through the barrel but it will allow smoke, sparks and muzzle flash to pass through.
Blowback is not required and all the energy generated by two ignited caps passes through the cartridge's nose and out through the barrel.

Component Parts :

Left to Right: 1. Copper Top 2. Sleeve 3. Firing Pin 4. "Primer" 5. Case
***NB These cartridges, as do all cap firing cartridges, use an imitation "Primer". It is a solid metal part used to imitate the appearance of a real Primer. In Modelgun cartridges, its function is to form a solid flat base for the cap to seat onto. Centre Fire type pistols or rifles will also use the imitation Primer to push the cap against the cartridge's internal firing pin when struck by the Modelgun's firing pin. Although described as a "Primer" in this and other articles here, Modelgun cartridge "Primers" contain no explosive compounds whatsoever.

Step 1. Insert Firing Pin into Sleeve.

Notice the Firing Pin has different diameter pins at each end.
Notice also the Sleeve is wider at one end.

Ensure the Firing Pin's larger diameter pin is inserted into the Sleeve's widest end as shown

The larger Pin is a slide fit through the hole in the Sleeve's opposite end and should look like this when you push it into place

Step 2. Load First Cap

7mm caps are used in these cartridges. Choice of cap is yours, Marushin caps produce more sparks which pass through the open barrel or MG caps which do give a decent muzzle flash in short barrelled revolvers.

The first cap needs to be pushed into the Sleeve's widest end. This can be awkward as the cap is positioned with the powder charge facing into the Sleeve. To make this job much easier, use Nail Clippers or similar to cut away the moulding flash or sprue left on the cap's edges when it's pulled from the frame

Push the cap until it sits flush with the Sleeve's base. Note that pushing the cap into the sleeve will push against the Firing Pin until it's passed through the opposite end.
***Take care at this stage not to force or tap the cap into the Sleeve. Excessive force could ignite the cap resulting in possible injury***
Once the cap is seated correctly it should look like this

and the opposite end...

The wider Firing Pin protruding from the Sleeve will strike the second cap once it's been fully assembled. You may just see in the photo above that the Firing Pin has a bevelled and sharp edge. This is intended to both ignite the charge and also cut through the cap's plastic base to allow smoke, flash and sparks and more sound to exit the cartridge and pass through the barrel

Step 3. Insert "Primer"

Fit the "Primer" into the Case ensuring it sits flush with the base of the rim as shown

Step 3. Insert Sleeve assembly

Fit the Sleeve complete with Firing Pin and cap into the Case, cap end to be facing the "Primer"

Step 4. Load Second Cap into Copper Top

Push the cap into the Copper Top and seat it home using the wider end of a Loading Stick. The one shown in the photo is a metal Kokusai tool supplied with the Modelgun. Plastic Marushin and MGC loading sticks also work perfectly well

Step 5. Assemble Cartridge

Screw the Copper Top and cap assembly into the Case

Check the "Primer" is still flush with the base...

Your cartridge is now ready to fire.

_________________
Cerwyn

Hobby collector of Replica model guns and Militaria.
also member of Living History Reenactment Groups.

Interested in loading 2 different types of caps in one round to see what you can get out if it Very Happy

? Reckon having the Marushin facing the front will get better effects (get both adequate spark & smoke Question

)...

Also remembering the times when the Japanese Customs lady stubbornly reckoned these imitation primers contained gunpowder and took it all off from me Sad

...

Interesting cartridge! I didn't know there were double-cap ones for revolvers. Cerwyn is right that without blowback it is less stressfull for a modelgun. I find a single-cap Kokusai revolver to be quite loud, must be even louder with two of these :-D

Hi jim,

As far as the Kokusai HWABS M19 is concerned, the standard single cap cartridge produces a good loud sound as it fires with the added bonus of muzzle flash thanks to the short 2.5" barrel.
Marushin's 7mm cap throws sparks out of the barrel which are effective, but probably not particularly realistic
MG caps on the other hand produce a defined yellowish coloured shaped flame which looks rather more like a real one.
I haven't tried this with the double cap cartridge yet, but adding a very small amount of Mg powder on top of Marushin caps makes really good looking red to orange flash at the muzzle extending out about 3" or so. This is the best effect I've had yet from using Mg powder
It will be interesting to try a mix of Marushin and MG caps with Mg powder in these Double Capped cartridges. I'll let you know how it goes

Hi smootik,
Kickback suggested trying these and I'm glad he did Although rather fiddly to load, the noise made by two caps igniting at once is noticeably louder than single capped cartridges. My ears were ringing after a couple of shots

_________________
Cerwyn

Hobby collector of Replica model guns and Militaria.
also member of Living History Reenactment Groups.

Hi
I use CAW Triple cap carts in the CAW SAA Smile

really good fun!!! Twisted Evil

JohnnyV wrote:: Hi
I use CAW Triple cap carts in the CAW SAA really good fun!!!

The difference in volume between 1 and 2 caps is immediately obvious, 3 caps should make one almighty bang
Are the CAW Triple Cap carts similar to the MF Doubles above i.e. will they work only with a model that doesn't have the modelgun's Detonator Pin in the barrel pointing backwards towards the cartridge nose
I've a metal Kokusai Colt SAA Peacemaker that uses cartridges similar to these

Loading Mulberry Field .357 Double Capped Cartridges Kok35712

I know my MF Double Cap carts will not work in the metal S&W M36 I've got as that uses the above type of cartridge design.

_________________
Cerwyn

Hobby collector of Replica model guns and Militaria.
also member of Living History Reenactment Groups.

Hi Cerwyn
Yes they will ony work with rear firing pin arrangement
They are true .45 cal very nice! all 3 caps seat in the normal way (none in reverse as it were as with above when you used nail clippers) 2 face forwards, one backwards, front 2 get lovely hole blown in them (great for then using in carts that need hole made (ie marushin .223 in some guns)
PICS:

Loading Mulberry Field .357 Double Capped Cartridges Img_0211

Loading Mulberry Field .357 Double Capped Cartridges Img_0212

Thanks John

As you've kindly posted clear photos of the CAW .45 Triple Cap cartridge I'd like to copy them and post them up as a "How To Load ... " topic if I may please

I also found the MF .357 cartridge cuts a neat hole in the cap sitting in the copper top. They are perfect as you say for later use as seals in Marushin .223 carts and also the old type c.p. MGC cartridges that were used before the introduction of rubber O-rings

_________________
Cerwyn

Hobby collector of Replica model guns and Militaria.
also member of Living History Reenactment Groups.

Of course:) no worries.
And yes a great bang Laughing

Guys, could you please measure these cartridges and provide new data for Cartridge Library? :-)
https://mp40modelguns.forumotion.net/cartridge-library-new-f52/sample-entry-template-for-submissions-t2460.htm

smootik wrote:: Guys, could you please measure these cartridges and provide new data for Cartridge Library? :-)
https://mp40modelguns.forumotion.net/cartridge-library-new-f52/sample-entry-template-for-submissions-t2460.htm

Certainly will smootik It's on my "To-Do" list this week.

_________________
Cerwyn

Hobby collector of Replica model guns and Militaria.
also member of Living History Reenactment Groups.

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