The actual M712:
The M712 is just one of many versions of the Mauser C96 pistol (one of the first and perhaps the most successful semi automatic pistol of the 1890's-1900's) it was copied by many nations, Spain, China, Pakistan and others especially the Chinese, who just couldn't get enough C96's so they ended up making their own versions in .30 "Mauser" and there where also variants made to fire .45 acp!. Some of these copies where hard to distinguish from the real Mauser made C96!
The Spanish firearms firm Astra, introduced the first C96 variant that featured a selector switch (semi/full) this feature sold very well to the Chinese who issued them to their special forces teams.
Mauser (at first) ignored this new development of the C96, until they realized that Astra was in fact selling more "Mausers" than Mauser!
So, in the interest of regaining lost sales, Mauser developed the M712 "Schnell feuer pistole" (fast firing pistol) introduced in 1932, which featured a selector for the mode of firing, also a detachable 10 or 20 round magazine feature was added. When the shoulder stock was utilized, the Schnell Feuer Pistole was a capable machine carbine.
The C96 Mauser remained in production until 1943 when more urgent weapons manufacture was required from Mauser-assault rifles!
The Marushin M712: (kit version)
Marushin makes (or has made) at least 5 different versions of the M712. The factory assembled (ABS) version , the kit (ABS) the all zinc version, the factory assembled (HW) and the kit (HW)
I have the abs (model kit) version, that was made in the early 80's it was imported by the collectors armory, who with Marushin's help, included the assembly instructions in English along with the packaging .
I found this model kit in a hobby shop in 1990, it cost $75.00 with tax.( I wish that I could buy these kits here in the USA today for that price!)
Sadly, "political correctness" has caused these modelguns to disappear in the hobby shops and toy shops here in the U.S.
Note that where trademark would normally be stamped (or other wise marked) "Mauser" all it has is a simply milled spot where the trade mark "Mauser" was supposed to be, this of course has to do with U.S. import regulations, as Mauser is a registered trade mark in the U.S.
This often makes finding modelguns in the U.S. with the original trade marks fairly hard, they can be found though, but usually, they are more expensive than the non trademarked examples.
In fact, the box the kit came in has the trademarks obscured on the other modelguns pictured on the front and sides!
The cartridges are machined brass (9.5x32mm) and are unique to the M712, they come 5 to a box.
They are of the typical Marushin Plug Fire Cartridge design, with the threads near the base of the cartridge, with a steel fixed pin in the removable cartridge base, a simple machined brass piston and a one piece body with threads at the bottom for the base.
Once again, the fact the threads are near the highest gas pressures and provide very little sealing properties, in fact allowing the gas pressure to drop faster, and provide less power for the "blowback" feature, often causing weak sluggish actions and jams.
Partially, this problem can be addressed, either by adding what is called a "intense-sheet" (a little rubber washer or O-ring in the base of the cartridge meant to seal the threads) to help control the gasses or to grease the inside of the case before the piston is inserted, this helps to control the friction and will help considerably.
Please note that even though two caps will fit and function, this is often very destructive to the cartridges, often causing cracks in the threads at the case bottom (often causing the base to break off!) and the cases sometimes "bulge" due to the excessive pressures which destroys the case.
Also, since the fact that the cartridges are expensive and are hard to find here in the U.S. should cause a little more care to be given to promote case life. But the single most important step, is to keep these cartridge cases clean This is important if you want to "shoot" these modelguns.
The assembly of this kit was facilitated by the fact that the instructions where printed in English and although this helped, the standard Japanese modelgun instructions feature excellent illustrations. And if you are an experienced modeler you don't need the instructions anyways!
Perhaps, The biggest challenge for me was removing the casting flash ! even with out the instructions, the kit builds fairly easily due to the fact that this is (or was) a well thought out model. Marushin apparently manufactures this kit from time to time, so they might be available at this time.
Although, it is not a simple kit by any means, as it has some tricky assembly steps, it still is one of my favorite model gun kits.
From start to finish, I probably had a little over 3 hours involved in assembly and, what is really cool, is that the Japanese include small tubes of ABS cement and grease to help in assembly.
Be sure to use light oil, grease or silicone (preferably the supplied grease at first) on the working parts and smooth any rough edges as friction is the 1# enemy of all modelguns.
Firing the Marushin M712:
When I first bought my M712, it came with a box of 100 MGC? brand caps in a Marushin? (This was my first modelgun that had the "blow-back" feature as all of the others where just for looks..
At first, I noticed that when I fired it in the semi-automatic mode, it functioned great! and it successfully fired off all 5! supplied cartridges.
However, when I selected full auto, it would fire 2 shots then it often would refuse to fire the 3rd cartridge.
I thought perhaps that it might be something I possibly missed during assembly, even though everything was correctly assembled according to the instructions, it still refused to fire full auto reliably.
Still, this modelgun simulated the firing cycle of a real M712! although, I was still disappointed that the full auto function was unreliable.
I knew that there had to be a fix for this "problem" but I was running low on caps at the time, so my experiments on this M712 stopped (12 years ago!) Soon, after discovering Shiraaya's modelgun website, he featured a Marushin M712 that originally, had the same problems as my example, but he had soon fixed his to fire full auto reliably!
Fixing the M712:
The problem was traced to the hammer timing, in the semi auto position the disconnector of course, stops the hammer from following the bolt down allowing the hammer to have enough energy to hit the firing pin thereby setting off the cap/s for the following shots.
What was happening in the full auto position, was the hammer was falling too soon in the firing cycle i.e.. the bolt has to be closed completely before the hammer falls, otherwise the hammers energy is wasted by hitting the lower part of the bolt just below the firing pin, before the cartridge is chambered fully therefore the hammers energy is wasted on the bolt instead of the firing pin.
Also, the problem seems to be in the cartridge, the fact that the piston seal is the cap, the inside of the cartridge case has to be clean and lubricated with grease, otherwise, the friction created by the cap/piston sliding back due to being pushed by the detonator will slow down the action enough that the momentum will be lost and miss-fires will occur.
The "auto sear" which controls the hammers fall needs to be adjusted by careful file work until the bolt (when the trigger is held down and actuating the bolt manually) causes the hammer to fall when it reaches the fully closed position. This is a very tricky adjustment and it is easy to over file the parts leading to more problems.
I still have a ways to go perfecting this modelgun, but I am still working on it!
The Marushin M712 and the 10 and optional 20 round magazines
Marushin makes two magazines for the M712 a 10 round (std) and an optional 20 round version. These magazines are constructed out of heavy sheet steel and are blued quite nicely although, they have some rough edges that need to be smoothed out in order to feed properly.
Also, they make the cartridge clips (also known as stripper clips) that hold 10 rounds.
You insert these cartridge clips into the guides in the upper receiver (when the bolt is in the full rearward position) and "strip" the rounds into the magazine with your thumb, and after the cartridge clip is removed by pulling up on it, the bolt will close chambering a round.
The video was "shot" using the Marushin "silver" caps. I fired more than 70 rounds to get the video.
Note that this M712, and other modelguns aren't very loud, even though the video was shot in a small room.
The fact that these modelguns aren't loud, is nice because you can shoot these just about any time (within reason!) I am still having some troubles with the M712,and although the "bugs" are slowly being worked out, it is still one of my favorites.
Click here: for the M712 video
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