Fallschirmjager.net - MP-40 Blank Firing SMG


As you have probably already heard SS Room and Military Precision have ceased operations. Fortunately it looks like two blank ammunition vendors will be producing blanks for us. Robb at Atlantic Wall Blanks and Joe Swanson at Motion Picture Blanks, Inc..

SS Room Blanks, BFONGs and magazines are available through NJ Sekela of Butler, NJ, USA. Here is a link to magazines, and a link to the BFNG MP-40 current price $2899.

Robb calls the blanks for the BFNG MP-40 a 5.56 Kurtz to avoid any confusion over the special 9mm size required by the BFNG. It is a short 5.56mm blank that works as a for backwards firing 9.3mm SMG's (Mp-40, PPSH, Sten, Thompson). The very early manufacture BFNGs would accept a regular 9mm blank, but most after the initial production run will not. Improved version of the original round with no powder leakage, and no jaming in the magazines.

I received the 5.56 blanks I ordered from Atlantic Wall today (04Oct10). Here's a test fire video, the MP-40 performs flawlessly with the 5.56 Kurz blank from Atlantic Wall! These rounds also stack and feed much better in the SS Room magazine, a major improvement! Click on the photo to see the video test…

Click on the photo to see the video test...

And a few words of advice from Chuck (the designer, creator of the MP-40 BFNG) "Some guys continue to use other blanks – they should understand that in using them not only do they risk damage, injury, etc, they also fall outside the ATF letter. The ATF letter is very specific in the system using the 9.3mm blank and was what every BFONG was manufactured for prior to being sent to customers. I have heard that some owners changed the chamber dimensions – again they fall outside the letter and own something that is actually against the law due to it not being evaluated.'

I'd echo Chuck's words - Do Not Alter the chamber! Very bad idea that.

The two primary weapons of the Fallschirmjager, Mauser Kar-98k and the Erma MP-40 submachinegun.
The blank firing MP-40 is available from Military Precision. The MP-40 is a major asset in tactical
reenactments, and a lot of fun! Since it isn't a firearm it is not subjet to restrictions on carry and is safe.

Fallschirmjager reenactor with blank firing MP-40.

Chuck Ducastel demonstrating his blank firing MP-40.

Modifying the SS Room BFNG

Start with a complete dissassembly of the BFNG. This is outlined in the manual, however
it is strongly recommended that you are skilled

mechanically or a gunsmith. The SS Room
manual is available as a PDF here the relevant portions begin on page 18 under complete breakdown.

You should also realize that this procedure is not recommended by the manufacturer of the
BFNG and will obviously void your warranty as well an any remedies against the manufacturer.
This information is presented as an example of my tinkering solely as entertainment and not
meant as a turorial nor a reccomendation that you undertake to perform this modification. One
trick that's not well outlined is that the cocking handle screws out, but only while the bolt is
aligned with the false safety slot.

While it is all apart you will want to take the opportunity to clean everything, since it is not
possible to really clean the BFNG without breaking it down.

The muzzle nut removed and a 3/8 x 3/8 16 hex plug needed to replace the old means of
capturing gas pressure. Drill a 1/8 hole through the hex plug.

Tap the barrel for 3/8 x 16 pitch, tapping requires patience, cutting oil and steady work,
stopping to clean the filings often as you go. You don't want to break a tap!

With the plug inserted now you can shorten the muzzle nut. I took about 1/8 off of each
end using a cut-off tool in the lathe. Then chamfered the edge and blued the newly exposed
ends. Final step is reassembly of the BFNG. I also took this opportunity to compress the
magazine well a bit since it's fit was a little sloppy originally.

Here's the finished job, it looks a little better than the original to me. I've opened up the gas plug diameter a bit through trial and error to obtain the right gas pressure for best operation. This is similar what's been done over the years to permanently blank adapt Garands, P-38s and other gas operated devices. Very important safety tip, loctite the screw and check that it is tightly seated prior to operation.

For a short time I was experiencing horrible malfunctions, I could only fire at most two rounds before the gun would jam, because of failing to extract the empty case. This was preplexing, but I ultimately found that the extractor claw retaining pin had sheared and the claw was no longer holding any tension on the cartridge rim. Fortunately this was totally unrelated to the modification. I originally solved the problem myself by turning a new pin on the lathe; which worked but eventually sheared again.

I've come up with a more permanent solution. The machined pin either has to be soft metal, which deforms or hardened, which causes it to be brittle and eventually shear under the hammering the bolt takes. So the better solution was to use a 3/32" roll pin (also called a spring pin). The roll pin has much better shear strength so it won't break. The roll pin needs to be long enough to support the extractor on both sides, but not too long to extend outside of the bolt - or it will hang up. You may have to shorten the pin to keep it from protruding, filing or grinding works best - don't grind it so hard that it heats up too much - you don't want to loose it's temper. You can find these pins in the specialty hardware section (bolts & nuts) at most home improvement or hardware stores. And the MP-40 functions flawlessly now.

A view of the MP-40 completed. All in all the Military Precision (formerly Schoessler's Supply
Room) blank firing MP-40 is one hell of a nice product and I'm totally pleased with it. This
is just my little finishing touch to a great toy.

BFNG Ammunition Sensitivity

The BFNG is sensitive to ammunition... (more to come) start here Historiker

Avoiding problems with SS Room blanks: The SS Room blanks do not have a sealed tip; i.e. the tiny opening where the nose of the casing is crimped being sealed with some paint or sealant, they will leak powder. After being handled a few times a significant part of the powder leading to a lot of squibs and stovepipe jams in the field.

At the Brownwood tactical I had a perfect ambush on six Amis laying in a ditch looking the other way. After crawling up I raised up and the BFNG fired one round and stovepiped. S**t! Six GI's with Garands turned with surprised looks. Needless to say their Garands didn't jam and I was toast. I now look for ones that are more 'open mouthed' and cull them. The others I seal with a dab of nail polish. You can see this clearly by example in the photo of the two rounds below, even just taking one out to place it for a photo some powder dropped out. You can see it just above the last "m" in the SS caption. Great recipe for lots of dud rounds.

Problems with different manufacturer's ammunition...

I let a friend of mine borrow the MP-40 for Waxahachie. He was looking forward to full auto fun as a change of pace from his Kar98K bolt action. He bought some 9mm blanks (Prvi Partizan) that were recommended by one supplier as ok for the BFNG. Turns out not to have been true. He rarely got more than one shot off before it jammed. The first sign of trouble was the he could not get the rounds to load well into the magazines. They didn't seem to hold more than 20.

Prvi Partizan 9mm blank on the left (PP); SS Room 9mm blank on the right (SS).

On first inspection I noticed that the PP rounds would only fit half way into the chamber without having to use pressure to seat them. Not good! The second problem was that the PP rounds were very hard to push out of the magazines, they seemed to be linking together at the top of the magazine.

Comparison drawing Prvi Partizan 9mm blank dimensions on the left (PP); SS Room 9mm blank dimensions on the right (SS).

The next step was to use a micrometer to measure the blanks. The PP blanks that he was using are different in size from the SS Room blanks. The key differences in the cartridge dimensions are that the PP have no taper to the shell casing portion; having a constant diameter of almost 10mm until the narrowed portion that simulated the bullet. The SS have a slight taper to the casing portion starting at 10mm narrowing to 9.5mm. The SS drop right into the BFNG chamber with no binding.

Both the PP and the SS 9mm blanks work flawlessly in my P-38. (Which is a real weapon, not a blank only non-gun.) The dimensions of the PP 9mm blank round directly correspond to the specifications of the real 9 x 19 Parabellum cartridge. The special chamber of the BFNG limits 'real' shaped 9mm cartridges from functionaing well. Hopefully you are not dumb enough to try a non-blank round. They do point back at you in the BFNG you know!

Drawing of Prvi Partizan 9mm blank rounds in the BFNG magasine.

The other difference is that the PP have a larger ejector portion with a steeper 45 degree angle at the base. It seems that this is what causes the 'linking' when the next round to feed is tipped up by the magazine lips. Thus it is much harder for the bolt to strip off a round into the chamber.

So Prvi Partizan 9mm blank rounds are perfectly fine, just not in the SS Room BFNG.

Important Disclaimer! - This is a non-political web page dealing with the history, equipment, life and campaigns of the World War II German airborne soldier (Fallschirmjäger) and World War II reenacting. This website is contains historical information as well as reenacting and living history information. This information includes reenactment photos, historical information covering operations, equipment and photos of World War II Fallschirmjäger in action. The information is catalogued and presented to preserve a clear eyed view of military history and present to the public an accurate representation of a World War II German airborne unit. We do not tolerate or condone any form of racism, radical or extremist activities, or persons with supremacist, fascist or racist political motives or beliefs and we do not support nor glorify the reprehensible policies of the Nazi Party. We do not tolerate, support, or condone any activities of any neo-nazi party organizations, any extremist, anti-immigrant or anti-semetic organizations.
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