How do blanks work?

[chris in va]

Just something kicking around in my head.

To fire blanks in your normal semiauto handgun or rifle, does the recoil spring have to be changed out? If not, how does it cycle the action if the mass of a bullet isn't present?

Does it have the same powder charge as a normal round?

 

[SIGSHR]

I was told-over 40 years ago, when I was in the Army-that Hollywood propmen and armorers had various tricks to make semiautomatic firearms work without using blank adaptors. One version was they used sleeved barrels
that allowed the blank to generate enough pressure to operate the action. Which also made use of ball ammunition in such modified firearms impossible.Just reporting, I have never actually seen one. Merely changing a spring will do nothing.

 

[jimbob86]

I know that the gas operated M-16 needs a blank adapter present to reliable cycle the action .....

the m-14 as well ..... for funeral detail, we had to hit the charging handles ....

 

[Falcon5NZ]

In the RNZAF we used BFA's on the IW Steyr (Aussie made variant of the Steyr AUG), allowed a small amount of gas through so you still got a muzzle flash (although not as pronounced as without one, so it was fairly obvious if you fired w/o one. And they don't cycle either-ask me how I know )
It also had a tube that went into the barrel and I THINK that had the secondary function of stopping a projo going out the barrel full noise. We used blanks manufactured by Ordnance Developments Limited which are the same pattern as the US Brass ones but are green lacquered steel. In the transparent IW Steyr mags or a belt of 5.56 link a brass live round stuck out like a sore thumb

I do recall a trick with a turned down 5.56mm round in the muzzle of an M-16 to act as a BFA without being obvious and ruining the look e.g Memorials, Funerals but I don't remember exact details so I won't pretend to be an expert.

Now that's for gas operated weapons, which require gas "back pressure" to function. Recoil and Inertia operated may be different. I suspect you would have fun getting a Browning Auto-5 or Benelli M-2 to function correctly with blanks.

And some blanks do have a bullet, albeit a wooden one. Like the Smurf Killer

The BFA causes the projo to disintegrate as it leaves the muzzle.

You also have to realise that there are different types of blanks which can basically be classed as noise and launching. Noise blanks are for battle simulations while launching is for well, launching something (rifle grenades, lines etc). I've even heard that using a noise blank (accidently) to launch could result in a catastrophic failure due to the pressure buildup of a completely obstructed barrel.

They have different powders for the different rounds
The CARTRIDGE, 5.56MM, BALL, M855 has 26.1 grains of WC 844
The CARTRIDGE, 5.56MM, BLANK, M200 (noise) has 7 grains of HPC 13
The CARTRIDGE, 5.56MM, BLANK, M755 (launching cartridge specially designed for the M234 Riot Control Launcher) has 12 grains of Hi Skor 700-X (which if I recall correctly is a shotgun/pistol powder)

I may have veered off topic a bit but hope you can understand what I mean and you learnt something.

 

[2damnold4this]

We used blank adapters on M16s and m60s during during the 1980s. In my experience, the m16s ran ok while the m60s could be finicky with the adapters.

 

[jimbob86]

We used blank adapters on M16s and m60s during during the 1980s. In my experience, the m16s ran ok while the m60s could be finicky with the adapters.

IME, our M60's were "finicky" on a good day with live ammo, and downright unreliable on most days.

 

[dajowi]

We used to make our own blanks by pulling the bullets out of .22 cases and sometimes packing them with soap or wax. Worked well with revolvers but semi-autos not so well.

 

[DPris]

There are a number of ways used to make guns function with blanks, including screw-on & bolt-on muzzle devices, lightening recoil springs, partially plugging barrels to create sufficient back pressure to cycle, and so on.
For other guns that don't cycle themselves, there are also varying degrees of loudness in blanks, such as 1/4, 3/4, and full "sound" levels.
Denis