When Springfield Armory unveiled their new 18″ and 20″ Hellions, many of us noticed the 20″ version has a similar-looking barrel as the Croatian military-issued VHS-D2. It looks like it has a gas ring to launch a rifle grenade. So I took my review sample 20″ Hellion and tested it to launch practice rifle grenades. Here is that story.

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Put A Ring On It, To Launch A Rifle Grenade

Above is the marketing photo by Springfield Armory when they unveiled the longer-barreled Hellion. This is the 20″ Hellion. If you look closely, it has a bayonet mount. What was interesting was the ring and circular mount in front of the bayonet mount.

I took a digital caliber and measured the outer diameter of this section on the barrel. According to an online source (Ian McCollum), military rifle grenades should have a tube that is 22mm in diameter. This section of the barrel is just under 22mm and the split gas ring is just over 22mm. This should work.

I googled for an inert rifle grenade and found this company called Inert Products.

$143.80 for an inert rifle grenade? That seems rather expensive. I reached out to them to find out if their inert rifle grenade could be launched off a rifle using a blank. They said it could not. So I kept searching and found an online surplus shop that had an M31 practice rifle grenade for only $30! Now we are talking!

Here is a Photoshop render I made to see how the M31 practice rifle grenade would look on the 20″ Hellion.

The rifle grenade arrived and it was clearly used. But for the price, I did not mind.

The stabilizing fins have definitely seen better days. It is a strip of aluminum sheet folded into a cross and riveted to the tube body. More than half the rivets were broken off. I was more interested in the barrel fit than the fins.

Once seated against the bayonet mount, I can feel the gas ring providing pressure on the tube.

Researching Rifle Grenades

In my research for more information about rifle grenades, I came across these pictures of hand grenades adapted for rifle use.

I came across a manual that talked about how to use the M31 rifle grenade. The following excerpts are from BulletPicker’s online copy of the FM 23-30 Army Field Manual on Grenades and Pyrotechnic Signals.

The M31 practice rifle grenade is used to simulate the ballistic characteristics of the M31 HEAT rifle grenade. The M31 grenade is made of sheet steel and aluminum and contains no filler and no fuze. The M31 practice rifle grenade weighs 25 ounces and has a maximum range of 150 meters. There are no replacement parts for the grenade.

Interestingly, the image above and the manual do not recommend shouldering the rifle buttstock when shooting a rifle grenade while you are in the prone position. This tells me the recoil from the rifle blank will be substantial.

Here is a field expedient method for getting certain angles to shoot the rifle grenade at a given distance.

Apparently you could launch a rifle grenade off an M16.

If you want to read this manual it is hosted online. Click here to read it.

Shooting The Rifle Grenade

Most people are familiar with the rifle grenade sight on the SKS. Lift it up and it shuts the gas to the piston. Well, the 20″ Hellion only has a two-position gas block. “N” for normal and “S” for suppressed. Add to the fact that there is a 20″ barrel eating up some of the pressure of the rifle blank used to launch a rifle grenade. I decided to take it slow and test the function of the rifle grenade on the 20″ Hellion by using the same 5.56 blanks I use for my can cannon.

Take into consideration that the M31 practice rifle grenade weighs twice as much as a 12oz soda can. Can launchers have at most a 2-inch barrel and then an expansion chamber before the soda can but I am not sure if that is the same volume as a 20″ Hellion barrel. Can Cannons shoot a 12oz soda can about 100 yards. So maybe I will get 50 yards or less with the Hellion and M31 rifle grenade?

Nope. It went all of about 10 yards. LOL.

Look at the small pistol target in the middle. You can see the rifle grenade pointing to the ground about to hit it.

Well, that was severely underwhelming. LOL. But I knew that the rifle grenade would not go far, I just did not expect it to be that short. Normally the Army uses an M195 rifle blank. So I ordered some from Atlantic Wall Blanks. However, as I am typing this article, Atlantic Wall Blanks no longer lists them on their website.

Rifle Grenade Re-Launched

The rifle grenade fins broke after the first flight. But the actual dummy grenade was still solid so I kept launching it 10 yards down range. Due to the lack of fins, it just tumbles. So my friend John Wild offered to design a 3D printable set of stabilizing fins for the M31 practice grenade. My friend Thomas was kind enough to help me print them out. I had to grind the remnants of rivets off the tube and then I could slide the stabilizing fin back on. I used super glue to make sure it stayed on. It was a decent friction fit but I figured super glue would be better.

So we retested and relaunched the M31 practice rifle grenade. As expected, the recoil was very stout. The recoil felt greater than a 12 gauge shooting slugs. The 3D-printed fin did not survive the first flight. But there was enough left that we launched it a second time. I have a spare fin that Thomas printed but I would have to remove this superglued one first.

Here is a video of both tests. The first few video clips are with the normal rifle blank and then the more powerful M195 blank and 3D-printed fins.

Final Thoughts On Launching Rifle Grenades

The U.S. Military no longer uses rifle grenades. We have M203, M320 and MK19 to launch grenades further than we can throw them. But some countries still have them in their arsenal. I suspect that is why HS Produkt still keeps this obsolete feature on their barrels and that is why it is on the 20″ Hellion.

It is fun to lob a juggling club down range about 100 yards but it isn’t really practical. This was just a test of the function that was designed into the 20″ Hellion. To my surprise, even though I set the Hellion gas block to the “S” suppressed setting, there was enough back pressure from the M195 blank to cycle the bolt, extract, eject and load the next blank from the magazine. So if you had a box full of these, you could keep shooting them until you run out of rifle grenades or blanks.