[Bill_Rights]

I have a Mini-30 model 5854 GBCPC "Tactical" version of ~ 2011 vintage (ser. no. 581-94XXX), and I got complaints from fellow shooters and bystanders beside and slightly behind me on the firing line at a recent shooting outing in open air, in a farm field. They said "Dang, that rifle is LOUD!"

I also have an older model stainless woody Mini-30 with straight muzzle, and I never got such complaints. It's louder than a .22LR by far but a "tame" rifle, most people think. (Same ammo mix as for the GBCPC tactical shoot.)

The main difference I can identify between the two rifles is the flash hider on the GBCPC Tactical (well, the barrel is 4" shorter, too, but I can't see that making much difference).

Are we dreaming? Does the flash hider make the muzzle report louder to those to the side or behind the rifle? As the shooter, I did not notice excessive loudness (but, of course, I was wearing ear protection and focusing on shooting). What is your experience or knowledge?

I did do a little homework on this forum. This exchange was related:

If you shoot a lot, it helps to keep the muzzle rise down and target in site. It does make the shots louder, directs the muzzle blast up and back more.

no, that is what a muzzle brake does. and it does NOT make the shot louder, it simply redirects MORE of the shot signature back towards the shooter thus changing what the shooter hears. the raw noise Impulse is still the same, but with a muzzle brake you might (depending on design) hear more of it.

a flash hider is designed to allow the gasses of the shot to blend with ambient air, expand and cool a little.

That conversation was on this thread:
Flash hider/suppressor; yay or nay, in case you wanted to get the full context and "drift".

Theoretically, I agree with Mr. Snuffalupagus that the total acoustic energy liberated by the shot has to stay the same with or without the FH, but the sonic energy of the muzzle blast could be re-directed. However, with no flash hider, the acoustic energy of the muzzle over-pressure can go anywhere and everywhere, including side-ward and backward. Looking at the GBCPC's flash hider, I see no particular reason that the blast energy would be reduced to the front and increased to the side or rear. All that energy can go to the side or rear without the flash hider if it wants to - there's nothing stopping it. Please explain....

 

[Tommygunner]

Yes if you have a muzzle brake or flash supressor it will be louder behind and to the sides on the gun. I am not going to bother explaining acoustics hell i probabally cant even spell it right. That is just the way it is. One look at a muzzle brake or flash hider should tell the story. There are holes in it that point to the side! A muzzle brake has holes that point to the back.
Anyone around the fireing line should be wearing hearing and eye protection. If they arent they are just plain dumb and it is their problem.
I have a 7mm mag with a muzzle brake. Its not loud. Its painful without earmuffs.
I was sighting it in last fall for deer season. Some kids were at the range with their little pop gun ar10s plinking away. Some werent wearing protection. I told them to "put their fingers in their ears this thing is loud" They thought i was joking. LOL! when i shot they were in visible pain holding their ears. They left shortly after that. When I shoot my bad boy it makes the metal roof over the shooting benches ring like a bell.

 

[usmc0341]

4 inches of barrel will make quite a bit of perceptible difference in noise. Consider a full sized M16 vs an M4 if you will. The further the muzzle is away from the shooter the less muzzleblast will bother the shooter for obvious reasons. Also there will be considerably more unburned (or burning powder) exiting the muzzle and igniting causing an increased muzzle flash with the shorter barrels.

The flash hider/ compensator works by redirecting gasses exiting the muzzle into the path of recoil which pushes the muzzle in the opposite direction helping to mitigate muzzle rise and also dispelling and breaking up the flash. Usually when this happens the gasses are forced to the sides and/or straight up causing seemingly much louder report to bystanders who are near this path.

Gasses are like water and will follow the path of least resistance upon exiting the muzzle. If you have a flash hider/compensator it allows the gas to escape vertically/ horizontally (design dependant) before actually clearing the end of the weapon. A barrel that does not have this feature typically expells gasses (report) straight forward/downrange and away from the shooter and bystanders making the report seem less loud.

A muzzle brake has the end closed off with a hole large enough for the round to exit. This essentially creates a wall at the end of a vented chamber that the expanding gasses hit. The gasses are immediately redirected and following the path of least resistance will escape through the holes designed for this.
I said all of that to say this. A shorter barrel firing the same ammo as a longer barrel will typically be louder with or without a flash hider/brake/comp.