I have read numerous post about the "do-hicky" on the end of the barrel of large caliber guns. Some refer to them as muzzle brakes, others refer to them as blast deflectors and some for whatever reason refer to them as flash suppressors. So who's right? Well actually everyone and some, except for the ones who refer to them as flash supressors.
Muzzle brakes are designed to reduce the recoil of large caliber weapons and in some cases to control the wobble of the barrel. This is accomplished by directing the escaping gases backwards through vents in the muzzle brake. This occurs when the projectile leaves the end of the barrel and momentarly pluges the hole in the muzzle brake forcing the gases through the vents. Notice on some artillery guns that there may be more than 1 set of vents each coming into play as the projectile procceds through the center hole of the muzzle brake and plugs them up. Artillery weapons are, for the most part, indirect fire weapons and the path and direction of the escaping gases have little or no effect on sighting the weapon. Not so with direct fire weapons.
Some of the late shermans and most all of the patton series of tanks except the 60 series, used a blast deflector. The design of the blast deflector works similar to the muzzle brake in that the projectile plugs the end of the blast deflector and causes the gases to be deflected. Same thing right? No its not. Where the gases deflected by the muzzle brake are directed backwards to retard the recoil, the gases escaping from the blast deflector are directed sideways and level with the vents. This allows the gases to escape without being directed into the direct fire sights and to help prevent kicking up a cloud of dust in front of the vehicle thus obscuring the gunners view of the target. Well then why isn't the blast deflector used on the 60 tank series? Well mainly because they're not that effective and the secondary expellation of gases from the bore evacuator will kick up a cloud of dust anyway. The bore evacuator? The long round can looking do-hickey surrounding the gun barrel. This "can" surrounds holes in the barrel that are aimed toward the muzzle. When the projectile passes these holes the gases are forced into this can at extremely high pressure. When the projectile exits the muzzle these gases are released and shoot foward toward the muzzle clearing the bore of remaining gases and spent propellant residue. The purpose is to clear the bore before the breech block opens on guns with recoil activated breech opening mechanisms. Some call this bore evacuator the fume extractor and if your compfortable with that so be it. The fume extractor IIRC is the big fan in the turret, used to clear fumes from the turret. Never worked though. One thought about the bore evacuator. The Sheridan has a bore evacuator but due to the nature of the propellant casing, requires a secondary system to clear the breech before opening. This is a Co2 system that directs a flood of Co2 into the breech cavity to extinguish burning embers. Before the invention of the automatic system we had to manually inject the Co2 and follow up with a swabbing with a wet rag.
I stated earlier that muzzle brakes are used on large caliber guns. This is true but they are also used on sporting rifles, shotguns, pistols and many military weapons. I believe that the 45 cal. Thompson had these and they are called cutts? Correct me if i'm wrong.
Flash suppressors. Designed to hide the flash of small caliber guns and machine guns when fired. Would be quite useless on tank guns.

I believe that clears the air of any remaining fumes and or gasses on the subject of the "do hickys". lol
Great explanation ARMDCAV!

Well tanks I mean thanks for clearing the air on that. Why does the M-110 have a muzzle brake on it?

The M110 dosen't have a muzzle brake. Few Howitzers do. The M110 a1 long barrel 203mm gun didn't have one but needed one, hence the M110A2 with muzzle brake. The M110 series are self propelled artillary, 203mm or 8".

I believe the bore evacuator is what causes the puff of smoke a second or so after the gun is fired. A bit of trivia. The bore evacuator on the 105 mm L7 is off centre so that when fitted to a Centurian, it could use the existing 20 pounder travel lock. It was never changed thus the L7A3 and m68's all have the same off centre bore evacuator.

Very interesting post ARMDCAV. Although I was familiar with each term, reading your post was very interesting and I learned a couple of new things. The other posts were very interesting as well. Keep up the great work guys.

Just to let you guys know I love posts like this. Most of you military guys have forgotten more than I ever knew. this will help a lot in the weathering process, now I will know which way the gas would be leaving and where it would leave more stains. If anyone is thinking of writing something like this and wonders if anyone will take the time to read it rest assured I will and I am grateful for each one.

The early Thompson had a Cutts compensator to reduce muzzle climb.

Great post, ARMDCAV. If I may clarify: the bore evacuator is intended to clear gasses and fumes from the breech area of the gun, reducing the noxious crap the crew is exposed to. Modern tank guns use propellants that produce quite a bit of ammonia and nitrous oxides. Inhaling this brew is irritating in the short term, and potentially hazardous over long exposures. So, the bore evacuator is intended to pull those gases from the breech by pushing a slug of gasses out behind the projectile. This pulls "fresh" air into the breech area, and clears the fumes (mostly...the cases/stubs tend to smoke a bit.).

BTW, modern 'combustible case' tank ammunition produces a short "stub" rather than the full length casing ejected from earlier guns. The "stub" is just the base and the first couple inches of the shell casing. This eliminates the frequent need to toss the empties out of the loaders hatch in heavy firing. Anyone else have burn scars or ruined boots from standing shin-deep in empties (M60-series and earlier)? Those steel cases were HOT!

Whether an artillery piece needs a muzzle brake is a function of the carriage. Lightweight carriages, or very powerful cannons, require the muzzle brake to reduce the recoil forces far enough not to damage the carriage or recoil mechanism. This is common in vehicle mounted cannons (M109, the-vehicle-formerly-known-as-Crusader), as weight is often an issue in designing such things and the carriage weight is an important factor of this. The M110 is seen both with and without the muzzle brake, because there were actually two different cannon barrels used (8" and 175mm). The recoil mechanism could handle one without help, but not the other. (I'm sorry to say I can't recall which required the brake. ) There is little visible difference between the two besides this, and both were known as the M110 when mounted on the vehicle.

Just as an aside, the original Leopard C2 upgrade called for the retention of the welded stel turret upgraded to include a thermal sight and a new Royal Ordnance hig pressure low recoil 105mm. this gun was to have been produced to the same standards as the 120mm CHARM gun so it packed a great recoil wallop. Apparently it had the same penetrating power in 105mm as the old 120mm on the cheiftain. To counteract the recoil it was to have had a large muzzle brake. It also had a concentric fume extractor. Would have been nice but there wasn't enough money in the budget and we went with the Leo 1A5 turrets for the retrograde upgrade C2. I guess the government of the time feels it is important to give any potential enemy a fighting chance. (I guess they're never gonna promote me now!)

Man!! As usual, great post ARMDCAV!................keep it up. I am on the same team as 'drewgimpy', when he states " rest assured I will, and will be grateful for each one ".

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