Does A Can or Suppresor Increase Back Pressure and Decrease Velocity??? Well????
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Very interesting insight. Is changing the RPM/Torque curve due to a muffler like changing the pressure and velocity profile in the barrel? I don't know, but the mufflers they made me put on my 1970 429 Cobra Jet Cyclone GT sure cut down on its velocity in the 1/4 mile!
Header cutouts at the track solved that problem.....no more silencer!
My experience is a slight increase in velocity but not worth the carbon build up on the muzzle face. If I was only shooting a few rounds then a CAN would be ok but I prefer the muzzle break and less cleaning along with less recoil. I have suppressors for everything but rarely use them do to increased recoil and carbon build up. If I am going hunting for coyotes then I will put one on.
I'm with you on the carbon build up at the muzzle. I've got to clean at about 50 rounds.
cohunt
Well-Known Member
As far as mufflers--- "made you put on" vs. "chosen by chassis dyno testing" makes a huge difference. Also, people sometimes will test only horsepower acceleration testing on engine or chassis dynos--- don't forget on a car/motor there are also "roll down" numbers to consider -- this number is basically how fast you loose horsepower on gas let off. In drag racing this wouldn't matter, but circle or road track racing it does.Very interesting insight. Is changing the RPM/Torque curve due to a muffler like changing the pressure and velocity profile in the barrel? I don't know, but the mufflers they made me put on my 1970 429 Cobra Jet Cyclone GT sure cut down on its velocity in the 1/4 mile!
Header cutouts at the track solved that problem.....no more silencer!
As far as carbon build up in a can goes-- it takes quite a while for that to happen--- I have a few thousand rounds through each of my cans and notice no buildup internally. ( unless it's my 22lr can, but I was under the assumption that is both carbon and lead buildup in a 22lr can) I do get a slight increase in muzzle carbon build up on the barrel though--- but I get more with a side port brake than with a can.
The biggest difference I see with my cans is poi change. Some people say that a can doesn't effect point of impact--- I have not seen this in my guns-- I definitely have a different point of impact with the can on vs off--- though it is extremely repeatable. But the same goes for a bare muzzle vs a braked muzzle-- I get different poi's I think this is more a function of barrel harmonics though.
As far as accuracy goes--- I get the same or better with a can on--- I have not seen any degradation of accuracy in my guns when a can is added.
I think that the barrel of a gun has far more "back pressure" possibilities than a can does-- the volume of the can is more than the barrel but both are still open to the 14.7 psi atmospheric pressure--- besides, a barrel opening is only caliber size, but the opening on the end of a can is larger than caliber (to avoid baffle or end cap strikes)
My real world experience with a SAKER 7.62
Gas guns (AR) with mid length gas system. Increases gas and changes the brass throw to almost forward vice 4:00 (over-gassed). This is why I use SLR adjustable gas blocks and know the "clik" settings just like you would know your rifle loads DOPE. Turn down the gas and you are back in business. I guess you could say this increases back pressure but also increased velocity slightly 10-15 FPS. I don't really consider that much of a big deal in a gas gun because it isn't running a maximum load and that FPS difference is within my margin of error on plinking rounds I made on the Dillon.
Bolt guns: Increase in velocity 10-25FPS depending on the load. I have never seen a decrease in velocity nor did I see any pressure signs on my warmer loads with can on vs can off. Always an increase.
Brakes? Never seen a decrease in velocity on an threaded brake my guess is its pass the actual barrel at that point and gas is venting already. Maybe on a brake system that has holes drilled or cut into the barrel could bleed some gas before the projectile leaves the rifling.
How about a rifle with a can that uses the brake as the mount? What I have seen on mine is velocity once again increases slightly.
Hope this helps.
Gas guns (AR) with mid length gas system. Increases gas and changes the brass throw to almost forward vice 4:00 (over-gassed). This is why I use SLR adjustable gas blocks and know the "clik" settings just like you would know your rifle loads DOPE. Turn down the gas and you are back in business. I guess you could say this increases back pressure but also increased velocity slightly 10-15 FPS. I don't really consider that much of a big deal in a gas gun because it isn't running a maximum load and that FPS difference is within my margin of error on plinking rounds I made on the Dillon.
Bolt guns: Increase in velocity 10-25FPS depending on the load. I have never seen a decrease in velocity nor did I see any pressure signs on my warmer loads with can on vs can off. Always an increase.
Brakes? Never seen a decrease in velocity on an threaded brake my guess is its pass the actual barrel at that point and gas is venting already. Maybe on a brake system that has holes drilled or cut into the barrel could bleed some gas before the projectile leaves the rifling.
How about a rifle with a can that uses the brake as the mount? What I have seen on mine is velocity once again increases slightly.
Hope this helps.
Last edited:
BrentM
Well-Known Member
Didn't read the threads and assume it was all covered but run a can on a AR and you generally have to change the gas block setting. In a bolt action I see the chamber and barrel get dirty much quicker and also notice more flow back when the case is extracted. From a redneck perspective I see the back pressure as being higher, the pulse wave changed, and the whole thing being dirtier. I love cans for the most part, hate them for this reason only. I clean my chamber with a chamber cleaning kit from Boretech and never had to do that before cans.
I searched LRH and found this thread which is very interesting and it has a lot of comments by folks who make and sell
muzzle brakes and understand fluid flow dynamics through both suppressors and muzzle brakes. Very interesting.
Especially comments by IdahoCTD and JE Custom in this thread.
www.longrangehunting.com
Looks to me like the conclusion is suppressors increase velocity very slightly in the range of 10-30 fps on most rifles and that
muzzle brakes have no statistical difference if they are designed correctly, though this thread details a member who lost
47 fps when he changed muzzle brakes......pretty unusual.
muzzle brakes and understand fluid flow dynamics through both suppressors and muzzle brakes. Very interesting.
Especially comments by IdahoCTD and JE Custom in this thread.
Can switching muzzle brakes change muzzle velocity??
So I recently had a new muzzle brake installed on my 338 RUM, and my muzzle velocity dropped about 47 FPS. With the last brake I had this rifle/load dialed in. I'm using a Magnetospeed and have fully characterized this load several times across temperatures and it has always been very...
Looks to me like the conclusion is suppressors increase velocity very slightly in the range of 10-30 fps on most rifles and that
muzzle brakes have no statistical difference if they are designed correctly, though this thread details a member who lost
47 fps when he changed muzzle brakes......pretty unusual.
Agree here completely and also I may add that the Brass is dirtier and has a completely different appearance. Brass appears to have some discoloration around it from flowback in my bolt guns.
Maybe not exactly what you're looking for BUT.
I have a few AR's and this is really the only place I've noticed it. I have some light 40 gr loads for my .223, They will not cycle withOUT the suppressor attached, but they do cycle perfectly with it attached.
Also, before I got my suppressor I had a load set up in either my 6 predator or 6.5grendel, can't remember now. But it shot great and brass looked perfect. After I got the suppressor, I immediately got some shiners on the brass. In every rifle I've had to turn down the gas port which suppressor attached.
