Thoughts on K-Baffle Mouse Hole

[mcrump]

What's the conventional wisdom on .22 k-baffle mouse holes. Should they be large or small?

[quietoldfart]

You'll see arguments made for various sizes. One of the most frequent I've encountered in this forum has been that the waist vent (this is the hole to which you're referring as a 'mouse hole' yes?) in the K baffle ought to be kept quite small, as the higher pressure gas will be able to push through easily but once the pressure drops in the coaxial volume it will have a harder time coming back into the bore. My own testing has shown that keeping it on the small side results in slightly worse than average suppression, and little to no detritus escaping the bore into that outer part of the baffles. Opening it up a little gets the outer area more dirty and assists in better suppression. Opening it still further worsens suppression. So 'medium' would get my vote, for what it's worth.

[mcrump]

Thanks for the reply. Would you consider the waste vent size that I am showing on the drawing to be small, medium or large.

[propeine]

Thanks for the reply. Would you consider the waste vent size that I am showing on the drawing to be small, medium or large.

At the moment, I would consider it small/medium but consider that those sharp edges left behind will erode somewhat quickly leavin you at a perfect IMO medium.

50% of the bore off axis and at bore diameter seems to be the general rule of thumb among most K-baffles I have seen.

[mcrump]

Do you have an opinion as to whether to use a blast baffle to eliminate FRP?

[propeine]

Do you have an opinion as to whether to use a blast baffle to eliminate FRP?

I did not. Given the chance to do it over again I wouldn't have ported my first baffle the same as the rest of them but I wouldn't use a blast baffle either. I just spaced it .275 off the end of the barrel. That said, your barrel threads are too short at .375 with your blast baffle the way it is unless you plan on shouldering on the muzzle of the barrel for everything.

FRP is negligible on a rifle and minimal on a pistol IMO but I also have nothing to compare it to nor has it been metered.
Videos in my build thread of both pistol and rifle.

[fishman]

the thickness of your caps at the thread reliefs is very thin, i would make that much thicker.

also, how do you plan to machine the round grooves in the endcaps and in the front faces of the baffles? a rotary mill table, CNC, or a face grooving lathe tool?

[mcrump]

Good advice. I was trying to get rid of as much weight as possible. I plan on grooving the caps on the lathe. I am also considering tapering the grooves and radiusing the bottom corners thinking that it would provide a bit more turbulence of the gasses. My existing caps do not have any grooves.

[Capt. Link.]

The coaxial port is not a mouse hole. The Mouse hole disappeared from K baffles a number of years ago.It was located opposite the coaxial port at the base of the conical skirt.

[fishman]

My existing caps do not have any grooves.

i was referring to this area

[mcrump]

Correct. This is a new set of caps that I was going to machine these just to see if there was any decibel difference.

[mcrump]

The coaxial port is not a mouse hole. The Mouse hole disappeared from K baffles a number of years ago.It was located opposite the coaxial port at the base of the conical skirt.

Link,

Are you referring to the slot in the large portion of the skirt or the hole at the waste? I guess I'm confused by the correct terminology.

[Capt. Link.]

The coaxial port is not a mouse hole. The Mouse hole disappeared from K baffles a number of years ago.It was located opposite the coaxial port at the base of the conical skirt.

Link,

Are you referring to the slot in the large portion of the skirt or the hole at the waste? I guess I'm confused by the correct terminology.

The hole in the large portion of the skirt is what was called a "mouse hole" do to the resemblance.The port in the waist is a coaxial port.
We had a post a while back that used a K diagram with all parts named.

[a_canadian]

There have been a few terminology discussions. This one may help:

viewtopic.php?t=92684

The term 'mouse hole" is applied to various holes. Usually incorrectly. The slots cut into the large ends of the skirts (cones) are indeed noise holes. Note the resemblance to a classic cartoon baseboard mousehole, as seen in Tom & Jerry.