300 blackout build complete

[fishman]

There was definitely a ton of flow into the outer skirt area. The tube was very dirty, it was difficult to slide the baffles out. The majority of loose carbon buildup was in this area. All the buildup inside the baffles was hard and stuck on.

[a_canadian]

Well there you go. It's working. Interesting. I'll have to consider the specific geometry of your waist porting for a while.

[GTS01]

Very nice looking. I've just started looking into suppressors. As in a couple days ago. I started off just looking at factory builds then thought, well how hard is it to build one?! I'm finding it's not hard at all. Though there is a lot of science to it to be effective.

In the designs I've seen using freeze plugs and Maglite tubes I thought the sound was supposed to bounce off the back side of the baffles reflecting it toward the outer housing and back. I was thinking it might be beneficial to have another reversed cone that would then reflect it back toward the outer housing and the first cone to kind of keep the sound bouncing back and forth in the can rather than traveling out.

When I first looked at your baffles I thought that's exactly what you were doing. However after seeing the assembled picture I see it's not doing this at all. But it rather appears to allow the gasses to expand on the front side of the cone as the cone increases in diameter as the back side of the cone isn't accessible to the gasses/sound because the baffles are next to each other creating more of a void in that area.

So is the point to reflect the sound or expand the gasses? Or both?

From what I'm reading the "K" baffles are the ones with the 45° drill in it. Though I've not quite seen what the purpose is for this. Is it just to allow a path for gasses between the baffles? Or something else? What do K baffles do for the performance of the suppressor? Is it more to maintain accuracy and reduce POI shifts, or for more effective noise reduction?

Sorry for newbie questions. Like I said I just started researching this 2 or 3 days ago.
Thanks!

[a_canadian]

Properly designed K baffles 'work' the gas flow more aggressively than cones, causing both deflection and turbulence at the face in the hemi-toroidal section carved there, and through cross-bore jetting they move flow across the main bore to not only expand into the outer volume, but also to further deflect that main stream of pressure. The result is a much more zig-zagging flow of pressure than one finds with most other types of baffle. As such, K baffles may cause more POI shift than other baffle types. Of course all these are just generalizations. Specific impacts on suppression efficiency and POI shift will vary from baffle to baffle, suppressor to suppressor, depending on relative quality of engineering of both the baffles and the whole system.

[GTS01]

OK so the more I'm reading the more I think I had what a K baffle is wrong. when I typed my questions above I was thinking K baffles were baffles that were notched. I've been reading for the last couple hours and I believe that was an incorrect assumption. Now I'm assuming a K baffle is a baffle that has a main cone with another reversed cone on the back side of it. Is this correct?

I haven't done a super ton of looking yet but it would be nice to have a newbie thread with some definitions. K baffle, mouse holes, notching, scooping, D**** holes... I've been reading for a couple hours trying to figure out what everyone is talking about and trying to get a grasp on the theories. It seems there is more of an art than a science to building these things. Seems it's easy to make them relatively quiet. But it's hard to maximize performance and accuracy.

I hate to hijack this thread with more newbie questions so if I need to just start a new one let me know and I'll do so. But I have a couple legal questions. So obviously you've got to get your tax stamp to build a suppressor. But I see everyone saying you can't do any R&D. I see people build suppressors that can be taken back apart for cleaning, inspection etc. Can you not destroy baffles and build new ones to put in the same suppressor on the same tax stamp so you can try different things while maintaining only one suppressor/tax stamp?

[a_canadian]

Completed builds thread. Lots of links.
viewtopic.php?t=79895

Baffle terminology discussion:
viewtopic.php?t=92684

[fishman]

GTS01, your original assumption about the baffles reflecting and catching the sound is incorrect. Silencers don't kill or hide the sound of a gunshot, the prevent it from ever happening in the first place. They do this two ways, by allowing the gases to expand and slow down, and by cooling the gases before they leave the silencer, therefore reducing the volume of gases leaving. K baffles do a great job of slowing down the gases by creating a ton of turbulence in the can, especially with low pressure rounds.

Start your own thread and there'll be a bunch of guys willing to answer your questions. The more info you give us of what you want/need the more we can help.

***READ THE COMPLETED BUILDS THREAD*** There is so much information there.

[GTS01]

Thanks for the info. My original thought was like the diagrams of the Flowmaster mufflers where they show the baffles reflect the sound waves around into chambers that cancel them out while allowing the exhaust to flow out. Obviously these are different applications but trying to accomplish similar things. I've started in on the build thread but it's very long and a lot of info so haven't gotten to far yet.

[a_canadian]

The problem in comparing mufflers to suppressors is primary one of pressure differences. A muffler pushes sound around at pressures barely higher than atmospheric. A rifle suppressor can deal with pressures well above 100x that, in some cases 1,000x., and for extremely brief intervals. The same physics don't apply. It's not just the same thing sped up, as gases behave differently at such radically different pressures.

[fishman]

For those who were wondering: the k baffle orientation didn't matter much.

I shot it dry today, then wet (lithium grease) with ks aligned, then wet with ks alternated.

Dry it was definitely hearing safe, but not THAT quiet.

Wet it was Hollywood quiet. Maybe a touch quieter with the Ks aligned VS alternated.

[John A.]

HA HA HA.

I bet the lithium grease was smokey as hell and got into places even on the other end of the silencer where you didn't have it at LOL

Here's a suggestion that I think you could/should try. I think it would help.

Use copper chore boy to wrap in the recesses. You can use a copper wire to tie around the copper scouring pad to keep it in position and so it don't just try to unwrap when you're pulling the baffles out to clean them.

Put the chore boy where I highlighted in red on the outside of the skirt on all of the baffles. Not just the few I highlighted. Clean all that grease off of everything first. That stuff gets everywhere.

[a_canadian]

Wire mesh in the first few voids is great, providing lots of surfaces to reflect and absorb sound. But lithium grease makes it a breeze to clean the baffles if one cleans frequently, before it all gets burned away and/or shot out the muzzle. Dirty as heck to look at, but who cares, just use some scrap of cloth to wipe it all off. Only lasts a short while though. Swabbing a bit into the back baffle after every couple of mags can help a lot with that.

[fishman]

lithium grease makes it a breeze to clean the baffles

Bingo

I'll have to try metal mesh around the baffles. I still haven't tested water or wire pulling gel in it yet.

[John A.]

Not just any mesh. Stainless would be a poor choice.

I mentioned copper on purpose

[a_canadian]

Where have you sourced pure copper mesh scrubbing pads? All the copper-looking ones I've found are just copper plated stainless, with magnetic properties so not very 'stainless.'

[John A.]

Even the scotch brite are not solid copper, but they are copper coated so they're more resistant to the heat.

I've always heard not to use stainless for several reasons.

1. Dissimilar metals like steel and aluminum suffer from galvanization faster than copper and the copper tends to tarnish rather than the baffles.

2. I've always seen it pointed out that stainless steel will combust. Something you don't want to happen inside of your can. especially combined with titanium. Another combustible metal.

steel wire on fire

https://www.youtube.com/watch?v=PNWONhxILFA

titanium on fire

https://www.youtube.com/watch?v=J_oUiXliV_Q


So, I use copper mesh. Even if coated.

[fishman]

I'd have to clean them real well then shoot only a couple shots through it. It was just too dirty to tell much of anything. The lithium grease didn't help I'm sure.

Actually shooting a few dozen rounds through it would be more likely to tell the true tale. Patterns emerge after a while. Especially useful in analysis of flow into the expansion volume outside the K baffles. If after 30 or 40 shots there's still very little evidence of firing outside the skirts, you could surmise that the porting wasn't quite doing its job. From the tiny bit of that area I can make out in your pictures it seems there are some dark spots appearing, so that's good. At a guess it seems that the angled drill approach has taken the waist port out of the equation a little however, as the exit hole is quite far from the bore line. That's why dipping in from the front of the baffle with a round-nosed or flat-nosed mill bit is generally preferred, keeping this port very close to the area of highest pressure and thus forcing more gas expansion into the outer volume. But hey, if the suppressor is effective, if you're happy with it, then it worked.

The front faces of the baffles, on the side opposite the scoop, have the carbon and grease blasted away while the scoop side is dirty. this tells me that the scoop cuts and waist geometry are doing their job of deflecting the main flow of gas off the line of the bore. Again, the inside of the tube was dirty, the waist ports are doing their job of filling the coaxial area. Maybe the ports would trap gas better if I made them smaller, but they're doing their job.

[a_canadian]

That's all anyone could hope for, nicely done!

[doubloon]

Even the scotch brite are not solid copper, ...

I think Chore Boy are ~100% copper or as close as you can get.

[T-Rex]

Even the scotch brite are not solid copper, ...

I think Chore Boy are ~100% copper or as close as you can get.

From their website:
"Chore Boy® Ultimate Copper Scrubbers are created with pure copper using the latest machine knit procedures. - See more at: http://www.choreboyscrubbers.com/chore- ... HYxhW.dpuf"

[John A.]

Fishman, did you ever try wrapping the skirts with wire mesh yet? You may be well pleased of if you tried it.

[fishman]

Fishman, did you ever try wrapping the skirts with wire mesh yet? You may be well pleased of if you tried it.

I've been busy, Ill get around to it eventually

[jimmym40a2]

Nice build!

[doubloon]

Yes, it is a nice build.

I keep trying to ignore this thread because if I keep reading it I'll end up building one.

[fishman]

Yes, it is a nice build.

I keep trying to ignore this thread because if I keep reading it I'll end up building one.

I take that as more of a compliment than anything anyone has said so far.

If you do something similar, save yourself the headache and do a pistol length gas system.