300 BLK design

[fishman]

Criticism on my first form 1 design would be appreciated. this will be a 300 blk silencer for an AR with a 10" barrel. priority one is subsonic load performance but i'd prefer if it was able to handle supersonics.

the tube and endcaps are 316, the first two baffles are 17-4, and the Ks and spacers are 7075.
1.625" OD (fits underneath YHM handguards) 11" OAL

[delta9mda]

port in parallel to bore (not the angled bore thru) for the port that leads to around cone. look at the tirant etc k's.

[fishman]

port in parallel to bore (not the angled bore thru) for the port that leads to around cone. look at the tirant etc k's.

why does that help performance? i figured that was just a cheaper way to manufacture them.

[CMV]

port in parallel to bore (not the angled bore thru) for the port that leads to around cone. look at the tirant etc k's.

why does that help performance? i figured that was just a cheaper way to manufacture them.

Draw it both ways & look what happens to the 'little sharp pointy part'.

I'd suggest something other than AL - even 7075 - for the K's for 2 reasons. 1. 300BLK subs are absolutely filthy (at least mine are w/ A1680 & some of the commercial) so it's nice to throw the guts in the ultrasonic. 2. Questionable longevity if you're shooting a lot of high velocity ammo. The subs are Hollywood so you'll probably be like most of us & feed it 90% (made up stat) subs, but the HV quiets down a good bit as well so there is potential to really like that as well.

I don't know how well K's work vs 60° smooth cones, but I know the cones will get it Hollywood.

[Bendersquint]

For a 300BLK I would higly recommend a variant of the cone baffle, will perform much better than a K baffle.

[fishman]

I'd suggest something other than AL - even 7075 - for the K's for 2 reasons. 1. 300BLK subs are absolutely filthy (at least mine are w/ A1680 & some of the commercial) so it's nice to throw the guts in the ultrasonic. 2. Questionable longevity if you're shooting a lot of high velocity ammo. The subs are Hollywood so you'll probably be like most of us & feed it 90% (made up stat) subs, but the HV quiets down a good bit as well so there is potential to really like that as well.

I don't know how well K's work vs 60° smooth cones, but I know the cones will get it Hollywood.

thank you for the input.
i hadn't considered the unltrasonic cleaner. i might make it all stainless for that reason. ive never machined titanium so i dont feel like attempting to make titanium Ks for my first silencer would be a good idea.

Ive read that K's work better for subsonic 300Blk while cones work better for supersonic 300Blk. (just what ive read, i have no experience with 300Blk)

[T-Rex]

For a 300BLK I would higly recommend a variant of the cone baffle, will perform much better than a K baffle.

Generally speaking, 100% supers, 100% subs, or a mix of both?
Same given volume/length?

[fishman]

More cones, less Ks, and updated K design. is that better?

[Bendersquint]

More cones, less Ks, and updated K design. is that better?

I wouldn't mix the baffles styles it won't make it better for one or the other.

[Capt. Link.]

I'm old school but am on board with clipped or ported cones.You have recommendations from CMV & Bendersquint I would use that knowledge.

[fishman]

More cones, less Ks, and updated K design. is that better?

I wouldn't mix the baffles styles it won't make it better for one or the other.

my thought process behind that was that Ks are better for low pressure applications and cones are better for high pressure. while 300Blk does have some high pressures, it also has a low charge weight (at least in the subsonic loads, 208gn, 220gn. i stated earlier that subsonic performance is my priority). since the volume of gas is not large due to the low charge weight, the pressure will drop quickly when expanding in the silencer. thats why i had 2-4 cone baffles in my design followed by Ks. I have no idea if this would yield me good results, that was just my thought process.

It seems the concensus is to go with all cones or all Ks. does anyone have any experience with mixed baffle designs? i dont know of any commercially made cans that have mixed cones and Ks. that might answer my question whether its a good idea.

[Bendersquint]

It seems the concensus is to go with all cones or all Ks. does anyone have any experience with mixed baffle designs? i dont know of any commercially made cans that have mixed cones and Ks. that might answer my question whether its a good idea.

Yes, we have tested mixed designs and saw more impact than benefit.

There is a reason why no commercial cans are mixed baffles.

[T-Rex]

For a 300BLK I would higly recommend a variant of the cone baffle, will perform much better than a K baffle.

Are you referring to these types of cones?

[CMV]

https://youtu.be/Mj8lAg2uAGc

This is the video that's in my 30 cal writeup that's probably a few pages back by now. This is mildly clipped smooth cones vs a Liberty Freedom commercial 30 cal can. Same barrel length ARs, same ammo. Not in the video, but the neither of us could tell any difference shooting HV ammo suppressed. I'm sure a meter would show one as better than the other, but neither of our sets of 'calibrated ears' could say one sounded any better than the other.

I'm not saying don't use K's, but am saying here is something you know will work well. There's probably tons of improvement on my design so you could do even better. If it's your first project or you're still developing your machining skills, it's a much less complex build as well.

If you really want to do K's, do a rimfire can. They will shine in that application.

[LavaRed]

What Bender said. Mixed baffles don't offer much benefit, and they complicate manufacture.
Between 45deg. and 60deg. clipped cones should get you in the sweet spot. Ported spacers that are smaller than the suppressor ID offer improved gas delay while also optimizing volume and reducing weight. Spacing is also critical. Note that the gases lose pressure in every subsequent chamber, so that for a given longitudinal distance, a gas particle will travel a lesser distance axially; i.e., the gas will have less tendency to expand. Therefore, the first baffles should be spaced closer, and the spacing should increase towards the exit. Not the other way around, contrary to what most do.
With your projected length and OD, I'd probably have a blast chamber of about 2", followed by some 10 cone baffles starting at 1/2" spacing and gradually increasing to 1" spacing at the end. About 1" OD for the spacers should do it. Endcaps no thicker than 1/4" each. Anything else is a waste of volume.
All steel construction so it can be fully welded and soaked in solvents, and you have a winner.

[Skorch]

Lavared,

Thank you, thank you for all of that information. I do not know your background, but your reply was very informative. I too was going to take this route for a 300 blackout (cones/k baffle). The spacing is particularly interesting. As you stated, people usually do the opposite. Now you are making me question on the cones themselves, something I thought was practically set in stone.

Cone knowledge (myth or real)?:
1) 60deg better performance than radial
2) reduced efficiency mixing cone angles
3) 60deg is the most efficient angle (you stated 45 to 60)
4) More baffles are preferred rather than spacing for low pressure, opposite is true for high pressure

Haven't gained any knowledge on whether cones or Omega design are more efficient.

[LavaRed]

Many different variables influence cone angle. Caliber, projectile velocity, pressure, etc. While I can't tell you exactly what's optimal, cones within this interval of angles have given me, and others, good results. Also, don't forget variable- angle cones, also known as swept cones. You'll notice their surfaces are always angled between these intervals. Now, mixing cone angles, I don't think it would really offer that much of a benefit, but that would have to be measured. I haven't quite gone there yet. But, as stated before, there are baffles with multiple angles in the same baffle, and that seems to work well for certain variables.
More baffles are always better, but there is a point past which reduced spacing doesn't give the gas enough space to expand before it passes the baffle. Hence why increased spacing towards the muzzle is better. Think of the gas in terms of particles. Now, in a gross oversimplification, we will assume that ambient air pressure is zero, and we will assume that ambient air particles have no effect whatsoever on the gas particles. The gas particles will always try to reach a state of equilibrium with the ambient air, i.e., reach zero pressure. To do this, they need to expand. The less pressure, the less inclined to expand, i.e, move away from their initial line of travel, they will be. This effect, if graphed, would not be linear, but rather inverse exponential. Which basically means the lower the pressure, the more space they need to be given to move away from the bore axis. This would also seem to suggest that variable angle cones work best, but I have not tested this hypothesis yet.

Finally, both Omegas and cones have their place. But if you use spacers that are of less diameter than the tube, you should have the benefits of both.

[fishman]

thanks, everyone, for the input. I've heard enough to convince me that cones are the way to go over Ks. (plus then the can would work well on my .270 coyote rifle too. silencers were just legalized here in michigan for hunting last month)

I like the idea of making the spacers smaller diameter than the ID of the tube, that seems unconventional but makes a lot of sense. with this design should i port the cones, port the spacers, or both?

should the cones be clipped symmetrically or asymmetrically? does it matter if asymmetrically clipped cones are rotationally oriented specifically or can they be oriented randomly?

thanks in advance

[fishman]

clipped cones should get you in the sweet spot. Ported spacers that are smaller than the suppressor ID offer improved gas delay while also optimizing volume and reducing weight. ... With your projected length and OD, I'd probably have a blast chamber of about 2", followed by some 10 cone baffles starting at 1/2" spacing and gradually increasing to 1" spacing at the end. About 1" OD for the spacers should do it. Endcaps no thicker than 1/4" each. Anything else is a waste of volume.
All steel construction so it can be fully welded and soaked in solvents, and you have a winner.

like this?

i drew it with equal sized spacers for simplicity.

[Bendersquint]

clipped cones should get you in the sweet spot. Ported spacers that are smaller than the suppressor ID offer improved gas delay while also optimizing volume and reducing weight. ... With your projected length and OD, I'd probably have a blast chamber of about 2", followed by some 10 cone baffles starting at 1/2" spacing and gradually increasing to 1" spacing at the end. About 1" OD for the spacers should do it. Endcaps no thicker than 1/4" each. Anything else is a waste of volume.
All steel construction so it can be fully welded and soaked in solvents, and you have a winner.

like this?

i drew it with equal sized spacers for simplicity.

Spacers to the wall, not coaxial will perform better.

[fishman]

Spacers to the wall, not coaxial will perform better.

how would you recommend I clip and/or port the cones if i make them the same diameter as the tube?

[LavaRed]

clipped cones should get you in the sweet spot. Ported spacers that are smaller than the suppressor ID offer improved gas delay while also optimizing volume and reducing weight. ... With your projected length and OD, I'd probably have a blast chamber of about 2", followed by some 10 cone baffles starting at 1/2" spacing and gradually increasing to 1" spacing at the end. About 1" OD for the spacers should do it. Endcaps no thicker than 1/4" each. Anything else is a waste of volume.
All steel construction so it can be fully welded and soaked in solvents, and you have a winner.

like this?

i drew it with equal sized spacers for simplicity.

Spacers to the wall, not coaxial will perform better.

Now it's my turn to ask. Why do spacers to the wall work better? I mean, if the spacers are heavily ported, wouldn't it make little difference?
Thanks,
Lava

[whiterussian1974]

Spacers to the wall, not coaxial will perform better.

Now it's my turn to ask. Why do spacers to the wall work better? I mean, if the spacers are heavily ported, wouldn't it make little difference?
Thanks, Lava

It will impede air movement into coaxial spaces. But it also impedes return OUT OF coaxial back into boreline.

That's why Omegas work for pistol rds w lower pressure and powder weight. 300BLK subs should be close to .45ACP. Just more gas to trap.

But fast moving jets will exit the can b/f they have time to pressurize coax. So lots of wasted volume.

[whiterussian1974]

Ported spacers that are smaller than the suppressor ID offer improved gas delay while also optimizing volume and reducing weight. Spacing is also critical. Note that the gases lose pressure in every subsequent chamber, so that for a given longitudinal distance, a gas particle will travel a lesser distance axially; i.e., the gas will have less tendency to expand. Therefore, the first baffles should be spaced closer, and the spacing should increase towards the exit. Not the other way around, contrary to what most do.
With your projected length and OD, I'd probably have a blast chamber of about 2", followed by some 10 cone baffles starting at 1/2" spacing and gradually increasing to 1" spacing at the end. About 1" OD for the spacers should do it. Endcaps no thicker than 1/4" each. Anything else is a waste of volume.

While agreeing w most of what you say, I must take exception w 1 aspect b/c you didn't address gas jet velocity. Yes, trapping small packets of high pressure gases early makes good sense.

But, one must consider that gas jets traveling supersonic unpon leaving the barrel will enter Choked Flow conditions and must drop velocity b/f they can spread to fill the OD properly. So, if not enough linear distance b/t baffles, the core of jet will pass through into the next chamber w/o properly expanding to fill the volume.

[CMV]

Now it's my turn to ask. Why do spacers to the wall work better? I mean, if the spacers are heavily ported, wouldn't it make little difference?
Thanks,
Lava

I would think all the way to the wall would win. The gas will want to follow the wall. Let it until it goes as far as it can, then it has to redirect. Interrupting its path with a small spacer as you have pictured is keeping the gas from following the cones wall as far as it can (and losing velocity as it does.) It's going to re-direct either way, so why not let it travel farther before redirecting?

I think this is going to have a greater negative effect on the 'exit end' of each cone. You are taking the fast moving gas that is forced through a tiny opening and giving it a path it wants to follow to rapidly expand, slow down, and then redirect. Let it follow that path as far as it can - otherwise half the cone area isn't 'working' because you put a 'roadblock' where one shouldn't be. Would be same effect as a cone made like this:

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instead of:

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