Given the popularity and effectiveness of the little 5" Sparrow, would the Spectre become less desirable if SilencerCo ever made an additional larger Sparrow offering at 6" providing it had greater FRP reduction?
Would a special inch longer Sparrow lose most of the FRP or need a little redesign tweaking to get that FRP eliminated?
Would the Spectre have anything in favor over the hypothetical 6" Sparrow

The Liberty TL already does that and has a tapered bore with less blowback.

The Spectre is easy to clean , cheaper, and isn't going anywhere until Henry pops back up and kicks Silenserco's ass.

Machine an adapter and mate the two in to one and be super stealth guy.

The FRP is a function of it being a monocore, not the length. A larger version might actually have more FRP given the additional volume.

Another [ to be taken with a grain of salt ] anecdotal
design modification was to roll a coil of #16 bronze mesh (.018" Wire Dia.) like a hollow
Tootsie Roll* and place in the expansion chamber. The supposed
idea was that like a catalytic converter the hot gases would quickly
heat up the mesh and the increased surface area would then burn
off more of the unignited particulates, thus diminishing FRP.



* Wiki Korean 'Police Action' factoid:

"During the Battle of Chosin Reservoir in 1950, mortar sections under the United States Marine Corps
started to run out of mortar rounds. The radio men of these sections started requesting more rounds.
There were too many nearby enemy anti-air emplacements however, and the risk that they might lose
any airlifted supplies was too great, so they had to wait. After two days of waiting, all the mortar sections ran out of rounds.
At this point the risk was taken and supplies were dropped anyway.
When the troops found the crates of mortar rounds, they found the crates were instead filled with Tootsie Rolls.
The cause of this error was that a supply specialist did not know
that the codename for mortar rounds was "Tootsie Rolls", and instead ordered hundreds of crates
of Tootsie Roll candies instead of mortar rounds."

[quote="Historian"]Another [ to be taken with a grain of salt ] anecdotal
design modification was to roll a coil of #16 bronze mesh (.018" Wire Dia.) like a hollow
Tootsie Roll* and place in the expansion chamber. The supposed
idea was that like a catalytic converter the hot gases would quickly
heat up the mesh and the increased surface area would then burn
off more of the unignited particulates, thus diminishing FRP.



I don't see how that would eleminate FRP. 1st,There would be no heat for the first round. 2nd, FRP comes from the oxygen in the suppressor not from unburned powder.

I've seen and heard Liberty's Kodiak Ultra, Spectres, Sparrows, and other cans on a whole myriad of 22 hosts. I'm coming to the point that I think there is simply a level of "bullet noise" that can't really be brought down any further holding bullet size and velocity constant. Even very long barrel 22's I've heard(24"), which should diminish a good bit of the pressure before even hitting the suppressor, sound about the same as 16" barreled guns.

Hardly any sort of final proof, but I have had some experimental experience which backs that up on a PCP (air) pistol which I have set up as a carbine. Unsuppressed, the pistol is about as loud as a semi-auto pistol shooting subsonic .22"LR without a suppressor. I've put various monocore and K baffle suppressors on it, and the quietest I was able to make it was a very tolerable level about like a weak spring air rifle, using a series of 8 plastic K baffles of a sort of stubby, or barrel shape, in an 8" x 1" aluminum tube. Each cone was stepped inside and out. Cross-bore vented, with about 25" of the air volume outside the cones. Faces detailed nicely to scoop air pressure away from the bore. Very quiet. Then I wanted more, so I fitted a 1.5" aluminum tube to it with a plastic adapter and used a 6" plastic monocore in that section, a monocore which had performed almost as well as the K baffle suppressor on its own. I was expecting ultra-quiet. What I heard was incremental; perhaps 1 or 2dB quieter, but not really very significant. And since handling the carbine became clumsy with such a dramatic increase in length I gave up on the thing. Seems there's a limit to how quiet I can make it and going to a setup which looked like a cartoon telescope isn't worth the slight improvement.

vike wrote:Given the popularity and effectiveness of the little 5" Sparrow, would the Spectre become less desirable if SilencerCo ever made an additional larger Sparrow offering at 6" providing it had greater FRP reduction?
Would a special inch longer Sparrow lose most of the FRP or need a little redesign tweaking to get that FRP eliminated?
Would the Spectre have anything in favor over the hypothetical 6" Sparrow

Been there done that. The shorter Sparrow version is quieter.

https://www.youtube.com/watch?v=LmtC6uFY4Gk

Fireman1291 wrote:

vike wrote:Given the popularity and effectiveness of the little 5" Sparrow, would the Spectre become less desirable if SilencerCo ever made an additional larger Sparrow offering at 6" providing it had greater FRP reduction?
Would a special inch longer Sparrow lose most of the FRP or need a little redesign tweaking to get that FRP eliminated?
Would the Spectre have anything in favor over the hypothetical 6" Sparrow

Been there done that. The shorter Sparrow version is quieter.

https://www.youtube.com/watch?v=LmtC6uFY4Gk

Super demonstration! Thank you for inviting us over.
Impressive suppressor from an as always impressive company.

Thank you.


Best.

Hey Fireman1291; if you're hanging around, could you offer a measurement of the bore size on the replacement Sparrow core? In your video it looks fairly substantial, perhaps a larger than average clearance for .22". From pausing at a couple of frames and staring at it (not exactly a way to measure anything) it looked like 0.30" or so, is that right?

a_canadian wrote:Hey Fireman1291; if you're hanging around, could you offer a measurement of the bore size on the replacement Sparrow core? In your video it looks fairly substantial, perhaps a larger than average clearance for .22". From pausing at a couple of frames and staring at it (not exactly a way to measure anything) it looked like 0.30" or so, is that right?

Your question initiated my looking up in the archives various diameters
for .22 cans. The largest that I found was the scribbled notes made in the 1960's.
Surprisingly the specs for the 1930's .22 British Parker Hale MM I was
.030". Guess the engineers at PH correctly erred on the side of caution.

The figure of merit given by the gray beards here is dim ( bullet ) + .060, which
for .22 would be .280. It would be interesting to know what you and others use or have
for your cans.

Best.

I've used 0.25" on all my trials with a .22" airgun, so 0.030" diameter larger than the projectile. That's with baffle stacks between about 5" and 9" and a hand tap mounted in the tailstock of my very tiny toy lathe, turning the rear caps (mostly delrin or other plastics, a few in 6061 or 7075 aluminum) in the chuck by hand, slowly. It's mostly worked. Botched alignment in a few. I know of some .22"LR cans with the same bore size. A bit snug, but if accurate it works well.

I asked regarding the bore for this one being perhaps as large as 0.30" because by all reports the new core is very efficient. Makes me wonder if I ought not to try a larger bore, just to compare. Perhaps a snug fit isn't the best for suppression? Or perhaps the Sparrow has a tighter bore than that and I'm just seeing it wrongly in the video.

I called SilencerCO a few years back and asked them if they could make me a 7 inch Sparrow, they explained to me that it wouldn't make enough difference in sound, they said its the perfect size for the lowest suppression level they could reach.

gunguy wrote:I called SilencerCO a few years back and asked them if they could make me a 7 inch Sparrow, they explained to me that it wouldn't make enough difference in sound, they said its the perfect size for the lowest suppression level they could reach.

I'm new to suppressors so forgive the ignorance but how does more room for gases to expand and slow not equal less sound? Isn't that why integrated suppressors generally perform better than detachable cans?

JasonNC wrote:

gunguy wrote:I called SilencerCO a few years back and asked them if they could make me a 7 inch Sparrow, they explained to me that it wouldn't make enough difference in sound, they said its the perfect size for the lowest suppression level they could reach.

I'm new to suppressors so forgive the ignorance but how does more room for gases to expand and slow not equal less sound? Isn't that why integrated suppressors generally perform better than detachable cans?

Point of diminishing returns. Cans work based on pressures, once it lowers below what drives the baffles the gas doesn't really do much but exit the can.

Integrals generally perform better because they bleed off the gases to lower the pressure, allowing for smaller cans and better performance.

Bendersquint wrote:

JasonNC wrote:

gunguy wrote:I called SilencerCO a few years back and asked them if they could make me a 7 inch Sparrow, they explained to me that it wouldn't make enough difference in sound, they said its the perfect size for the lowest suppression level they could reach.

I'm new to suppressors so forgive the ignorance but how does more room for gases to expand and slow not equal less sound? Isn't that why integrated suppressors generally perform better than detachable cans?

Point of diminishing returns. Cans work based on pressures, once it lowers below what drives the baffles the gas doesn't really do much but exit the can.

Integrals generally perform better because they bleed off the gases to lower the pressure, allowing for smaller cans and better performance.

And why can't screw ons bleed off gases just as well? Just trying to understand the mechanism.

Also, what is it about monocores that causes FRP? The shape of the blast baffle or something else?

Not all integrals involve barrel porting, but many of the more successful (in terms of making firing quieter) designs do. Barrel porting tends to reduce projectile velocity at the muzzle, leaving less work for the can do do in reducing volume. That is, provided the barrel ports are covered by the can and the rear of the can is sealed reasonably well to the barrel of course. In extreme cases, in .22" for instance, ports can be cut to within 4" or even closer to the breech. In the case of a Ruger pistol for example this can leave anywhere from an inch to several inches (depending on the barrel used) for ports and over-the-barrel air volume to capture the initial, highest pressure gases to expand, dramatically reducing the volume even if there's no can in front of the muzzle. Add a short K baffle can of good design and you've got a pop gun. Now if you take this further and fully port a rifle barrel, leaving a lot more room for expansion over the barrel, the amount of pressure left at the muzzle to be trimmed by a short can is tiny in comparison to an un-ported rifle barrel. Hence the incredibly quiet Thompson Machine 'Operative' for instance. So short answer; no, a direct comparison of what's happening between a screw-on can and a ported over-the-barrel suppressor is not very practical, and the well designed versions of the latter will win in sound suppression every time.

FRP has to do with combustion of a large volume of un-burned powder after exiting the muzzle. If your first chamber (blast chamber) is excessively large, the oxygen present during the first shot will facilitate efficient and loud combustion of that un-burned powder within that chamber, giving the remaining baffles more work to do. And in the case of a smaller can this means a louder initial blast. Of course after this first shot there's little to no oxygen left to help powder burn, at least until it airs out for a while, so successive shots will be quieter and there will be more un-burned powder to build up between baffles. I'm not sure why, or even if, this is something specific to monocores. I suspect it has more to do with many monocores having large blast chambers, while a lot of K baffle suppressors tend to be filled with K baffles more completely, with rather small blast chambers.

It is the baffle designs between the Sparrow and Spectre that cause the FRP issue, not the length.

A 6" Sparrow would make similar in size to the Spectre 2, but performance would still be the same...Spectre 2 having virtually no FRP.