I totally agree with all of you guys! I'm really interested in this stuff and have done some basic testing to the best of my ability with the equipment I have on hand. I've also discussed this stuff in great detail with Neil Clague and to a lesser degree STO from this board. I just wanted to share a few things. Ackuric, sorry some of this stuff is the same as you just posted, apparently I was writing it when you posted. I agree with you as you can see.
I own a few silencers {6 total - 3-Clague, 2-DonnyFL(Shogun Sumo) and one made by STO} and have tried some testing with my boys. We've found that the end result really depends on the gun/silencer combo. My boys and I have screwed all of the silencers on all of our guns(Gauntlet .22, Crown .25, Bantam .22, Hatsan AT-44 .25 and Streamline .25) and they all sound different on different guns. Internal volume and/or baffles that reroute gasses or divided the silencer into separate chambers do the most to quiet the report. Baffling material has a small effect on the sound signature but we found it was negligible. I have a Neil Clague silencer(8") with nothing inside of it except a tiny bit attached to the inside walls and it quiets my Crown the most followed by the DonnyFL Shogun and Sumo which both have chambers and baffling material. My sons Bantam is quietest with a three chamber Clague design(8") again with almost no baffling material, followed by the Shogun and Sumo which both have baffles and material inside. The Streamline is best with the DonnyFL Shogun, Sumo or either Neil Clague design, they all sound about the same. The Gauntlet is most quiet with the Clague single chamber design but all of the silencers made it very quiet. The Hatsan also benefited best from the Clague single chamber design. It was loud to begin with.
Neil is my neighbor/friend and we have discussed this stuff in great depth. Neil is a believer in the benefit of internal volume but makes plenty of silencers with baffles and a little internal sound reducing material(Minimal amounts on the interior wall) depending on the gun it's being used with. He definitely knows what design works best with what gun. All of his silencers are made to order, so he's making it for your particular gun and caliber. He makes them out of aluminum, titanium, or carbon fiber. STO made me a silencer that is much shorter than any of the others, it's very light, looks superb and sounds phenomenal. It's made of carbon fiber and the internals are made with a 3D printer. It's not the quietest design but it definitely has the lowest pitch which is perceived as quieter. He told me that he didn't make it to be the quietest, he made it to be small, light and just get rid of the Crown's bark...he accomplished his goal. He could have easily added a 1"-2" expansion chamber at the front, it would have still been light, short and it also would have been the quietest on my Crown! When used on my Crown, if I extend my shroud just about 2", which still makes STO's design the shortest(gun's overall length) it is the quietest on my Crown also a very low pitch. That's a combination of the volume of my shroud and the crazy cool internal design of STO's silencer. It's design has all kinds of holes, tubes, and baffles that reroute gas for optimal sound deadening performance and pellet stabilization. Again, no baffling material just a design that redirects and slows the gasses. It's called the Tesla Gas Diode Moderator. Do a search on AGN, you'll find here. On a side note, STO's design is the only one made specifically to screw on the shroud of the Crown so we couldn't test it on the other guns, I think it would have worked very well.
Silencers are much more complicated than whether the design has baffles, internal baffling material or just internal volume. The internal volume and addition of chambers are the two best features for deadening the report of an air gun. We also know that caliber, air volume and velocity contribute to the report of an airgun. Another factor I hadn't thought of before talking to Neil is the composition of the material being used for the silencer itself. Titanium, aluminum, carbon fiber and all of the plastics and composites being made into silencers these days all have an affect on the pitch of the silencer. This is why Neil adds a thin layer of material around the inside, to deaden the high pitch ting sound of aluminum, not to absorb some of the report. One more thing to consider is that silencers designed for powder burners generally are not the best design for air guns. As many have already concluded, volume is more important for air guns. From our testing, we determined that internal volume and baffles to slow or redirect gasses are the two biggest factors in reducing the sound signature. One of the biggest surprises to my boys and I was when we screwed the Clague silencer with no baffles or baffling material on my Crown, it was the quietest by far. When we screwed it on my son's Bantam Hi Lite, it wasn't nearly as quiet. We screwed the Clague design with two internal baffles/3 chambers on My son's Bantam and it was the quietest... but much louder on my Crown. They are exactly the same size/internal volume and design other than that one has 2 baffles/3 chambers and the other has one large chamber. They sounded completely different on each of our guns! That one has us baffled! lol
My testing is not anywhere near perfectly scientific but all of the guns and silencers were tested the same way to get the best results possible. We used 3 simple dB meters on our phones, placed at 3 different spots, in front of, to the side of and behind the gun/silencer being tested. We also just listened because perceived sound can be more important than the dB in how we hear the report. Also, the silencers are all made for .25 caliber guns so you may get a tad better sound reducing performance if you use a .22 design with your .22. I've had pellet clipping issues with my .22's so I just decided to buy .25 silencers so I can interchange them all. The opening at the muzzle end of my various silencers range from 0.315"-0.330"
I wanted to share the results of our simple testing and the discussions I've had with Neil and STO. I don't want to sell Donny short here though, I just haven't had in depth discussions with him like I have Neil and STO. His designs are great, very quiet, look awesome and his customer service is absolutely top notch. When I was getting ready to buy a Sumo from him directly, I texted him at 8:30pm Pacific time, 11:30pm East Coast time and got an instant response, I bought a silencer, he gave be 10% off just to be cool and I had the silencer in just 3 days...he's in Fl. and I'm in Ca. He really is a good guy and makes a great product, you can't go wrong with a DonnyFL design! I know that the Huggett has a great following and I've heard Wiehrach silencers do a great job too. Recently AOA started selling Trident moderators which look really cool and have internals that look similar to many other silencers out there. One smart design feature of the Trident is that the internals are made to blow apart if used on a powder burner. That way, there is no possible hang up's with the law for having an illegal silencer. A smart design! I've heard they work great too. I just don't have any of these silencers to try.
I'm not trying to sell anybody's products here and I'm not trying to give props to one over another. Neil, STO and Donny are all great guys and make great products I just wanted to share what I've learned from Neil and STO and also share the simple testing results we got with each of the silencers on each of our guns to help answer the question... I think the most important factors in reducing report are... #1 internal volume, #2 baffles/chambers, and to a lesser degree #3 baffling material, #4 material being used to make the silencer.
Here are some of the silencers. I don't have pictures of them all.
Stoti
