Hi Keith! Would you be running these moderators attached to the shroud, or directly to the muzzle? I ask for two reasons:
1) shrouds will significantly improve sound attenuation
2) my testing suggests that, on shrouded and relatively low-flow guns, larger diameter moderators may not actually perform as well as their skinnier counterparts of equal length. And this really seems to be a strong trend.
It is a bit of a read, but I hope this helps:
https://www.airgunnation.com/topic/fx-crown-bespoke-moderator-tesla-gas-diode/page/5/#post-453278 *edit*
For those looking for the spark-notes version, here is the breakdown chart. All of this was tested on my FX Crown .22:
So you are saying the smaller tanto is better than the sumo? 71.2 vs 108 is a big difference. Wanting to get one for my impact 25 cal. Will be screwing in on the shroud. So the tanto will be a better deal?
So far as I can tell, it is not so simple as one moderator being better in absolute terms than another, particularly if you restrict the architecture type to just the "hair curler, felt, and washer baffle" format. This category includes the 0dB, Hugget, Clague, and Donny moderators, which are all the same in that it is basically a wrap of felt around the outside, some sort of structure to hold that felt around the perimeter, and big flat baffle obstructions in the middle, usually two or three of them.
My data indicates that, in ~32 foot pound systems, smaller diameter and longer tubes will perform better, all else being equal, than an identical architecture of larger diameter. I can only assume however that, if you for example have a double-bottle FX Impact with extended plenum running much higher air outputs, all moderators will be louder in absolute term but in relative terms the larger volume designs will begin to gain the upper hand in terms of sound attenuation.
The OP however very specifically asked about two guns which are .177 and .22 running in the low 30 foot pound range and below, which suggests he is in the power category where the Sumo and Ronin will perform worse than the 0dB, Tanto, Belita, etc.
You, shinyknight, running an impact in .25 caliber, I can't as specifically speak to because I don't have a test platform in that performance range. Actually, .25 in general spans a rather large performance range anyway, as some people are running light .25s which are no more air consumption/KE than the high end of .22s while others are all the way up to slugs running 100FPE. So I can't suggest a specific moderator, because I don't have enough data, but I suspect that a .22 caliber Tanto won't be the best choice.
I realize that doesn't answer your question, but I hope it provides at least some insight to better inform your decision.
I hope that helps.
