DonnyY moderators..Do you still need to size up?

I do for all mine. Not sure it's necessary tho. The idea is it helps prevent baffle strikes. I do for my powder burner silencers as well for same reason.

if the barrels are centered and silencer is made correctly id sure use a 22 for a 22 sound and dirty air makes accuracy differences just my opinion 

I would check with Donny; they are super receptive to questions and quick with answers. 

My experience is limited to two examples, but I am literally right now dealing with DonnyFL customer service re: a SUMO that was purchase for a .25, (rated for .22 and .25) but before I received it, I tried it on three separate .22 and it's not working. I understand now that it's due to baffle collision, but I did not understand what was going on when I decided to try it on other rifles.



Anyway, point being, in one case, even with it being "one size up" for .25, it failed at .22

On the other hand, my .22 rated Tanto is working fine on the same .22 rifle I first tried the SUMO on.

It depends… mostly on your setup: if you have a shroud, and then an adapter, and then mount the moderator, chances increases you get clipping. To prevent many customers complaining (as far as I can remember) Donny decided to advise to go one size up: less risk that way.

But smallest diameter hole also helps with reducing sound. So if you setup is straight, and for example you attach the mod directly onto straightcut barrel, then I always get the smallest diameter.

oyeah, if availble, you might try the Weihrauch xl…

The last couple Tanto moderators I’ve bought in .22-.25 definitely have a larger bore size than my old one. They are now oversized for the .25 and is quite a bit less effective on a .22 than my old one. I wish the option were still there to buy the old sizes but I understand they are trying to minimize returns due to misalignment on questionable quality manufacturing from airgun makers. 
Since the bore size change I would recommend NOT sizing up, and sticking with what Donny has designated for each caliber. He has already done the over sizing for you at this point. 

I've never had a baffle strike with any of mine with the same caliber moderator. The question is stable is the projectile when it leaves the support of the rifling? Slugs/pellets can act like arrows until they settle down and stabilize.

A simple test would be to shoot point blank a piece of cardboard and look for any sign of keyholing. Otherwise, something would have to be loose and out of alignment for a strike.

I've never had a baffle strike with any of mine with the same caliber moderator. The question is stable is the projectile when it leaves the support of the rifling? Slugs/pellets can act like arrows until they settle down and stabilize.

A simple test would be to shoot point blank a piece of cardboard and look for any sign of keyholing. Otherwise, something would have to be loose and out of alignment for a strike.

Click to expand...

I haven’t had issues with baffle strikes either but with shrouded guns where the moderator is threaded onto the shroud 5 or more inches away from the actual muzzle of the air rifle it increases the chance for manufacturing tolerances to be off enough to cause a misalignment. If a moderator is threaded directly to the barrel it has a much better chance of alignment and even then many Airgun barrels do not have bores that are perfectly centered in the barrel. Like you I’ve been lucky to not have any with any drastic misalignment issues but I imagine a person new to the airgunning world wouldn’t immediately realize the problem wasn’t the moderator but instead the shroud is askew...and this would result in the guy that sells the moderators getting returns for “defective” units when they weren’t defective at all. Thus the moderator bore sizes continue to increase. The inner bore size on the new fatboy is very big. 
Edit*** I did damage a .22 sumo once. I had swapped out my .22 full length barrel on my condor for the SS .25 barrel and completely forgot about it. I fired a 52 gr .25 boat tail through it and it never made it through the sumo.