Moderator bore diameter- Comment to Ted's Holdover

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hi-vel

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May 16, 2015
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In one of Ted's later videos he commented about the bore diameter being noticeably larger than the actual bore of the barrel. This is correct and I agree with his statement that it is desirable. This may make some shooters wonder about the manufacturing, but in reality it shouldn't.

My current experience is with the SIG series of suppressors, installed on MCX .223, 11-inch barrelled rifles. Ever shoot a straight 11-inch .223 (Un-suppressed)? Brother, that is LOUD. With a suppressor it is approximately equal to a 22LR (mid-range load). 

The bore of the suppressor is actually fairly large compared to the muzzle/bore of a standard .223. .224" .vs. .300" (measured with a caliper). Fortunately, we had a SIG rep going through the next day. He took the time to explain not only the simple baffle system they were using (and some of their proprietary mfr'g methods), but also explained that they had shot with clearances from .002" on up, before they decided on their current configuration. 

The conclusion was that due to ammunition variances and probability of an unstable bullet entering the suppressor off-center or wobbling, a clearance over bore diameter gave a minimal increase in decibels, but would continue in service much longer. The specific numbers SIG referenced were in the range of 2-7% depending on ammunition variables, for 3-4 calibers over actual bore diameter. Yes it is louder, but the reliability is exponentially greater- an acceptable trade off. And of course if you don't get baffle strikes, accuracy also continues at original levels. (More or less what Ted was saying). An acceptable trade off.
 
I have talked to Donny FL and he recommends 1 Cal. Over . IE. 30 Cal for 25 . 25 for 22. And so on. It's the advice of manufacturer.works for me. I hate math!
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This statement always kind of baffles me. If this what he recommends why doesn't he just manufacture them to these specs? Based on his thinking a supressor made for a .177 is not recommended for any normal caliber.
 
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I have talked to Donny FL and he recommends 1 Cal. Over . IE. 30 Cal for 25 . 25 for 22. And so on. It's the advice of manufacturer.works for me. I hate math!
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This statement always kind of baffles me. If this what he recommends why doesn't he just manufacture them to these specs? Based on his thinking a supressor made for a .177 is not recommended for any normal caliber.
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My thoughts exactly.
 
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Donny's equipment isn't shooting .223 firearm ammunition, which has a metal jacket slug. He gives us what we want...maximum silence, AND the option of going one caliber larger if it pleases you.

In my world, silence is golden, and a smaller bore has proven over the years to be a quieter bore. If a lead slug or pellet strikes a baffle, there is generally no harm done, except for accuracy. If this problem happens, you can always bore out the offending baffle with a rat-tail file, or drill bit.

Personally, when I need "quiet" I'm not concerned about a potential baffle contact, I'm concerned about the neighbor's calling the police and complicating my life. I like to shoot. I can't always get out to the privacy of the woods. Be it alley/garbage can rats, pigeons, possums, raccoons, or armadillos, there are occasions when I trust my aim more than an open can of poison.

That's my take. Your mileage may vary...it generally does.



Hoot
 
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Donny's equipment isn't shooting .223 firearm ammunition, which has a metal jacket slug. He gives us what we want...maximum silence, AND the option of going one caliber larger if it pleases you.

In my world, silence is golden, and a smaller bore has proven over the years to be a quieter bore. If a lead slug or pellet strikes a baffle, there is generally no harm done, except for accuracy. If this problem happens, you can always bore out the offending baffle with a rat-tail file, or drill bit.

Personally, when I need "quiet" I'm not concerned about a potential baffle contact, I'm concerned about the neighbor's calling the police and complicating my life. I like to shoot. I can't always get out to the privacy of the woods. Be it alley/garbage can rats, pigeons, possums, raccoons, or armadillos, there are occasions when I trust my aim more than an open can of poison.

That's my take. Your mileage may vary...it generally does.



Hoot
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I’m pretty sure we are talking Air Guns here not PB
 
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I think the biggest reason for the larger bore moderator is the variables of the bore to moderator being concentric. If the moderator was made for the particular barrel with matching threads. The diameter of the bore of the moderator could be only a couple thousands larger. But when making moderators that are almost generic with thread adapters and such. We need a bigger hole.
 
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OldSparky and Funshine- You are absolutely right, and, it (the hole) really doesn't matter within reason is honestly the point... ;-)

Airgun .vs. PB (powder burners)- I kinda assumed here that everyone would recognize the application of PB to the lesser pressure airguns. The PB gases simply have more energy, thus making them faster and more violent. General gas flows and reactions can be used to build models up thru some of the hyper-energy levels.

Hoot and HatMike- Absolutely no complain with Donny's product. The man builds what he is comfortable standing behind and obviously is successful doing it- a very nice quality product and I wish them continued success. My son shoots Donny's and loves them.

Hepotter- I learned something new, Donny's is willing to accommodate different bore request- I didn't know that. Cannot argue with anything of Donny's I have seen.

This thread was created in response to Ted's observation, which was parallel to my experience/exposure in the PB's.

Thanks to all for their thoughts and input. Have a great week! Hi-vel
 
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I think the biggest reason for the larger bore moderator is the variables of the bore to moderator being concentric. If the moderator was made for the particular barrel with matching threads. The diameter of the bore of the moderator could be only a couple thousands larger. But when making moderators that are almost generic with thread adapters and such. We need a bigger hole.
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^^^This^^^



when I make my mods/ shrouds I do so with them fitted to the barrel that is centred in the lathe, typically I make the first baffle hole only 0.5mm (19 thou) larger than pellet size, subsequent baffles and end cap are 0.75mm bigger (30 thou)







Bb
 
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