Regulators and plenums

[rash_powder]

So I am struggling to get the correct ring lock too hat I need for the velocity I want from my TalonP.  Mostly having problems with my chrome but that is another topic.

What I am wondering is; is there a correlation between barrel volume and required plenum volume? 

My reasoning -

My 12” .22 barrel is about 7.5cc, and the .25 is about 9.5cc.

So the Huben reg with a 20cc plenum should be big enough since it is more than double the barrel volume?  But, I’m thinking this would give quite a pressure drop by the time the pellet leaves the barrel.  Their 50cc may be better, but at nearly double the cost. 

I’m not looking for monster power.  Just to take down birds, squirrels, and MAYBE a raccoon at 50yds or less.  I’m thinking 750fps should be enough.

I now have a compressor so fills aren’t a problem, but toting the gear around not worthy so would rather not waste air. 

So, in a nutshell, which plenum and why?  Please keep reasons better than because bigger is better.

Thanks!

[HunterWhite]

I seem to recall that the rule of thumb was 1CC per FPE. I know that is mixing measurement systems, but it was presented by much more educated airgunners than me.
If you’re Talon P gets 50 FPE then 50 CC sounds about right.
Hopefully the expert can read this and give you the best answer.

Hunter

[Back_Roads]

 My guesstimate the 20cc should give you the 750 or a bit more FPS, 50cc would waste air in a 12" barrel. What reg pressure do yo plan on using ?

[rash_powder]

My guesstimate the 20cc should give you the 750 or a bit more FPS, 50cc would waste air in a 12" barrel. What reg pressure do yo plan on using ?

I'm not sure yet - I've to get my misbehaving chronograph to behave.  I shot it some time ago and its not been used (i've not shot anything in a few years) since.  I think it may be leaking light, but cannot say.  need to tear it apart again and troubleshoot.

[Back_Roads]

 When I regulated my .20 cal Escape UL I found 2200 to be a good place to start. 1800 seemed a bit weak with a small plenum, not a Huben product that I used.