Larger plenum for Huma regulator??

[Rallyshark]

I was wondering if anyone knows where I can get my hands on a larger plenum or extension for the Huma reg in my .22 Bullboss(same as AT44).  I'm thinking 15-20 ccs more would be the magic number I'm looking for.  Is the plenum for a Huma for a .25 AT44 larger than the .22 plenum?  If so, I wonder if I could just get the .25 plenum?  An extension for my current plenum would be even better, since it would give me easy flexibility to remove the extra ccs if I wanted. 

I recently got the opportunity to add a 30cc extension on a friend's .22 I was tuning, and I was impressed with the results.  I was able to get a slightly better shot count, and with less hammer spring.  I tuned the gun to get a high shot count at 30fpe, so the extra plenum wasn't required to make that power level.  The power potential at the same reg set point went up, which I expected.  With all things left the same(reg set point/hammer spring adustment), and simply adding the extension, the fps went from 890fps to 930fps.  I ended up with about 1.5 turns less hammer to achieve that 30fpe mark.  I think it worked really well for the gun I was working on, because that gun was basically made for power, and all the porting is huge for a .22. 

I'm now thinking it may benefit my highly tuned Bullboss.  I don't think I need the whole 30 ccs extra, but I think a little more may allow me to improve on things a little more.  Anywho, anyone know where I can get my paws on a larger plenum or extension?? 

[Motorhead]

I would contact Huub at HuMa in the Netherlands via e-mail asking exactly this Q

Use:  https://huub74.securearea.eu/contact-huma-air.com?sid=v982h40c5q6se599phiu15ssi7&Lng=en

[dcorvino]

Hi
You might want to contact Niick at Air superiority
He sells Huma products and might me able to help you out
Hope this helps

http://www.air-superiorityproducts.com/


Dave

[D-RIG]

+ 1 give Nick a call I'm sure he can help you out .

[Motorhead]

Nick has no manufacturing capability and would .... direct Q to his supplier as suggested you contact direct.

[Bwalton]

Nick has no manufacturing capability and would .... direct Q to his supplier as suggested you contact direct.

Nick in fact is able to do longer or shorter plenum contacting Huma would be a waste of time. He has done a .30cal reg stemming from a .25cal reg. He is busy at the time, but give him a call any way he might have that part laying around.

[Rallyshark]

Thanks for the input guys!  I will give all the suggestions a try, when I get a little free time at work.  I was slammed today, and didn't even have time to think about it   It would be so much easier if I just had a lathe....

[nappyman]

Nicks the man, I ordered a reg for .25 rainstorm and wasn't getting the numbers I wanted so he sent me a  plenum that goes on the .30 cal, I'm a happy camper. 20 shots @906fps with room to encrease to 950fps but my shot count would be to low for my liking. But I did notify him ahead of time that the regular plenum for the .25 would most likely not get the numbers I wanted, his reply," try it, if it don't work I will send the bigger plenum designed for the .30"🤗👍🏽

[Rallyshark]

I spoke with Nick at ASP today, and he is going to try and  send me a .25 plenum to play with.  Assuming he has one in stock of course, which he said he may be able to dig one up   He did tell me he could do a custom size, if the .25 plenum doesn't do what I want, so he can do/get custom plenum sizes if needed.  I didn't discuss what those costs would be though.  I'm going to give that .25 plenum a go, before I go that route. 

Hopefully, I'll be able to fill you guys in on the results and size difference between the .22 and .25 plenums with a Huma reg...

[Rallyshark]

Okay guys, I said I would fill you in once I got the .25 plenum in hand, so...


That is the .25 plenum on the left and the .22 on the right(AT-44).  As you can see there is a bit of size increase.  Just swapping to the .25 plenum gained me around 25 fps with all other things the same.  I left my reg setting the same(120bar) for now, since I'm short on time for a few days.  I played with the hammer spring for the fun of it, and I hit 1004 fps two shots in a row with the CPD 14.3s.  I think it will shoot even faster, but I only shot those two in a row to see what it would do with another turn.  I ended up backing my hammer spring down about 3/4 turns below what it was with the .22 plenum to bring the velocity back down to the 940 fps range where I wanted it. 

I was still on the reg after 40 shots and that includes a lot in the 960-985 range and the couple of 1004fps shots.  I think it safe to say the efficiency is there   I know I didn't lose anything on shot count, and I gained on adjustability.  I'm sure it will do at least 50 shots at my preferred fps, and probably a few more.  The report is good and snappy and slightly less than before(which was pretty darned quiet).  I like to run my regulator a bit higher than I need to, so I can keep the hammer spring on the efficient side of the knee and keep the gun as quiet as possible.  I know my gun will do over 30 fpe with the reg at 110 before the plenum change.  I like being able to keep the 18-19grain pellets at 900+fps if I want without having to change reg settings though. 

In conclusion, I say order the .25 regulator for your .22 if you're thinking about regulating your AT-44 or Bullboss.  You can use a lower reg set point, or regulate for higher power.  I really don't see a downside to this folks.  The volume loss is minimal, and the extra plenum more than makes up for it in efficiency in my opinion.  You run the same power levels with a quieter report too.  I see it as win win. That's my 2 cents, and hopefully, it'll help somebody else out.

Note:  My gun is modded, so the results may be a little different on an unmodded gun.

[David Mccann]

how expensive are the plenum from asp ??

[Rallyshark]

how expensive are the plenum from asp ??

Well, it is kinda hard to say.  Nick hooked me up, because he wanted to know what the results would be from a straight swap with standard Huma parts I think.  I let him know the results before I even posted here.  I wouldn't expect that it would be very expensive at all, since it is just a piece of aluminum with an o-ring, and the majority of the cost for a regulator is in the reg itself.  The best way to ask him would be to call him.  His number is on the ASP site I think.  Baxter(bwalton) deals with him quite a bit too, and he may also have a .25plenum he could swap out?  Of course, you can always get them straight from Huma too as previously mentioned.  It is a standard .25 plenum for the AT-44. 

As Baxter mentioned earlier, Nick at ASP is pretty busy right now, but I know he'll help you out if he can.  Calling him is the way to go, instead of email though. 

[David Mccann]

thanks,  i was just curious. dont really need one just now.  thank you... cheers

[Cableaddict]

Hey, folks.

I have a .25 cal  Flashpup with a standard HUMA regulator installed.   I'm quite curious about this upgrade.

-  But can someone explain how the longer tube, being open on the inside end, creates a larger plenum?  I just don't get it.
If anything, you'd think it would DECREASE plenum volume, since it's taking up space inside the pressure chamber.

Thx.

[Rallyshark]

Hey, folks.

I have a .25 cal  Flashpup with a standard HUMA regulator installed.   I'm quite curious about this upgrade.

-  But can someone explain how the longer tube, being open on the inside end, creates a larger plenum?  I just don't get it.
If anything, you'd think it would DECREASE plenum volume, since it's taking up space inside the pressure chamber.

Thx.

The plenum is the area behind the regulator, or the piece that fits into the regulator. It sounds like you're thinking the plenum is the space in the cylinder not taken up by the regulator? The plenum is the section where the air is regulated. A larger plenum will decrease the space/volume available in the the air cylinder itself. I hope that helps.

[Cableaddict]

Hey, folks.

I have a .25 cal  Flashpup with a standard HUMA regulator installed.   I'm quite curious about this upgrade.

-  But can someone explain how the longer tube, being open on the inside end, creates a larger plenum?  I just don't get it.
If anything, you'd think it would DECREASE plenum volume, since it's taking up space inside the pressure chamber.

Thx.

The plenum is the area behind the regulator, or the piece that fits into the regulator. It sounds like you're thinking the plenum is the space in the cylinder not taken up by the regulator? The plenum is the section where the air is regulated. A larger plenum will decrease the space/volume available in the the air cylinder itself. I hope that helps.

Ah, I get it now, thanks.

I am not the one who actually installed my regulator, and going by the old HUMA instruction manual pictures, I though it went inside the breech area. (Those instructions are horrible.)   

So that's quite a conundrum for me:  I can get even more power, but then lose even more total shot count, which is really marginal on my Flashpup.
Very frustrating.

Well at least now I understand.

[Rallyshark]

That is the conundrum that many of us air gun enthusiasts have faced at some point   Here's the low down on your Flashpup in regards to regulators.  If you're tuning for low to medium power, the regulator usually wins.  If you want high power, you'll likely get more shots without a regulator(regardless of plenum size).  The gun is capable of a pretty decent shot string without a regulator to be honest.  A big misconception is that you have to have a reg to get a good shot string, and that simply isn't true in many cases. 

If you can keep your extreme spread at 4% or less, then you're good to go.  You'll never notice any difference in POI in most cases.  The only time it becomes really important is for stuff well past 50 yards.  I shoot my hot rodded Synthetic Flashpup without a regulator, and a majority of my shooting with that gun is past 100 yards.  Now, if I wanted it tuned for 30 fpe, then I'd have a reg in it.  I could get more shots at that power level with a regulator.  I have it tuned for 55 fpe, and I could never touch the shot count I get unregulated at that power level vs having a regulator in it. 

[Cableaddict]

Very interesting thoughts, RS,  and thanks.

FWIW, I'm going for the absolute maximum power I can.  It's not some macho thing, and it's not for long-range shooting, either.
I also have little interest in anything more than 50-60 yards away. (Though of course if a fat little cottontail showed up at 100 yards, I'd give it a go.)

My goal is small game hunting, and to always have as humane a kill as possible. 
I'd love to think I can always manage a head or heart shot, but that's simply not the case. So I'm shooting .25 cal hollowpoint slugs.
Slugs of course for their wind resistance.

More power also means a bit less bullet drop, so it's easier to calculate holdover. every little bit matters.
But of course, so does consistency, and there's the rub.
I never did try this gun without the regulator, as it was already installed when I bought it. (used.) It would be interesting to try that.  But this gun has also been drilled out, and typically that means a pretty steep velocity drop off when there's no regulator, based on the articles I've read. 

So...   well my current thinking is to just get a buddy bottle, plus this larger HUMA plenum tube, if I can get one.  It's a minot inconvenience, but not horrible.  I can probably attach it to the forward picatinny rail for transport & storage,  then a belt clip or whatever for hunting.

[Rallyshark]

Very interesting thoughts, RS,  and thanks.

FWIW, I'm going for the absolute maximum power I can.  It's not some macho thing, and it's not for long-range shooting, either.
I also have little interest in anything more than 50-60 yards away. (Though of course if a fat little cottontail showed up at 100 yards, I'd give it a go.)

My goal is small game hunting, and to always have as humane a kill as possible. 
I'd love to think I can always manage a head or heart shot, but that's simply not the case. So I'm shooting .25 cal hollowpoint slugs.
Slugs of course for their wind resistance.

More power also means a bit less bullet drop, so it's easier to calculate holdover. every little bit matters.
But of course, so does consistency, and there's the rub.
I never did try this gun without the regulator, as it was already installed when I bought it. (used.) It would be interesting to try that.  But this gun has also been drilled out, and typically that means a pretty steep velocity drop off when there's no regulator, based on the articles I've read. 

So...   well my current thinking is to just get a buddy bottle, plus this larger HUMA plenum tube, if I can get one.  It's a minot inconvenience, but not horrible.  I can probably attach it to the forward picatinny rail for transport & storage,  then a belt clip or whatever for hunting.

Don't pay any attention to the fact that the gun has been "drilled out".  I'd bet money it is capable of a decent shot string without the reg at higher power.  My .22 SFP is as opened up as far as you can get a Flash, and is capable of over 80 fpe.  Yet, I shoot it unregulated at 55 fpe for 24 shots with an ES close to 3%.  Yes, I have a larger cylinder/longer barrel.  I was able to get 24 shots at 41 fpe with the factory cylinder and barrel, fwiw.  That was with the gun opened up, of course.  All you'd need to do is re-install the large o-ring that goes on the threaded part of the valve, and remove the regulator to see what it will do without it. 

What power level is it currently tuned to, and how many shots are you getting?  Also, what pressure is the reg set for?  I can give you a pretty good guess of what it would do without the reg.

[Cableaddict]

What power level is it currently tuned to, and how many shots are you getting?  Also, what pressure is the reg set for?  I can give you a pretty good guess of what it would do without the reg.

I can't believe you got 80 fpe with a .22 !  You must have that gun tweaked to the last micrometer.  What is that in grains and FPS?


As for my gun,  I don't quite remember the exact numbers, as I set it up in last Summer, and since have dropped/ broken my cheapo chrony.
But the HUMA is set for "180" bar  (just past the 175 mark)    IIRC, I was only getting around 16-18 shots before seeing a slight drop, using 36gr slugs.   I remember it was JUST under two mags. 

Of course, I didn't know much back then, and I may not have set my hammer spring optimally.  I just can't remember.  I always meant to do further tuning when I had time, but then broke the chrony.  If I get the larger plenum, then I'll probably get one of those clip-on radar units, (FX?) so I can re-check & re-tune.