What'cha doing air gun related today?

[SpindleB]

That’s a casual 85FPE out of a gun that im pretty sure costs less than $1000 right? That’s pretty outstanding.

Not a lot of shots at those increased pressures. But I have 3 9L and several other tanks i can use as a tether

 

[Cantona256]

Not a lot of shots at those increased pressures. But I have 3 9L and several other tanks i can use as a tether

That’s the eternal tradeoff sadly… that does give you choices though. I bet you could tune it for 65-70FPE and get a pretty good shot count… or just hot rod it into a 5-8 shot railgun gun lol. I feel like the world deserves to see what a 46g slug from that gun will do to a coyote.


Also you got a lot of tanks bro… you ever get tired of lugging those things around feel free to send one over

 

[SpindleB]

That’s the eternal tradeoff sadly… that does give you choices though. I bet you could tune it for 65-70FPE and get a pretty good shot count… or just hot rod it into a 5-8 shot railgun gun lol. I feel like the world deserves to see what a 46g slug from that gun will do to a coyote.


Also you got a lot of tanks bro… you ever get tired of lugging those things around feel free to send one over

I have smaller ones to backpack. There are/were adjustable fill valves on AliExpress. I have 2, one is set for 2,000 psi the other is set for 200bar. Both are on 3L bottles.

The big tanks are for working on my guns at night so I dont run my compressor. I am an engineer so I always have some idea rolling around that causes be to drain the tank(s).

 

[Cantona256]

I have smaller ones to backpack. There are/were adjustable fill valves on AliExpress. I have 2, one is set for 2,000 psi the other is set for 200bar. Both are on 3L bottles.

The big tanks are for working on my guns at night so I dont run my compressor. I am an engineer so I always have some idea rolling around that causes be to drain the tank(s).

That’s awesome dude. All jokes aside I work as a machinist/tool maker. We do Swiss turning and all extremely high precision stuff. So if you ever need/want to run some parts.

 

[SpindleB]

That’s awesome dude. All jokes aside I work as a machinist/tool maker. We do Swiss turning and all extremely high precision stuff. So if you ever need/want to run some parts.

LOL, where were you 3 months ago.
Had some male to male m18-1.5 adapters made that had 23mm rings to butt orings against.

They were built because I've been playing with plenums. Oring would blow around a COTS m18 adapter. So I needed the 23mm with relief.

Just working out the optimal size based upon barrel volume. Turns out to be 3x or 4x barrel volume. BUT only really applies to the AirForce type platform. Falls apart when transfer ports, hammer springs, poppet valves and dwell time get involved. I have no way to calculate the volume of air past the poppet per trigger cycle and I don’t have the tools to measure it.

 

[Cantona256]

LOL, where were you 3 months ago.
Had some male to male m18-1.5 adapters made that had 23mm rings to butt orings against.

They were built because I've been playing with plenums. Oring would blow around a COTS m18 adapter. So I needed the 23mm with relief.

Just working out the optimal size based upon barrel volume. Turns out to be 3x or 4x barrel volume. BUT only really applies to the AirForce type platform. Falls apart when transfer ports, hammer springs, poppet valves and dwell time get involved. I have no way to calculate the volume of air past the poppet per trigger cycle and I don’t have the tools to measure it.

That’s really interesting stuff. I’m also really interested in plenums. In the Bob Sterne articles he says 1/2-1cc of plenum volume per FPE you wanna generate puts you on the right side of the power curve. Transfer port @75% of caliber… so 4.7mm for .25cal… I’m very interested in testing some of that out at some point.

 

[Rusty]

Hateful Mcnasty have a good day And Be Well Brother, Rusty, a brother from another mother and another forum.

 

[JimT66]

Hateful Mcnasty have a good day And Be Well Brother, Rusty, a brother from another mother and another forum.

I don't think Hateful is on here anymore Rusty.

 

[SpindleB]

That’s really interesting stuff. I’m also really interested in plenums. In the Bob Sterne articles he says 1/2-1cc of plenum volume per FPE you wanna generate puts you on the right side of the power curve. Transfer port @75% of caliber… so 4.7mm for .25cal… I’m very interested in testing some of that out at some point.

This all started because I put a Dream Valve on my .22 Talon with a 19 inch barrel.
Had the regulator set at 200 bar and got 1100FPS and 68FPE

So I decided to figure out the optimal plenum volume.
What I did was calculate the barrel volume and then tried 25CC, 50CC, 125CC and 250CC plenums.
Huben Power Dream Valve Universal: 25CC Plenum
Huben Power Cricket Max-ATH: 50CC Plenum
Shan Bao 20CM 300psi Tube and regulator 1/2 of a Huben: 125CC Plenum
Shan Bao 40CM 300psi Tube and regulator 1/2 of a Huben: 250CC Plenum

This was with AirForce .25 Condor and Talon with 24 inch barrels.
(.125*.125)*3.14*24= 19.31CC
The objective was to find at what point adding more plenum volume reached diminishing returns.
3x or 4x barrel volume seems to be optimal
Sufficient plenum and air path (which the AirForce platform provides) you can accelerate the pellet the length of the barrel.
The 50CC was good little short of 3x
The 125CC pretty much maxed the FPE gains at 6x
The 250CC was virtually identical to the 125CC

Bob Sterne was working with a conventional Poppet style rifle.
Way too many variables in the air path to do anything other than find what a specific rifle can add via plenum
Hammer spring
Hammer weight
Poppet spring
Transfer Port
Poppet Dwell
Air pressure
Plenum port
Right angle air flow changes

I'm sure there are probably others but change any one of those and you change the volume of air through the Poppet. So optimizing the plenum is custom for each poppet rifle.

The Condor firing H&N 30gr Barracuda was getting 880FPS ate 1750psi with the 125CC plenum
Same gun and the 25CC plenum required ~2000psi.
Cranking the regulator to 200bar with the 125CC and the pellet went supersonic.
You can really lower the regulator pressure with a well optimized plenum.
Or you can get some bit time FPE

Unfortunately the Shan Bao tubes are on AliExpress are either out of stock (40CM), with the wrong style regulator (40CM) of big jump in price (20CM). The other issue there is connecting up those tubes to a standard air rifle.
To do that gets a tad heavy and unwieldy. Need a U adapter.

Niksan Ozark .25, Shan Bao 40CM tube, Huben Regulator, Huben U adapter and a 1.6L bottle.
Note the droop on the tube

 

[Cantona256]

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So it’s been another week of playing with my gun since I’m just hellbent on turning this thing inside out apparently haha… after hitting the reg with the reg butter a couple weeks ago I opened the transfer port up to 4.4mm yesterday. I’m looking to set up a really solid “medium” tune. My goal is 65fpe and 30 shots a fill… but while waiting for my 32gr slugs to come in I went out and played around the 28gr I have. Going 985/990fps(edit*) lol these things are cooking…. The mic picked up the thwack pretty good for 95yards.

 

[PapaT]

I printed destroy the dot, five and dime, and hard seltzer challenge targets in preparation for shooting at my dad's in a week. Also looked at pic rail tube bands and test moderator from RCO, that I received yesterday. My trigger finger has withdrawal shakes though... too long with no pew.

 

[Cantona256]

I printed destroy the dot, five and dime, and hard seltzer challenge targets in preparation for shooting at my dad's in a week. Also looked at pic rail tube bands and test moderator from RCO, that I received yesterday. My trigger finger has withdrawal shakes though... too long with no pew.

Test moderator??!? Can we get a sneak peak? What’s going on at your dad’s a shooting competition? If so I understand your preparation.. some of those old timers can really shoot.

 

[JimT66]

Being me, I am always on the hunt for airgun "stuff". Came across this this morning at the same flea market I found my .177 crosman/Remington a few weeks ago. Thought it was just an empty dust catcher.

 

[PapaT]

Test moderator??!? Can we get a sneak peak? What’s going on at your dad’s a shooting competition? If so I understand your preparation.. some of those old timers can really shoot.

You can have a sneak peak:

6 baffle instead of 7, tighter hole through the unit. (Orange one is test unit).

At my dad's, there will obviously have to be some competition. He, my brother, and I all have matching Crosman M1 Auto, limited red ryder, and Pinty 22 pcps. Plus, there will be a large collection of airguns in general to play with.

 

[PapaT]

Took P-Rifle out for a Mad Minute Challenge. My first success.

 

[JimT66]

Took P-Rifle out for a Mad Minute Challenge. My first success.
View attachment 14037View attachment 14038

PapaT, do you just leave the fill probe inserted in the rifle at all times? I sure been thinking about doing exactly that, instead of trying to keep them straight.

 

[PapaT]

PapaT, do you just leave the fill probe inserted in the rifle at all times? I sure been thinking about doing exactly that, instead of trying to keep them straight.

Yes, then I don't have to chase it.

 

[JimT66]

Yes, then I don't have to chase it.

I wasn't sure if they would stay in place. That's what I will do.

 

[PapaT]

I wasn't sure if they would stay in place. That's what I will do.

Pinty is my only one with adapter, and it stays for sure. Idk about other guns.

 

[JimT66]

Pinty is my only one with adapter, and it stays for sure. Idk about other guns.

Only one I had with fill probe was my Notos, I been leaving the probe in my compressor fitting so I wouldn't misplace it. Always taking it out, then replacing after airing up whatever I had been shooting. Then came the P-Pup and it's probe. Now the Akela, and the ELF-W. If they will all stay tight in place. That's what I will do. It's kinda APITA putting them back in the factory box's, like I do spare mags, between fill ups.