All Springer/NP/PCP Air Gun Discussion General > PCP/CO2/HPA Air Gun Gates "The Darkside"

HiPAC 2260 testing (long post)


Prototype HiPAC 2260 conversion.

Previous post, converting a 2240:

Yellow forum:

GTA forums:,3228.0.html

Here is his web-site.  My 2240 conversion looked exactly like the picture (which is pretty rare advertizing):

Were some bulk fill items made in the past that worked like this one (believe in the above post-string, one member provided some pictures of insert tubes made by DAQ).

Disclaimer: Never met the guy, have no $ interest in his business, and althiuygh I got to test this prototype, have never gotten an product ďfreeĒ.  Just a good common sense design that I wrote about before, so heís taking advantage of the free labor in my tests (and if it crapps out, youíll hear the negative side as well).

HiPAC Converted:

This is a prototype 2260 tube.  Have no idea if it will make it to production or if some features will change (know it will be polished and blued if it makes it into production).

Really a prototype, not polished or blued and with hand  engraved prototype numbers.   Conversion is simple.  Unscrew the factory end cap. Drop in the conversion.  Screw the conversion down by hand.  It will seal against the  factory seal (which is good enough for co2 use) with hand pressure, nop more effort needed than screwing on the factory end cap.  In my case, had to remove the brake and reinstall after inserting the tube to allow it to fit.

Get a sense of the size in these pictures (can click the links to see the 2240 conversion tube):


Having no idea how thick the steel of the conversion tube, have only a guess as to itís internal volume (and Iím not filling the prototype with water to get a direct measurement).  Going to guess the volume of this (based on the 2240ís volume of about 30ccís) to be about 85-90cc.  Just a guess, and perhaps a conservative one.

The standard valve is used.  No need for a filler end cap or a bulk fill vavle, the conversion acts like a long 12gr. cartridge.  One end with a fill nipple, the other end shaped like a 12gr. to seal to the valve, so the Crosman rube is not pressurized.

Realize this is not a ďtankĒ as it is not sealed.  Itís a tube, one end has a hole in it and is shaped like a 12gr..

Can go through the math, but generally co2 bottles use about 42ccís of space to hold one ounce of liquid co2, in the right PROPORTION OF LIQUID TO GAS. Based on that, can estimate a full safe fill (if the tube really is 85ccís) of 2 oz.   Thatís a little more than 56 grams of co2, or about  4.7  12gr. cartridges.

So used as a bulk fill, will hold4.5 X as much co2 as it does when running on one 12gr.  If you get 25 full power shots, then expect about 100-112 if you manage to fully fill the conversion.

(Can search for bulk fill.  To get a full fill, need to create a temperature difference, and itís not always possible to get the rifle 20degrees (or more) cooler than the fill tank.)


Itís a bit cool. So I warmed up the shop to 72 degrees and left the rifle in there for about an hour.

Itís a tuned rifle, but tuned to 12foot pounds using 12gr.   Am not one to tune by smacking the valve harder, tend to smooth the gas flow and use a standard strength spring.

613fps/ 14.3 /  11.93 foot pounds / 26 shots before drop off
(didnít get here by accident, have worked at getting it in the 12 foot pound area as close as possible). 

Co2 Bulk fill/HiPAC conversion:

Left the rifle outside (about 58 degrees) and left the fill tank inside (about 72 degrees). 

That conversion tube is heavy.  With it in place the scoped rifle comes in at 6 pounds 13.8 oz. (rifle by itself is 5 pounds 9.5 ounces).  After bulk filling, the weight was 6 pounds 15.4oz.   So evidently 1.7oz. of co2 made it in (or about  47-48grams). Thatís  about  four 12gr. worth.

621fps / 14.3 / 12.2 foot pounds /  93 shots before showing a let off. Thatís not quite 4X as many shots, but pretty close (and keeping the gun temperature stable is an inexact science in my old shop).

Why not more power from bulk filling?  Did show a tiny gain (8fps), but remember youíre using the same valve and I donít use strong striker springs. Removing the piercing pin would probably show more of a gain with bulk filling, but then you couldnít convert by just unscrewing the HiPAC tube.


Secure the valve with extra retaining screws.   

The air pressure in this conversion (like the co2 pressure) is acting only on the inside of the valve.  A much smaller area to push on that when bulked (bulked, the gas pushes on the outside area of the valve).

Have been some objections to the system being used with HPA, but am not seeing valid reasons not to (within a reasonable pressure).  The issue Crosman tube isnít pressurized.  The valve is retained.  If there is a slow leak where the HPA meets the valve, it will be vented by the loose fit of the valve body to the tube and the front grip housing screw. If worried about a fast leak, then drill the gas tube for a vent hole (it wonít hurt even if you go back to 12gr. use).

If filling  HPA to only co2 type pressures (say 1200psi), should put any more strain on the vale than co2 does (because of the mechanical advantage of threads, cranking on the end cap hard would put much more stress on the valve than the air pressure).

The following I can fully recommend (pressures under 1800psi/120BAR).  Why under 1800PSI?  The valve is set in place, but itís still a co2 valve.

 With co2, the pressure is constant with temperature, so the valve doesnít have to be set up to regulate over a wide pressure range.  Thatís not true with air, and most co2 vales donít make great HPA valves because of it.

Valve has to be smacked hard enough to open it against the pressure of air holding it closed.  So I filled high and shot down, chronographing all the time, to find where the start of the sweet spot was.

(OKÖI like small variation shot counts.  Will count as ďgoodĒ those that are within 3%.  Can use 30fps, but with guns of this speed, 20fps is closer to the 3% rule.)

All tests with 14.3gr. CPís

EXACTLY the same set up as used with co2:  Standard spring with minimal pre-tension:
 80 BAR ( about 1150psi)
15 shots from 623- 641 Ė 624  (lets call that 12.7 foot pounds)

With the standard spring pre-tensioned until the gun just barely cocks:
100 BAR (about 1500PSI)
12 shots 692 Ė 710 Ė 691 (lets call that 15.6 foot pounds)
The normal kit includes  two higher tension springs ( medium high would be the green one, high-high would be the red one).

Swapping out for the green spring, minimal pre-tension:
120 BAR (about 1750PSI)
13 shots  750 Ė 772 Ė 753 (lets call that 18.6 foot pounds)


Really not happy at this pressure, but promised the maker that Iíd try full power.

Green spring and high pre-tension
135 BAR  (about 2000psi)
14 shots   785 Ė 806 Ė 788  (lets call that 20 foot pounds)

RED springÖ cannot pretension as it barely fits in the space and allows cocking.

165BAR (about 2400 psi)

14 shots 803 Ė 831 Ė 799  (lets call that 21.4 foot pounds)

Am sure removing the piercing stem, going to a Delrin valve stem, and some work in porting the valve could add another 2-4 foot pounds to the results.


Have been happy with the .177 2300 conversion, running it at 120 BAR and tuning it down to the 6 Ė 61/2 foot pound area for 15 consistent shots.  With a tube about 3X as large, was hoping to get the same number of shots  at 3X the energy when tuned to run at the same pressure. 

It does that, and Iím pleased with the results.

Once a production version arrives (assume one will be made), would set this rifle  to run at  about 120BAR.  Farting around with spring tensions, striker weight, and the transfer port, expect to eventually find 20-22 shots/ 16-17 foot pounds.

Switching to bulk fill co2 in the summer, would expect a drop to about 13 foot pounds, but something in the 85-100 shots per bulk fill up.


Pressurized to 80BAR, will check for leaks for a few days.  Detected no drop in pressure over a short test, but will check longer-term for any small leak.

Even though more power is not the use I would have for the conversion tube, will replace my stock valve with modded valve. No piercing stem, Delrin stem seal, and a different valve stem return spring system. 

Look forward to any suggestions by Alex (the maker) as to what direction heís care to see this go before this prototype gets shipped back (but I have to say, it will be hard to send it back).

How's that thing working out for bulk CO2?

Only test so far was in comparison to 12gr.  Rifle at all the same settings, just plugged in the conversion unit and filled it co2. Shot about the same speed as it did on 12gr., which you pretty well have to expect as the valve is the same and nothing had changed.

Should respond to tuning just like one running on 12gr. would, the only difference is about 5X as much CO2 on tap.

So if you run out of bulk CO2 you can go straight to PCP or take it out and use a 12g Co2?

Yes.  Can go back to 12gr. by taking the conversion unit out (and using the original end cap). 

Can use it as a low pressure PCP if you've a way of generating 2K pressure.


[0] Message Index

Go to full version
Powered by SMFPacks Media Embedder
Powered by SMFPacks Alerts Pro Mod
Powered by SMFPacks Ads Manager Mod