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HPA or LPA rifle

7K views 16 replies 7 participants last post by  guajiromotherfcker 
#1 ·
Hey guys...

Well after looking at the Right Hook rifles for a long time, and drooling the same amount. I was thinking of just using low pressure air, as to not have to worry about a dive shop to fill a tank.

I currently live up in North Dakota, and it gets cold up here! And i do know that CO2 is a pain in the colder months, as well as red gas and the like. I do know that compressed air doesn't fluctuate all that much, compared to the gasses.

I was thinking about using a small paint ball tank, and fill with compressed air, and use this as a propulsion. I would love to have a gas rifle but it just isn't practical here in ND.

What do you guys think about this idea? I have a few plans in my head that i would like to try with this. But I am not to sure if it would work. That and how many psi does one need to get a .3g BB, or higher up to the needed fps?
 
#2 ·
I don't know about the PSI, but I can tell you that you will need a HPA specific tank. You should have no trouble with HPA because its already a gas in the tank, whereas propane and Co2 are liquids that convert into a gas. From what I remember compressed air is not as consistent as Co2 so I don't think it would be a good propulsion system.

On his website he says he can sell the gas system for 200 something. You might want to look into that if you really plan on making your own.

sticks
 
#3 ·
I was kinda thinking about using CO2 but I know from paint ball that it can be really jumpy as well. That and i am not to sure how the bucking would act with liquid CO2 on it.

I do know that my air rifles, the PCP type, are all very consistent. Even in colder weather, there is a little drop but nothing as bad as propane or what not.
 
#4 ·
I'm no expert when it comes the the gas/air differences in FPS, but I know from my ballistics studies and experiments that the fact that air the projectile is traveling through is cold will slow it somewhat. Because the air is cold, the molecules are moving slower which makes it more difficult for the projectile to cut through. That may be why there is the little drop you are noticing woogie. There isn't anything you can do about that but increase the FPS/PSI to compensate.

I found myself curious why Right Hook didn't make a hollow buttstock with a small HPA tank inside it. Then it could feed directly through the bolt into the rifle rather than having to attach through the magazine.

I'm trying to figure out how to use a smaller cylinder and stronger spring to make it a little more realistic and open up space for a casing/BB cartridge and action...I dunno.
 
#5 ·
phridum said:
I found myself curious why Right Hook didn't make a hollow butt stock with a small HPA tank inside it. Then it could feed directly through the bolt into the rifle rather than having to attach through the magazine.

I'm trying to figure out how to use a smaller cylinder and stronger spring to make it a little more realistic and open up space for a casing/BB cartridge and action...I dunno.
This is exactly what I am thinking about. I was then thinking about my paint ball days. And i remembered the RAP4 paint ball. They use a small air tank in the retractable stock, they use it as the main stock tube.

I was looking at hiding the air source inside of the stock. So that it looks totally stock. That and when thinking about the high pressure air, as with the PCP rifles, you need a special air pump to get the required pressure to fill up the tank. And those usually go around $250 for the cheapest.

That and what about those little air source tanks? Are those CO2 or compressed air?

I did know about the air being more dense in the cold and what not. But i always thought that when the outside temp is colder than the air inside the tank. That the air in the tank will cool to the temp outside. And with CO2 and propane, it will stay one temp regardless.

Thanks for the help guys.. any more input would be great. I am just starting to toss around some ideas. As i am looking at getting a small mill and lathe when i get my new place ;)
 
#6 ·
Phridum: I thought about that when I saw the video too. But how would the gas get in the bolt? Maybe a port under the safety area? But if something went wrong it would be a big hassle to fix it.(ie. gas leak). I know most of the paintball remote coils can handle HPA, but does anyone know where to get one of these if we wanted to shorted the coil? Im looking for smaller HPA bottles right now and the smallest is the size of a large Co2 tank.

sticks
 
#7 ·
I have found some small 3.5 ounce air tanks that would work. That and with the remote coil, to get them smaller just take them to a local air shop or someplace, and ask them if they could shorten it for you. I know up here in ND I can take the coil to Praxx air and get it done.

I would love to get something like this working. I do know that there is I believe a King Arms air bolt. And that may work for a bolt, and for only $100 that isn't to bad. But I think that is only for gas though ...
 
#11 ·
Yeah El, I just found a rifle over on uncompanys site. It looks like the old school pump paint ball markers. That was when I started thinking about using a CO2 tank. Would be a lot cheaper and easier to do.

But the one question that I keep on having is, how would the cold CO2 act with the bucking? Are you still going to get a really consistent hop up or no?

I did see on that rifle on un's site, the wa shan S001 I believe, only has a fixed hop up. And that would be no good i would think, as you would have to get a certain type of bb and nothing else.
 
#12 ·
the shilling effect should be no worse that what you get with green gas/propane or 134a/Difloroethane. For Co2 to really chill, you need to decompress a fair amount rather quickly. You see this in paintball because you need more gas to push A paintball than an airsoft BB.

If you shoot a lot (more so on full auto), your regulator may chill a bit, but if you make a shot every now and then, you will have no issues.

the rifle you mentioned is set up to use 12gram Co2 cartridges. these work, but can be very erratic. it is possible to use an adapter for a gas bottle (constant air is what paintballers used to call it), but i have no idea where to look. Push comes to shove, I have a South Bend model 9 lathe in the basement here in Wisconsin. I can make one for you out of brass or aluminum.
 
#13 ·
Sweet!

Thanks for that offer El. I just found out from work that I can use all the machines there if I want. Just as long as I know how to use them


So mills and lathes at my disposal


I have some of my paint ball stuff still, and one of them is a 20 oz tank with a nice regulator. So I may use that and mill and make everything else
 
#14 ·
Chances are, if you're talking about a 3 1/2 or 20 ounce tank then it's designed for CO2. The name refers to the amount of CO2, in weight, the tank can carry. CO2 usually runs about 850 psi at room temperature but it can spike up to 1200 psi, or even higher, in hot temperatures. CO2 tanks do not usually have regulators, instead using a pin valve.

HPA tanks are designated by their capacity for air (in cubic inches) followed by a slash and their maximum PSI fill capacity. For example, a 68 cubic inch tank that can be filled to 3,000 psi is called a 68/3000. Most paintball HPA tanks are 3,000 or 4,500 psi, although a few are 5,000 psi. This doesn't mean the tank lets out the air at that pressure. HPA tanks have regulators that release the air. There are high pressure (usually around 850 psi) and low pressure regulators (350-ish psi) on bottles. Some regulators are adjustable but most are preset.

3,000 psi tanks are usually made of steel while the 4,500 psi ones are fiber-wrapped (and much lighter).

Many paintball players use a second regulator, on their gun, to further reduce the HPA pressure coming into the gun. Many paintball companies manufacture regulators for using with HPA. Again, there are low pressure (500 -) and high pressure (500 +) regulators. There is not a lot of overlap between the two types. All of these on-gun regulators are adjustable. The low pressure ones can go from 1 to around 500 psi; the high pressure ones can usually go from 500 to around 900 psi.

There is a move in paintball toward low-pressure guns. This means the gun operates at a lower internal pressure and uses less air pressure to move the paintball. This reduces wear and tear on gun internals, makes for a quieter gun and is more gentle on brittle or fragile paint. The downside is, to make up for the lower pressure behind each shot, the gun has to use a larger volume of air for each shot.

CO2 can liquefy at around 40 degrees-ish F (I don't know C) while HPA is much more stable.

If you're looking for CO2 or HPA-related devices then you may want to look at:

http://www.palmer-pursuit.com/

If you're interested in small HPA tanks:

http://www.wevopaintball.com/3000psitanks.html

More than anyone probably wanted to know,

Josephus

*DISCLAIMER: I have no financial dealings with either Palmer Pursuit or Wevo.
 
#15 ·
Thanks Joe.

I did paintball for like 12 years.. had a few different types of paintball guns, and i must say that my favorite was the phantom. That is what I would like to make this rifle act like. And I have a bunch of my paintball stuff in storage that I will need to dig out. I think I have a palmers regulator and expansion chamber that I could use.

That is why I feel really fine with working with CO2. I have used it and worked with it for so long while paintballing.

I am starting to find the parts now, and I hope to start the detailed drawings this weekend.
when i get some cutting or something done I will post pics for everyone.
 
#17 ·
I have been using Gas airsoft snipers for about two years, all with external air suply i have try both Co2 and Hpa, it doesnt matter wich type of gas you pick youll need regulator, i personally recomend you SMART PARTS MAX FLO LOW PRESSURE REGULATOR
those are the old big ones that came with the old impulse and shocker markers.....those are cheap, reliable can take mud, sand, and a hell of a beat....and still constant and accurate for sniper sharp shooting......for sniping and low pressure good accuracy and stabilty with Right Hook fabication rifle, Tanaka or Kwj runing on external source i would say you would need some 90 PSI.... while on Co2 to produce the same amount of energy you would need a bit more pressure like 100 + Psi......for example on my upgraded kjw m700 140 Psi would produce the same power/velocity of Co2 at 170+ Psi even though i live in hot wether about 38-40 celcius degree on average day..... i hope that helps
 
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