Is there a low operating pressure PCP out there?

[null]

I seriously detuned a Bandit to shoot 50 shots at ~500 fps.

[splitbeing]

My beeman 1357 is set up for 1600psi down to just over 1000. Shoots ftts around 700 fps for a handful of mags... easily over 50 shots within less than 30 fps ES.  The gun is usually around $250.

[UnderPressure]

I stumbled upon a post by Mike M. from 2011 about an idea he had for a 1500-ish psi PCP rifle based on the XS-60. If something like that (maybe up to 2000 psi) were available in .177 from FDAR or any other source/manufacturer, I would be all over that like stink on poo. My main gripe with my recently sold PCP rifle was shot count. My (regulated) PR900 seemed to have such a puny shot count that it felt like I spent as much or more time pumping it than I did shooting it. I buy guns to shoot them, not fiddle with them. Are there any PCPs out there that fill to 2000 psi or less?

Mike, are you listening?

P. S. I realize that there are limits to the power that such a setup could produce. That's not an issue for me. I would be completely satisfied with 10-15 fpe in .177 and tickled pink with 20.

If you lower fill pressure you will spend even more time pumping for a given size resevoir and shot power level. That is the opposite of what you want to be doing.

[Back_Roads]

 Then there are these oldies but goodies.

[AlanMcD]

If you lower fill pressure you will spend even more time pumping for a given size reservoir and shot power level. That is the opposite of what you want to be doing.

Could you explain what you mean by this?  It does not make any sense to me for the following reasons:
 - Lower power generally leads to higher efficiency - so if tuned well, the gun should use a lot less air per shot (more efficient and less air per shot).
 - If the gun is regulated, a lower fill pressure just changes the amount of shots, not the efficiency.  We'd pump more often but with shorter duration.

I can only see this ro be true if one simply fills an unregulated gun to a lower pressure without retuning that gun to work properly at that level, and then still trying to shoot the same number of shots as before.  That would kill efficiency, leading to using more air per shot (in addition to dramatically increasing the ES of the shot string).

I also don't see what reservoir size has to do with this, unless it changes in some way between the two states.

[Spacebus]

If you lower fill pressure you will spend even more time pumping for a given size reservoir and shot power level. That is the opposite of what you want to be doing.

Could you explain what you mean by this?  It does not make any sense to me for the following reasons:
 - Lower power generally leads to higher efficiency - so if tuned well, the gun should use a lot less air per shot (more efficient and less air per shot).
 - If the gun is regulated, a lower fill pressure just changes the amount of shots, not the efficiency.  We'd pump more often but with shorter duration.

I can only see this ro be true if one simply fills an unregulated gun to a lower pressure without retuning that gun to work properly at that level, and then still trying to shoot the same number of shots as before.  That would kill efficiency, leading to using more air per shot (in addition to dramatically increasing the ES of the shot string).

I also don't see what reservoir size has to do with this, unless it changes in some way between the two states.

Assuming two airguns have an equal efficiency, but one has a small reservoir and the other twice the size, you will still be doing more pumping overall with the smaller reservoir. You have to pump more often, which means you have to prime the pump/hose more often. This is less significant when talking about lower pressure reservoirs compared to something like a 3k fill. Your pump sessions will be longer with the larger reservoir, but less frequent. I don't have experience pumping up a 2k or less gun, but I have a Bandit and Stormrider (allegedly twice the volume of the bandit) which are basically the same guns with different length reservoirs. I've hand pumped both when setup for similar levels of efficiency in differing tunes, and it's almost always more enjoyable to shoot the larger reservoir gun with fewer pump sessions. The Bandit is horrible to hand pump when tuned for six shots on max power, but not a big deal when filling from a bottle. When tuned for max efficiency/highest shot count the Bandit is no problem at all to hand pump for plinking since it can get 18 consistent shots with an Altaros reg set to 100b and a Chaser spring.

I think my Stormrider got some 30-ish shots when tuned down to 100b and a Chaser hammer spring, but I haven't checked this in a long time and never recorded it. I'm going back to that tune soon though, so I can report back if you want to know. With the reg at 100b, you could theoretically just pump the tube up to 2k and still get a decent number of shots. You could probably talk to Lane Regulators and get them to make you a regulator set for 850-900 PSI and with a Chaser/Trailscout hammer spring you should be able to fill a Stormrider up to 2k and still get a respectable number of shots. The lighter hammer spring makes the gun much more enjoyable to cock and shoot as well.

I also realized after typing that you are in fact not the OP. Sorry for the rambling!

[AlanMcD]

Those are all good points DJ, and I agree with them.  But I don't think they speak directly to what UnderPressure was saying so we will see if he adds something to explain it.  I'm not saying he is wrong, just that I don't understand his point . . .

The one thing I will add to your explanation is that back when I was handpumping, I used to set up my guns and tunes for a specific power level and shot count all around one pumping session of ~50 strokes or so after charging the line.  I was simply not a fan of taking a cool down break and then resuming pumping - I wanted to get back to shooting, or simply put the gun away ready to shoot later.  So I had a high power set up that got fewer shots and a low power set up that got a lot more shots, and I would occasionally flip the guns around in purpose (that is how I stumbled on the Air Ranger set up I mentioned in an earlier post in this thread).

The interesting thing is that the different reservoir sizes really did not matter with this approach (500cc for the Air Ranger and 215 for a Marauder), as I was working around one pumping session - it was all constrained by shots I could get out of the 50 strokes of the pump . . . and yes, for general shooting I vastly preferred shooting the gun that got many more shots off a fill, just as you describe.  And of course, that was always the lower powered gun . . .

[Mr.P]

Regarding more pumping for low psi shooting… if this is true could it be because it takes a larger volume of low pressure air to achieve a particular power than it does with higher pressure air?  Little burst of high pressure air versus a larger burst of low pressure air.

I have no idea if this is consistent with reality.

[Doug Wall]

Then there are these oldies but goodies.

I'll second that!! My QB79, with an 1100psi regulated tank, give me lots of shots at close to 20 FPE. You would normally fill to 3000 psi, but you would still do very well pumping to 2500 or 2000 psi.
I also have a Maximus that has a 2000 psi fill.

[avator]

Betty Lou's Maximus has evolved into a repeater with a Boyd's thumbhole laminate stock and a Fortitude shroud and baffles. It still fills to 2k but it's an awesome gun to shoot.

[Firewalker]

I have 2 Chasers, a .177 and a .22, all the additions are swappable.

The .22 has a carbon fiber tank and a cheap-o regulator on it attached to a dropblock.

Open up the regulator and play with the Bellville washers on the 1800psi version until I got 750 fps at 1200psi on the regulator for a shot count of over 100 from 4k to 3k in the bottle.

Guess only that I could get darn near a full tin of CPHPs through her starting at a full 4.5k in the tank.

[UnderPressure]

If you lower fill pressure you will spend even more time pumping for a given size reservoir and shot power level. That is the opposite of what you want to be doing.

Could you explain what you mean by this?  It does not make any sense to me for the following reasons:
 - Lower power generally leads to higher efficiency - so if tuned well, the gun should use a lot less air per shot (more efficient and less air per shot).
 - If the gun is regulated, a lower fill pressure just changes the amount of shots, not the efficiency.  We'd pump more often but with shorter duration.

I can only see this ro be true if one simply fills an unregulated gun to a lower pressure without retuning that gun to work properly at that level, and then still trying to shoot the same number of shots as before.  That would kill efficiency, leading to using more air per shot (in addition to dramatically increasing the ES of the shot string).

I also don't see what reservoir size has to do with this, unless it changes in some way between the two states.

For any given reservoir size (e.g. 210cc) and regulator pressure (he did mention his gun was regulated in the OP) he will need more pumps per shot with a lower fill pressure vs. a higher fill pressure. This because the low fill pressure forces him to connect and disconnect the hand pump more often. The more often the hand pump is connected and disconnected the greater amount of pumping that needs to go into bringing the fill line back up to pressure. The lower the regulator setting the less pumping needed to bring the fill line back up to pressure.

[AlanMcD]

OK - thanks, that makes sense.  But only if one attempts to keep shot energy basically the same.  If the FPE is tuned down along with the reduction in fill pressure, then that relationship would change.

As far as the gun being regulated, he said that was one he sold - he is looking for something different that fits his needs, and it might be possible to tune another gun to meet those needs.

In the end, air usage (and thus the amount of pumping) is pretty much a function of the FPE per shot and the number of shots with the efficiency of the gun/tune . . .

[EdinGa]

The amount of pumping isn't as significant in some cases. My wife can easily pump my guns to 2000 psi but she struggles as the pressure gets higher.

[UnderPressure]

The amount of pumping isn't as significant in some cases. My wife can easily pump my guns to 2000 psi but she struggles as the pressure gets higher.

3 stage pump or 4 stage pump?

4 stage is easier to pump than 3 stage.

[Hoosier Daddy]

Air used per shot.
Amount of pumps to replace the air used per shot.
The PSI the gun designed for to achieve "Full fill PSI" should be irrelevant... no?
If I have a 2000 psi gun that uses say 100 psi per shot and a 3000 psi gun that uses the same.
 If all the variables (cylinder size) is the same, wouldn't it take the same amount of strokes to recover, but be harder to pump on the 3000psi gun?

The Disco / Maximus platform was a 2000 psi gun. Easy to hand pump.. even shoots well on CO2 pressures.
Relatively easy to hand pump to max fill.

[EdinGa]

The amount of pumping isn't as significant in some cases. My wife can easily pump my guns to 2000 psi but she struggles as the pressure gets higher.

3 stage pump or 4 stage pump?

4 stage is easier to pump than 3 stage.

4 stage.

[EdinGa]

A caliber bump might help too. My .25 bottle Bandit makes 14 fpe on an 800 psi regulator.

[Spacebus]

Air used per shot.
Amount of pumps to replace the air used per shot.
The PSI the gun designed for to achieve "Full fill PSI" should be irrelevant... no?
If I have a 2000 psi gun that uses say 100 psi per shot and a 3000 psi gun that uses the same.
 If all the variables (cylinder size) is the same, wouldn't it take the same amount of strokes to recover, but be harder to pump on the 3000psi gun?

The Disco / Maximus platform was a 2000 psi gun. Easy to hand pump.. even shoots well on CO2 pressures.
Relatively easy to hand pump to max fill.

The pump effort does increase with higher fill pressures, which is important to note. There's also variances in pump design, as has been mentioned.

[HOSPassassin]

Wow. I guess there is great interest out there in easy-to-fill, high shot count, just-powerful-enough rifles. Who knew? Thanks for all the suggestions.

The QB79 looks like a definite possibility. If it could be tuned upward a little that would be peachy.

I feel kind of silly for asking now that I have already sold the gun, but is the reg on the PR900 adjustable? I maybe could have salvaged my relationship with it if I had known how to adjust it down. Krale advertised it as making 16 fpe in .22 but mine shot at about 21-22 fpe for about 20 shots before it would begin to drop off quickly. A PR900 regulated to shoot at 12 fpe should get almost twice as many shots, right?

I find it curious after reading all of this discussion that installing a Canadian-spec transfer port in the PR900 did not make more of a difference than it did. It dropped the muzzle energy down to ~7.5 fpe, which is about a 65% decrease from the original TP, but the shot count only went up from 20 to 40. Shouldn't it have gone up to 60 since I was getting only one-third as much muzzle energy per shot?