SSP vs PCP

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bereznov
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SSP vs PCP

Post by bereznov »

I have been unsuccessfully searching for information regarding single stroke pneumatic ( ie FWB 103 ) vs a PCP pistols regarding how consistent the velocities of the pellets are from shot one to shot 60. Any help out there?
Guest

Post by Guest »

The diference in velocity variations between PCP and SSP could be a problem if you shoot scores in the 595 range, otherwise (just like the endless discussions on air pistol pellets testing) the pistol will out shoot you with ease and you need not worry about it.

But, from an "enjoyment of use" point of veiw, the PCP pistols are much nicer to shoot.
James
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Post by James »

SSP's are probably a bit more consistant then pcps.
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RobStubbs
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Post by RobStubbs »

James wrote:SSP's are probably a bit more consistant then pcps.
Why do you say that ? , I would have thought the opposite.

Rob.
Guest

Post by Guest »

i too feel that ssp would be better unless the mechanism for pcp can compensate for a cylinder that keeps dropping pressure as you shoot.

without actually knowing how it works i figure that ssp charge with a fixed volume of air each time which is released and so there isnt any variation in the pressure and power provided to the pellet. unless of course the air in the surrounding suddenly changes density and composition.

for pcp im sure anyone who has used one will know that once the pressure drops, your grouping starts dropping and "recoil" starts to die off. i was shocked when i shot a p34 thinking it is was rock solid only to be told its because the cylinder is severly underpressured.

so i guess unless they manage to make pcp shoot only at specific pressure, ssp would be better. but the increased number of mechanical and moving parts might make pcp more reliable in the long run.
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Richard H
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Post by Richard H »

Anonymous wrote:i too feel that ssp would be better unless the mechanism for pcp can compensate for a cylinder that keeps dropping pressure as you shoot.

without actually knowing how it works i figure that ssp charge with a fixed volume of air each time which is released and so there isnt any variation in the pressure and power provided to the pellet. unless of course the air in the surrounding suddenly changes density and composition.

for pcp im sure anyone who has used one will know that once the pressure drops, your grouping starts dropping and "recoil" starts to die off. i was shocked when i shot a p34 thinking it is was rock solid only to be told its because the cylinder is severly underpressured.

so i guess unless they manage to make pcp shoot only at specific pressure, ssp would be better. but the increased number of mechanical and moving parts might make pcp more reliable in the long run.
The device your talking about is called a regulator which all pcp pistols have. All the PCP pitols have a range in what they shoot (all of which are way more than enough to shoot a match plus a lot more). The regulator takes from the high side and drops a consistant presure level to the low side. This occurs very accuraetly and consistently as long as the minimum pressure is available to operate the regulator (around 65-to 70 psi). The Morini locks up and won't let you shoot the others you just have to know when it is.
Guest

Post by Guest »

is this regulator built into the cylinder?
i wonder how the design a regulator for a specific pressure reducing it when its too high while not allowing shots when its low.
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Fred Mannis
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Post by Fred Mannis »

Anonymous wrote:The diference in velocity variations between PCP and SSP could be a problem if you shoot scores in the 595 range, otherwise (just like the endless discussions on air pistol pellets testing) the pistol will out shoot you with ease and you need not worry about it.

But, from an "enjoyment of use" point of veiw, the PCP pistols are much nicer to shoot.
Perhaps. I have shot matches with both types and have found that going through the process of reloading and cocking allows my mind to settle and prepare for the next shot. The differences between my IZH and my Steyr lie not with PCP/SSP, but with fit and balance.
Steve Swartz

Post by Steve Swartz »

- PCPs are regulated (to a very high degree of consistency)
- SSPs are relatively "leaky" and "unforgiving" in the sense that the consistency of pressure delivery is very dependent on user technique

Also, to Fred's comment, the additional complication of cranking the handle may work for him but represents a hassle/extra work for others.

If SSPs were more consistent, why on earth would they be as unpopular as they obviously are, esp amng world class shooters?

(also consider maintenance, complication, reliability, etc. etc.)

Steve Swartz

(p.s. a regulator works to limit the pressure delivered to the charging chamber- as long as the cylinder pressure is higher than charging chamber pressure, each charge will be 100% consistent. When the cylinder pressure gets below what's required [the only circumstance threatening consistency], many match grade pistols have a variety of lockout mechanisms preventing firing or notifying shooter.)
David Levene
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Post by David Levene »

Anonymous wrote:is this regulator built into the cylinder?
No, it's part of the gun.

Anonymous wrote:i wonder how the design a regulator for a specific pressure reducing it when its too high while not allowing shots when its low.
With due respect, that's why they are making guns and you, presumably, aren't.
Fred

Post by Fred »

I most certainly do not claim to be an expert on this, but I have chronographed a number of airguns through the years, so I can speak from experience (rather than theory).

Of all the types of airguns I have chronographed - spring-piston (SP), single stroke pneumatic (SSP), CO2, and compressed air (CA) - the SSP pistols have clearly shown the most consistent velocities. This has been true of even very old designs, such as the Walther LP3 (when in good working condition) and the AirMatch 600. The SSP pistols usually stay within +/- 5fps, while SPs will vary by as much as 30-40fps, CO2 by 20-30fps and CA by 20-30fps. These are the results of quick tests for function, not some kind of truly scientific testing regimen. However these figures are about what I have come to expect after doing this a number of times.

I would also like to note that Tom Gaylord did an extensive test on a couple of multi-stroke pneumatics, a design type that would seem, at first glance, to provide the least consistent velocities. For each fixed number of strokes - e.g. 4 or 6 - he got amazingly consistent chronograph figures, almost as good as an SSP would give. He also found that these guns were quite insensitive to variations in charging techniques, giving the same readings no matter how they were charged (within reason).

However, none of this matters! Firearm projectile velocities vary far more than do airgun pellet velocities, and firearms can be extremely accurate in practise, over much longer distances than 10M. All of the airgun types are capable of shooting possibles, and the top-level shooters' shifts from one type to another over the years have been due to many factors other than consistency of velocity.

The above has been my experience, YVMV (your velocities may vary).

FredB
James
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Post by James »

Thank you Fred, its good to have some objective data.

SSP's and Multipumps are the most consistant.

Pcps and especially regulated pcps are not the most consistant.

My regulated pistol has a variation of 10-20 fps. A SSP pistol will vary under 5 fps like Fred states. With many only doing 1-2 fps.

Contrary to common belief Steve :) , the method of pumping does not change the consistancy. I've seen tests done where the gun was pumped fast, slow, hard etc. and there was very little variation in fps (+- 5 fps)

Why arn't SSP's more common if they are most consistant then? Becasue 20 fps wont change POI at 10M
Steve Swartz

Post by Steve Swartz »

The "technique" issue is not speed of pumping but the time delay between completing the stroke and firing the shot. This is a factor when the compression piston seals are worn- the problem is not with brand new/impeccably maintained SSPs, but with the SSPs everybody actually shoots in competition (not at the factory laboratory).

Yes I agree that in either case the velocity difference is most probably negligable. And lower pressure does not necessarily mean lower shots OBTW- shots could go higher with lower pressures (within reasonable limits).

And certainly I would be very interested in seeing the studies referred to. My own very limited* measurements contradicted what is being said here. I was specifically studying velocity variation among 6 guns (2 SSPs and 4 PCPs) and found the SSPs to have measurable (statistically, not practically significant) wider variance in shot-shot velocity.

Not having the data at hand- I remember velocity variations weren't that large- but that there was a difference when simulating "reasonable match conditions" (that included aborts and delays; see below).

I didn't have a "theory" to go by; I just wanted to know for those 6 guns what the variations would look like.

Would be interested in details of other studies y'all have done- including info on any "laboratory" (probably manufacturer) studies. Contact me offline at leslieswartz@verizon.net if you get the chance. I can dig up the details/data of my tests if you're interested.

Steve Swartz



*limited to only two examples of "good condition but well used" SSPs [FWB 65 & Crosman 747] vs. four "varying condition" PCPs [an ancient Hammerli, a borrowed Steyr, and two Morinis, one 4 yrs and many shots old and one brand new]. Measured velocities with Alpha Chrony @ 10 ft from muzzle. 40 shots; measured actual deviation from average velocity. The shot-average differences were used as the data of interest and t-tests were performed on the differences between the 6 guns. All shots fired from fixture (not ransom rest). Fired 5 "calibration" shots before taking data.

Noted during first run that (serendipitously) when delay between stroke and firing exceeded ~30 seconds (the phone rang), "outlier" values occured. Re-ran experiment with delay times (for all guns) between loading/charging and firing varied from 5 seconds to 90 seconds (simulating shot process with an abort situtation).
Steve Swartz

To answer the original question . . .

Post by Steve Swartz »

. . . which, in all the fascinating discussion, I at least have strayed from:

The difference between "earlier shots" (shot 1) and "later shots" (shot 60) is pretty much nonexistant.

What I apparently have been talking about is the consistency between any individual shot(s).

There is no degradation in consistency with either SSP or PCP between a reasonable number of shots (like 100).

Steve


[However, one could argue that in THEORY over a larger number of shots (1000s) the consistency of the SSP will degrade faster than the PCP as the SSP is more susceptible to seal wear being a factor. Perhaps. Again, I only have a sample size of 6 guns to refer to. But "Old Wheezy" did seem to fare a little worse than the newer SSP.]
Fred

Post by Fred »

Steve Swartz wrote:
*limited to only two examples of "good condition but well used" SSPs [FWB 65 & Crosman 747] vs. four "varying condition" PCPs [an ancient Hammerli, a borrowed Steyr, and two Morinis, one 4 yrs and many shots old and one brand new]. Measured velocities with Alpha Chrony @ 10 ft from muzzle. 40 shots; measured actual deviation from average velocity. The shot-average differences were used as the data of interest and t-tests were performed on the differences between the 6 guns. All shots fired from fixture (not ransom rest). Fired 5 "calibration" shots before taking data.
Steve,

For all your methodology - far more sophisticated than my tests - you did not in fact conduct a meaningful test. The FWB 65 is a spring-piston gun, not an SSP. And the Daisy, while a true SSP, is (at +/- $150 new cost) not at all representative of the quality of 10M SSP pistols used by top-level shooters. To compare these two with a Hammerli, a Steyr and 2 Morinis makes apples and oranges seem very much alike. In particular, any conclusions drawn regarding match and long-term performance of SSPs, based only on these two guns, would be completely unwarranted.

FredB
Steve Swartz

Post by Steve Swartz »

Agreed on both points- and yes, the FWB ("old wheezy") was certainly not representative of more modern SSPs.

That's why I gave the details.

And why I ask for details of other studies.

I offered my information up not as an authoritative "answer" to the question (as I noted), but as an example of the level of detail needed to properly interpret any particular "answer."

For example, data taken from factory tests of new manufactured SSPs would have their own set of limitations, as would a convenience test of assorted guns in a garage.

There is no *theoretical* reason why SSPs *couldn't* be as consistent as PCPs, right? Given the same regulator/charging chamber/check valve configuration, the gun doesn't care how the pressure got loaded; by hand, by scuba, or by oxcart for that matter After that, the two systems could be identical.

Anyhow, fascinating stuff as usual but time diverted from training I'm afraid.

Steve Swartz


It's amazing to me how so many rigorous studies get "interpreted all out of shape" when they are characterized by other people who read the study- and may be very well meaning- but by leaving out the specifics tends to over/under sell the results. It's important to get into the specifics. Practically every single "scientific study" reported in the popular press is slanted/misinterpreted or downright willfully misrepresented; e.g. the recent cell phone/male fertility reports.
Guest

Post by Guest »

ok so the types of air pistols catagories according to power plant would be spring-piston, pneumatic and cylinder right? with pneumatic broken down into multi-stroke and single-stroke while cylinder into CO2 and air?

i have seen the testing card for LP10 and also for fwb 100 and 103. out of the factory the 100 and 103 does seem to hold a slightly tighter grouping, didnt measure it but it does look bigger for LP10.
James
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Post by James »

I see, Yeah the state of maintainence the gun is in would cause variances.

How was the consistancy on the 65?

I think we can agree however that when properly functioning, the PCP won't be as consistant. It has to deal with chainging pressures, and the regulator, not to mention the hammer and valve assembly. I think due to the simplicity of the SSP system, it's more consistant. A fixed volume of air, compressed, and all of it released in a dump valve.

It would be interesting to see airpistol shot at 50 meters and what developments that would bring.

Guest, I think the test card has little to do with it becasue the velocity changes have almost no effect on the poi.
Bill177
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Simply stated earlier

Post by Bill177 »

Back in the second post, it was said that "........variations between PCP and SSP could be a problem if you shoot scores in the 595 range, otherwise (just like the endless discussions on air pistol pellets testing) the pistol will out shoot you with ease and you need not worry..........."

I think that statement pretty much summed the subject up for 98% of us.

As for myself, I have an Izzy and a Pardini K2 (Co2) and get interchangeable scores with them. But, I don't shoot at the 595 level either.

An advantage to SSP is the fact that you need only the gun, pellets, and a target. No support equipment.

I have owned several SSP APs - including the Pardini K58 and Izzy. This is my second Izzy. I sold the first when I thought I was moving up in the gun ownership world. The K58 was a mistake and I sold it, replacing it with another Izzy. Did the grip work - yada yada. Most gun for the dollar available in the air pistol world.

Now about PCP ................ I don't - never have, and never will. I shoot Co2 - you know, the old stuff. The pressure is self regulating based on the temperature of the cylinder (and ambient air) - so no regulators are required (simpler??). Some of the purests may argue the point, but unless the air temperature changes from way too hot to way too cold in only a few moments - I don't see where Co2 will ever cause cinsistency problems during a match. A tank of Co2 (20#) typically lasts me more than a year - much more. It costs me $15 to have it filled and there are no hassles about it. Operating pressures are far less - hence, there is less "wear and tear" on the seals. I can easily shoot two matches from a single fill. But, alas, Co2 has fallen out of favor - a victim to the "newest is the best" syndrom.
Ted
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Post by Ted »

Here's my 2 cents worth.
I have coached a high school air pistol team for 11 years and we have 4 izh's( 3 are the IZH 46 M and one a IZH 46)2 fwb 65's and one pardini k58. I have a chronograph and last year chronied them out of curiosity and also to check a one of the fwb 65's that I knew was losing pressure. I use a fwb p34 myself and chronied it too. These were my results from 10 shot groups.
IZH46m- 418 fps average. for one 423 for the other E.S 7 fps for both of them. I chroned two and didn't see a need to do the other one.
IZH 46 390 fps average. E.S 6 fps
FWB 65 (One that sounded low in pressure) 285 fps average. E.S was 20fps. I have since rebuilt it but, haven't chronied it since though.
FWB 65 (the other one) 385 fps average. E.S 6fps. I have rebuilt this too since I felt 385 was tooo low for this gun to do.
Pardini K58 425 fps average E.S 6fps
FWB P34- 436 fps average. E.S 4 fps
I was very surprised to see such a close extreme spread from all the different air pistols. This showed me most air pistols are surprisingly consistent as long as they have decent seals. Now I didn't shoot 60 shots consecutively with them to see what the fwb p34 did after 60 shots but, my match experience shows me it does just fine. Don Nygord had a great article years ago about the switch from ssp to CO2 and CA guns. To give a brief summary he basically said that ssp didn't just become 'doo doo' overnight, it just became easier to shoot the same score with a gas gun versus having to work a ssp everytime. They still all have a very needed place in the shooting world in my opinion.
One more note. Rebuilding a fwb 65 is very interesting!
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