When I was growing up, we had a Benjamin [Franklin] pneumatic pump air rifle. Air pressure stored was dependent upon the number of pump strokes used.

All spring-piston air rifles I have read about - admittedly I do not keep up with spring-piston air rifle technology - use a single stroke to cock its piston. Are there, or have there been, spring-piston air rifles that incorporate the ability to use multiple strokes to increase piston's release pressure. This has always appeared to be a moderate cost method to significantly enhance velocity-power of this technology.

Naphtali-- I hope my answer is not insulting, telling you what you already know. As you stated, the spring air's are cocked--not pumped. The amount of air they generate would be determined by size of piston and distance it travels. Multiple strokes would not increase either.

This operation, where you have a piston traveling forward creates a double whammy recoil akin to popping a whip. This will wreck a scope that is not built to compensate for that action. A scope that would stand up to the recoil of a heavy recoiling magnum centerfire rifle could be wrecked on a spring air rifle that is not designed for it.

I have seen multiple stroke air rifles.

I have no idea who makes them, but have seen them here.

I think they pump a storage cylinder inside.

I have seen others use a pump similar to a bicycle pump too.

quote:

Originally posted by Saeed:
I have seen multiple stroke air rifles.

I have no idea who makes them, but have seen them here.

I think they pump a storage cylinder inside.

I have seen others use a pump similar to a bicycle pump too.

See IF I can make a short version of an answer that clarifies, rather than confuses the issue

Multi Pump
Each stroke of the lever pumps a given amount of air into a cylinder. At some point one can not add "any" air into the storage cylinder (usually about 10 strokes).
When the trigger is pulled a valve system allows the volume of compressed air to be released into the barrel to propel the projectile.

PCP Pre Charged Pneumatic
A high pressure tank, compressor or HIGH pressure hand pump is used to fill a gas storage vessel (2000 - 3600 psi) on the gun that holds enough compressed gas to fire multiple shots. "Firing" is done in various manners depending on the internal design of the gun, but a "small" amount of the total amount of gas stored is used to propel each projectile.

Single Stroke
A piston connected to a spring (gas or metal)that is compressed through mechanical connections and held in the compressed state by the trigger mechanism. Gas is allowed into this cylinder through a one way valve.
When the trigger is pulled, the spring pushes the piston forward compressing the gas in the cylinder and this propels the projectile. It is an "All or Nothing" design so for any practical design, multiple strokes would have no real effect.

Have I adequately confused the issue for all now?
The gun vary in quality and cost from the big box store variety to several thousand dollars.

Like this site, there are many great Airgun sites out there, as well as some very good information on youtube

Guys:

What I was thinking pertains to TCLouis' comment that the piston, one stroke achieving complete compression, being held by trigger mechanism cannot be further compress by additional pumps.

I was asking whether a piston whose compression requires, a single stroke of 150 pounds could have a compressing/cocking that reduced that 150 pounds to five consecutive compressing/cocking strokes of 30 pounds each. This is a completely hypothetical example. Its purpose is to attempt to describe an example of progressively retracting a piston in a spring piston mechanism whose spring is way too strong for a normal person to be able to compress/cock with a single stroke.

Its essential problem pertains to carpetman1's reply. The diesel effect and its huge increase in pressure on the chamber filled with air should cause a recoil effect - probably as a reverse of recoil of cartridge rifle - may?? cause spring-piston rifle to be flung forward so vigorously that the shooter would have the rifle wrenched out of his grasp and propelled toward the target rather than bashing into his shoulder.

That non-air rifle scopes are designed to withstand force being supplied in the opposite direction compared with spring piston air rifles' "recoil" is merely a design detail. And air rifle scopes are designed that way now. However, the "recoil" effect of my example would be way too much for anything now made. I mean, after all, why make scopes and mounts for a problem that doesn't exist.

I think that if one had a mechanism to compress the spring in stages it would be the same effort required, just in smaller increments and with the addition of more parts.