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Jeremy · Veteran Member

Hi Guys

I have a Crosman Pumpmaster 760 and a Airmaster 77 and today was shooting them both and noticed that the pumpmaster gets more penetration then the airmaster 77?? I pumped them both 10 times each and used the same pellet and fired them both 10 times each and at the same distance and the older pumpmaster kept coming out on top Rolling Eyes

Is this correct? or a problem with the airmaster ?

cheers

Jeremy

Crosman140 · Senior Member

What are you testing your penetration on? A piece of wood has varying densities of grain making the penetration different depending on if you hit hard or soft areas.

It could be a problem with the Remington, difficult to tell.

According to each company, it looks like the 77 is rated at a higher FPS than the 760. This should give it more power. But, that's just what the companies boast. It is always lower in real life.

In that grade of gun, there is probably not as much quality control. When you get into your springers and higher priced pumpers and pcp's, you will most likely get more quality control and more consistency in production.

I have a Daisy Powerline 880 that is rated similarly to your two guns. I've shots rabbits with a head shot and taken them with one shot. The same with squirrels. It just depends on each gun.

Jeremy · Veteran Member

I was shooting at a stack of boxes leaning against a wall

AirGunEric · Site Admin

I believe Jeremy is in Canada (please correct me if I'm wrong)- which likely means one or both of his guns have been "detuned". As mentioned, QC on any gun vs. another can vary- but with this detuning, the actual output of one vs. the other could be drastic. Canadian "detuned" guns are very specific about having a "maximum" output of 495fps- this means one gun could be putting out 490fps, the other 400fps and the claim of a "maximum of 495" is accurate. The only way to verify what each is doing is to use a chronograph, then modifying each/both appropriately. However, this is not an indication of a "defect" necessarily.

Jeremy · Veteran Member

yeah Eric I am in Canada, thanks for sharing that info on detuned guns.

Crosman140 · Senior Member

AirGunEric · Site Admin

Pumpers are usually detuned by having a vent in the valve- i.e. no matter how many times you pump, the valve will bleed off the excess.

Co2 guns will have restrictors to limit Co2 flow at/through the valve.

Springers often have shortened/weakened springs and somethings things like longer pistons (to shorten the cocking stroke and piston movement when fired) and/or vents in the piston/chamber.

The problem with most of these detuning methods is that the manufacturers look at them as little more than an inconvenience. They will do it so they can sell the products in Canada, but if a vent pressure release in Pumper 'A' is half that of the vent in Pumper 'B'- "oh well- it isn't putting out much power in either case anyways..." seems to be the sort of attitude.

Crosman140 · Senior Member

Hmmm...I wonder, then, at what pressure % increase do they set the bleed-off? (rhetorical question)

I ask this 'cause I've pumped my little Daisy 880 10 and then 15 pumps and notice a fairly significant increase in power.