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PostPosted: Thu Dec 12, 2013 8:29 pm 
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TriggerHappy416 wrote:
there may be another purpose to the cone shaped valve and pump cup design. I believe that the main purpose of the cone design was to achieve a pump cup with a skirt shape. Similar to diabolo airgun pellets, the skirt of the rubber pump cup flares out against the tube when compressed during the pump stroke, ensuring an excellent seal against the tube wall. Even as the outer edge of the rubber wears out, the flaring action of the pumping process will ensure a tight seal (as long as the rubber maintains its elasticity)


Keep in mind that any manufacturer of small products that have a 1-year warranty is going to want to be sure the product stays intact for the full warranty period- as you noted, the flaring of the stock piston cup will allow for this as it would be extremely unlikely to harden significantly in the first year of use, whereas an o-ring setup would be more susceptible to rips/tears depending on how well the gain is maintained (i.e. on 90% of the big box-store buyers, not likely too well).


TriggerHappy416 wrote:
This video confirms that there are indeed 2 versions of the front valve cone (I had the extended cone). The flatter one appears to be American, so the pointier version could be an additional method to detune Canadian pumpers.


No- there are only 2 versions of the aluminum valve- based on age- ALL newer valves have the flatter tip, ALL older valves have the more pronounced point. The flatter point version was started up about a year or so ago, and the pointy version discontinued (same on the 760/M4 valves), This had nothing to do with detuning, more likely there was no reason for the point to exist and it saved 1% in aluminum costs getting rid of it (which could add up over the course of many thousands of guns- most sporting goods manufacturers are run by accountants hired by investment-fund owners these days).

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PostPosted: Thu Dec 12, 2013 9:18 pm 
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Thanks for the clarification Eric. I wonder if anyone actually tested the old valve cone vs new valve cone on the same gun.

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PostPosted: Thu Jan 02, 2014 4:59 am 
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Got my chrony working again with the replacement parts from England. Thanks Combro!

I didn't measure the velocities before I plugged the bleedhole and sanded the cone down.

Now it shoots at 498fps @ 10 pumps and 408fps @ 5 pumps(14.3gr .22cal Crosman HP). Are these typical velocities for a stock 2289 with the bleedhole plugged?

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