My disco's a gas hog.

[Ribbonstone]

Didn't run it to a full 4% variation, but that would have come close to 36-38 shots.



Down to 20 foot pounds, which seems to be enough for everything I've been shooting.

[tjcib]

I bought a discovery as my first PCP and after watching the usual online videos etc I was expecting to get at least 20 good shots per fill. I thought something was wrong when I was only getting about 8 shots before my poi dropped about an inch at 20 yards.
 I decided to take it up to Tim at Mac1 and he explained everything to me about different hammer springs etc that crosman has used. Anyway hoping to pick it up with a better shot count and improved accuracy although it has been shooting through the same hole with 15.89 JSB's at my 20 yard range. I'd love 20 shots at double the yardage.

I think you can be confident that it will be great when you get it back from Tim.

[Martis 1]

I have a lot to learn about shot count, etc., but here is the string Norm sent with my gun.  I don't know what pellet he use.
822, 845, 844, 832,837,843, 839,822,828,815,806,798,778.

Low fps:778.  high fps:845.  Ave fps:823.  Extreme spread: 67.  Standard deviation: 19.

I'm willing to be this can be evened out a bit...
Ron.

[Martis 1]

Just got off the phone with Crosman.  A new power adjuster assembly from a Challenger and a hammer spring from a 2260 are on their way.  Total price is under $18.  I sure like Crosman!
Ron.

[Benjamin]

An extended probe will give u extra fps which may slightly increase shotcount. 

Has anyone had experience with GMAC probes...

[tjcib]

An extended probe will give u extra fps which may slightly increase shotcount. 

Has anyone had experience with GMAC probes...

My extended probe didn't really increase fps. But it did make my shot string more consistent. The curve is very consistent with no peaks or valleys.

[Martis 1]

I recieved my 5" TKO yesterday and installed it.  Very pleased with the fit and finish.  Appears to be pretty durable and doesn't interfere with filling the gun at all.  Performs well enough for my needs as well. 

I'm anxious to try out the PA and lighter spring when they arrive.  Not sure how to start out though.  Installation seems simple enough, but do I crank it down till the spring binds up at first, or what?

Ron.

[Gerard]

Sure, you can try max spring compression first and run a string through a chrony, see what kind of curve you get. Probably won't be optimum there though with a stock hammer mass, more likely worse air wasteage than you've seen without the RVA. I expect you'd start to see better curves from start to finish by at least cutting a few turns off the spring then dialing up the spring preload. But you'd need a fair bit of trial and error to determine just what balance is right there with any given hammer weight and other conditions.

[Martis 1]

Had an interesting change.  I installed the 5" TKO, ground down and replaced the fill cap.  Went together really well. 

Today I settled down on the sand bags to shoot some groups.  Before the TKO, the gun grouped the Crosman domes and the 18.3 grain JSB's the best.  The Crosman's grouped generally better than the JSB's but I always seemed to have one flyer per 5 shot group.  As a result, I shot up the 18 grain JSB's in my sampler pack and ordered a full tin.

Today when I benched the gun and shot groups at 25 yards, things have changed a bit.  I pumped the gun to 2,000 psi, then shot the first two groups with the Crosman's.  Groups were bigger than they used to be.  Then I pumped the gun back up, and shot two groups with the 13.something grain JSB domes.  These pellets didn't perform well pre-TKO, but they sure do now! 

Just goes to show that when you change barrel harmonics, other things change as well. 

Next thing I need is an AO scope.  I'm currently using a good quality, Weaver 2.5-7 rimfire scope that's parallaxed at 50 yards.  Even at 4X, I can see some parallax issues at 25 yards.  I think an AO scope will tighten up my close range groups a bit.

Ron.