Challenger 2009 hits 72.5 ft lbs

[CarsonRatSniper]

The weather had a sunny patch so I made it to the range this afternoon.
Last night I decided to open the throat of the factory Challenger valve. There wasn't enough meat in it due to the depth of the valve retaining screws but the throat is 7/32" and I'm running a 3/16" transfer port, so it works.
Here's what I discovered though:
My 'flow enhanced' Crosman Disco stem had come apart as Bob had warned me about when I said I ground it down. It still shot Kings @ 965 but all of my things I did to move the useable pressure up and increase velocity didn't work - now I knew why.
Luckily I ordered a Delrin stem the day after Bob said that 'just in case' - so the new stem was installed.
I also took off 2-3 threads from the cap for a bit more volume.

Another big one is I has threaded the gauge too far into the Prod port effectively blocking most of the tube flow feeding the valve.

After fixing these things I went to a 2850 psi fill...........the first 25.4 grain JSB came smoking out at 1048 fps! Then 1048 again, 1046, 1052, 1045, 1048, 1038, 1036, 1026 & 1021 ending at 2200 psi.



I filled back to 2800 psi and tried the 48.8 grain semi wadcutter cast bullets - 781, 776, 796, 785, 807, 795, 798, 798, 818 & 807 ending at 2200 psi.







I'm still playing around with things but I'm VERY pleased with a Max of 72.5 ft lbs out of a slightly modified Challenger 2009 powertrain.



I shot a steel 55 gallon drum we use as a burn can from 50 yards and I was able to recover the slug.
It punched through the side, blew through a barrel full of cardboard boxes and plastic and lodged against the other side of the barrel.




It only shot 1.5" @ 50 yards - not spectacular but I'm pretty sure I know why.

I'm moving forward with my swaging die setup. That way I control the length and weight of the slug.
The bases MUST be absolutely uniform or you get the circular pattern (group) I got.
I believe the fact there is no concave hollow pocket to trap the air is a big contributor.

More to follow.................maybe I can get a coon or yote with these bullets.

[kj]

that's sweet. you and that hammer collection. lol.once you work out the bugs it'll be time to start a new project.

peace
kj

[CarsonRatSniper]

Thanks
I'm not sure about any more builds - I love tinkering and the learning process but these get expensive.
I have no regrets as I have a fantastic & powerful one of a kind rifle.

I will post swaged bullet results when I have $400 to invest in the die, cutters and lead wire core.

That way I can punch out slugs anywhere from 20 grains to 70 grains and feed the rifle what it likes to shoot accurately.

The way I cut my breech lead I'm guessing it will prefer a round nose 55 grain that has an air pocket in the base.

We'll see!

[pyroboy33]

Wow that's some impressive power, my hat's off to you my friend  .
                                                Cheers
                                                             Caleb C.

[CarsonRatSniper]

Thanks!
The string average was 70 ft lbs.
What's crazy is the retained energy cast bullets have vs pellets.
50 yards is carrying 60+ ft lbs and 100 yards has 53 ft lbs.

What's that? Did I just hear a yote???

Hmmm............Rocky Raccoon, Steve Skunk, Pauly Possum, Barry Badger - Yep! I've got a long hit list now!

[kj]

Thanks
I'm not sure about any more builds - I love tinkering and the learning process but these get expensive.
I have no regrets as I have a fantastic & powerful one of a kind rifle.

I will post swaged bullet results when I have $400 to invest in the die, cutters and lead wire core.

That way I can punch out slugs anywhere from 20 grains to 70 grains and feed the rifle what it likes to shoot accurately.

The way I cut my breech lead I'm guessing it will prefer a round nose 55 grain that has an air pocket in the base.

We'll see!


lol..tell me about expense. i just gave in and bought a handful of barrels , breeches and valves, and added several tools to my shop.  perhaps i need profesional help. be looking forward to your further testing.

peace
kj

[Topend Yobbo]

Ummm , to much speed = bad accuracy?
Have I not read that a billion times?
Good one for smashing the velocity numbers on an air gun , sounds cool.

[Habanero69er]

Ummm , to much speed = bad accuracy?
Have I not read that a billion times?
Good one for smashing the velocity numbers on an air gun , sounds cool.

With a diablo pellet yes, because of the hollow or concave skirt which causes turbulence. A cast bullet with a flat or boat-tail is a another animal.

[CarsonRatSniper]

^+1^ At 965 fps it shot a 1/2" group with Kings at 75 yards (basically). Total group size was 1.6" but 7 out of 10 shots went into a 1/2" group.

If you look at the picture of my group there's 2 bullets in the same hole with one touching that hole - those 3 went in the same place.
It may be due to a bit of throat jump due to how I cut my lead - I wanted it to be easy to load.

At 1050 fps the JSB's are all over the map to the tune of 2"+ groups at 50 yards.

Today I'm going to the range to back off the RVA and play with pellet velocity so the pellets are accurate again.

The only thing I've noticed with a 1:14 twist 25 Cal barrel is the POI shifts are substantial driving the same pellet at different velocities and different weights at the same velocities.

The pellets hit 4" right of the bullet impacts at 50 yards. Vertical zero is unaffected.