Guns & Outdoors Forum

CPJ 2.0 wrote: ↑Mon Jan 08, 2024 2:19 pm

Justsomedude wrote: ↑Mon Jan 08, 2024 3:03 am

CPJ 2.0 wrote: ↑Sun Jan 07, 2024 9:57 pm Still using the cross man trigger arrangement ?

No. I'm going to build my own trigger and sear that will fit in the right place for the stocks that im using. It also gives me the ability to make an adjustable or light(er) trigger.

If would be sweet to use a R700 trigger.

R700 trigger sure would add to marketing

Pinned the valve and tested a 65 grain slug at 3000psi. It'll be right where I want it at 4500psi, granted way short of what I initially thought but this also isn't my spiffy valve design, just a poppet valve.

A little progress. I don't know how the hell I managed to do it, but I altered the valve a little, mostly to keep it from slamming internally when it functions but it's only dropping about 250 psi with each shot and I'm still getting nearly the same velocity as I was when it was dumping the whole tank. I'll take that.

Got the hammer and trigger done and taped the assembly into the stock so I could test fire it from the shoulder .

https://youtu.be/qGs-NB-LMYQ?feature=shared

Justsomedude wrote: ↑Thu Feb 08, 2024 12:11 am it's only dropping about 250 psi with each shot and I'm still getting nearly the same velocity as I was when it was dumping the whole tank.

https://youtu.be/qGs-NB-LMYQ?feature=shared

That’s really interesting! What length is the barrel?
What would be even more interesting would be a graph of pressure vs velocity.
My guess is that it would be linear until an inflection point dependent on the volume of the barrel then flatten.
Yeah I know that’s extra work but very useful data.
Your valve design looks like a winner. Nice work.

Japhy wrote: ↑Thu Feb 08, 2024 1:38 am

Justsomedude wrote: ↑Thu Feb 08, 2024 12:11 am it's only dropping about 250 psi with each shot and I'm still getting nearly the same velocity as I was when it was dumping the whole tank.

https://youtu.be/qGs-NB-LMYQ?feature=shared

That’s really interesting! What length is the barrel?
What would be even more interesting would be a graph of pressure vs velocity.
My guess is that it would be linear until an inflection point dependent on the volume of the barrel then flatten.
Yeah I know that’s extra work but very useful data.
Your valve design looks like a winner. Nice work.

I'm not sure on the barrel length. That one is for testing purposes only, which is why its shorter than the air tube. It's actually a 7.62x39 blank that I had so there's some blow by with my .308 slugs. I actually have enough data to graph velocities so I might actually try that.

I don’t think extreme velocity is a firm requirement
I took many whitetail deer in the Midwest with a Ruger SBH
They were all shot through using 240gr jhp at probably about 1200 - 1300 fps. That means some of the energy was not absorbed in the deer and a lighter load would have been just as effective. A 30cal bullet at 1000fps is a viable deer hunt weapon at shorter ranges.