Solar wrote:The FBI has been going around to Hobby stores trying to collect info on customers who have purchased drones and/or have such skills as to create what you are speaking of. They obviously are surprised it hasn't happened yet either.

For all we know it already happened and it was kept quiet.

But what about the Caselman? Is anyone building one on here? Has anyone? I read a couple of years ago that Mr. Caselman had partnered with someone to start producing them.

They have definitely been built, but I don't know of anyone on this forum who went ahead and followed the plans in detail.

I'm pretty sure that with a bit of imagination and a modest budget, a private individual could land a payload on a GPS coordinate from many kilometres away, something which is pretty scary and I am surprised there hasn't been a major incident of this type reported.

Yup amateur drone community has been very lucky that none of it happened so far. The worst part is that you don't even need energetic materials for it.

POLAND_SPUD wrote:

I'm pretty sure that with a bit of imagination and a modest budget, a private individual could land a payload on a GPS coordinate from many kilometres away, something which is pretty scary and I am surprised there hasn't been a major incident of this type reported.

Yup amateur drone community has been very lucky that none of it happened so far. The worst part is that you don't even need energetic materials for it.

ikr, a bird sized glider with a thermal camera launched from a weather ballon 80k feet with a preprogramed flight over area 51 would be awesome. Also make the video feed be downlinked live so even if they shoot it down, nothing is lost

Ok this is cool, but I can't see the pictures because I'm stuck on an iPad, anyone mind posting a pic?

I wonder how a Caselman-style blowback would work with a balanced hammer valve, with a much weaker spring needed to knock the valve open you could presumably achieve a repeating cycle with much less pressure than the 3000 psi recommended for the original.

Above concept drawn to scale with a Crosman 2240 type grip and trigger group, and a 13ci HPA bottle (click to embiggen)

jackssmirkingrevenge wrote:I wonder how a Caselman-style blowback would work with a balanced hammer valve, with a much weaker spring needed to knock the valve open you could presumably achieve a repeating cycle with much less pressure than the 3000 psi recommended for the original.

Does the blocking element of the bb`s have a spring? or is it with an air chamber?

hectmarr wrote:Does the blocking element of the bb`s have a spring? or is it with an air chamber?

Yes there's a spring, you can see it in the last drawing I posted.

Edit: build started, turns out my Crosman grip dimensions were a bit off on the original drawing so here it is redone to more accurate scale:

I'm very much looking forward to this!

Select fire, full, or semi? I've been working on disconnector designs and come up with a few things but open bolt full auto is the ultimate in simplicity.

Anatine Duo wrote:Select fire, full, or semi? I've been working on disconnector designs and come up with a few things but open bolt full auto is the ultimate in simplicity.

The Crosman trigger group as-is only allows for open bolt full auto, however an easy way to have semi-automatic is to use a paintball grip, most basic designs having a resetting sear:



The next project after this would indeed be a semi-automatic in a larger caliber.

Here's what I have so far in the meantime:

Some progress this morning, plenum chamber components anchored in place and breech attachment made. Now to make the poppet and see if it holds air and what sort of hammer is going to be needed.

Wow! Impeccable work Why is the bronze pipe used to shoot normally used? Or is it exclusively built for that weapon?

Jack, this scheme will not be more effective? The piston in the bypass is smaller than the volume in the drummer.

keks2033 wrote:Jack, this scheme will not be more effective? The piston in the bypass is smaller than the volume in the drummer.

Interesting! My plan is to test it with the barrel bolt only first to see if I can get it to work like that, if not a secondary pistol will be added.

Why is the bronze pipe used to shoot normally used? Or is it exclusively built for that weapon?

Do you mean the barrel? It's a KS part, they have a huge choice: http://www.ksmetals.com/26.html

Poppet valve done in the meantime and after tweaking the valve seat everything sealed well at 850 psi:



If you look closely at the valve stem there is a groove that connects to a hole in the center of the body, in order to avoid the valve being slammed open by the chamber pressure as soon as it cracks and dumping the chamber.

That was an excuse to have a bit of fun using a brass bar dropped by gravity as a hammer and the barrel tube held in the breech attachment:



The #4 birdshot easily went through the bottom of a soup tin at close range which is about the performance I wanted for a plinker

Wasted quite a lot of time yesterday trying to sort out an inconsistent seal with the poppet valve which mostly boiled down to insufficient valve spring preload, but that seems to be largely sorted now.

I made a quick PVC hammer with a brass insert and it works really well, even the weakest spring I could find it seems to be letting out too much air:



I managed to chrony some lead shot, velocities ranged between 630 and 570 feet per second, given the variation in size this wide range is not surprising.

From what I've seen so far, I'm very optimistic that there will be enough power to cycle the action without a secondary piston. Now to make a proper hammer and breech.