ALIHISGREAT wrote:HYBRID! you have to make a handheld, supersonic pellet rifle think of the accuracy AND power.
There are few supersonic pellet rifles that are particularly accurate. Pellets don't like being near transonic (basically between 1000 and 1500 fps for a pellet). That's why it's good to get a rifle back at about 800-900 fps if you want to hit anything with it accurately.
I also doubt you've grasped the pressures that would need to be available to go supersonic from a 14" 0.177" barrel.
You're probably talking a 20x hybrid at minimum
to go supersonic (1200 fps) with even a lightweight pellet like a 7.9 grain Crosman Premier. And to be frank, probably at least 30x if you want a sensible chamber size.
Short small bore barrels need lots of pressure to get energy. My 0.177" TX200 carbine (which has a pretty short barrel for an air rifle) puts out about 4% the energy HEAL can, but needs pressures about six times higher to do so - and that's only trying to get 800 fps, not 1200 or so.
Personally, and with no offence intended, I can't see a huge heap of potential in a 0.177" barrel unless you've got the means to develop pressures that are worthwhile.
That's why if I were doing it, I'd not be looking at any of the conventional methods. Nah, I'd be doing an electrothermal cannon for this, because those can generate some bitching pressures.
Larda's ETG remains the most effective cannon for it's size on the forum, yielding pressures a good 50% higher than even his hybrid could create at a full mix.
Done right, you could nudge pellets the other side of the transonic region and start to get some accuracy back.