# Reply To: A theoretical exploration of physical possibilities, AKA Let's Make A Monster

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“sharroff”We have a 500 fpe .45 PCP (Texan) that puts out twice the energy of a 45 ACP handgun shooting match ammo. It’s so long it doesn’t fit into some gun cabinets and loud enough it sounds like a real rifle going off (which it is). Why take that and force a spring into the equation?

From the original post:

Namely, is it theoretically possible to create a viable large-game hunting rifle (meaning .45 or .50 cal, 800-1000 fps) using a spring or gas-ram powerplant? Logistical considerations aside (cost, weight, insane cocking force and murderous recoil), is it possible to produce sufficient muzzle velocity, and how might it be done? If we can come up with a decent answer (and I can come up with the cash), this may turn into a custom-built abomination.

Again, this thread is about making a springer in a similar class that can be shoulder fired.

__ Let’s design this thing!__ Do we want to use a caliber .45 with a 192 grain pellet (1.4 times the weight of a lead round ball which is about proportional to a 11.5 grain .177 or a 22.4 grain .22), or the caliber .50 with a 263 grain pellet?

Next, we need a barrel length. What is the shortest barrel (in terms of caliber) springer that meets the desired 850 ft/s or so with these weight of pellets? We can use this as a baseline. That is, take the barrel length in inches and divide by the caliber. Use that and multiply by either .45 or .50 to determine the length of the barrel for this big springer.

Taking our sample smaller caliber springer, we need to determine the volume of the compression chamber of the big gun (again in terms of barrel volume). We will need to choose a compression chamber diameter as well.

Then, we need to figure out how much air pressure the original spring can generate, and/or its energy (average force time the travel distance **F** x d), and scale this up to our piston diameter. I think that a gas spring of some sort would be easier to build since we could vary the pressure in it to get the force/energy required.

Finally, we need to consider how to put this monster into a shoulder fire-able stock. A trigger release mechanism that does not require a 40 pound trigger pull, yet is safe. And a means to cock the thing fairly easily.

"sharroff"We have a 500 fpe .45 PCP (Texan) that puts out twice the energy of a 45 ACP handgun shooting match ammo. It's so long it doesn't fit into some gun cabinets and loud enough it sounds like a real rifle going off (which it is). Why take that and force a spring into the equation?From the original post:

Namely, is it theoretically possible to create a viable large-game hunting rifle (meaning .45 or .50 cal, 800-1000 fps) using a spring or gas-ram powerplant? Logistical considerations aside (cost, weight, insane cocking force and murderous recoil), is it possible to produce sufficient muzzle velocity, and how might it be done? If we can come up with a decent answer (and I can come up with the cash), this may turn into a custom-built abomination.Again, this thread is about making a springer in a similar class that can be shoulder fired.

__Do we want to use a caliber .45 with a 192 grain pellet (1.4 times the weight of a lead round ball which is about proportional to a 11.5 grain .177 or a 22.4 grain .22), or the caliber .50 with a 263 grain pellet? Next, we need a barrel length. What is the shortest barrel (in terms of caliber) springer that meets the desired 850 ft/s or so with these weight of pellets? We can use this as a baseline. That is, take the barrel length in inches and divide by the caliber. Use that and multiply by either .45 or .50 to determine the length of the barrel for this big springer. Taking our sample smaller caliber springer, we need to determine the volume of the compression chamber of the big gun (again in terms of barrel volume). We will need to choose a compression chamber diameter as well. Then, we need to figure out how much air pressure the original spring can generate, and/or its energy (average force time the travel distance__

**Let's design this thing!****F**x d), and scale this up to our piston diameter. I think that a gas spring of some sort would be easier to build since we could vary the pressure in it to get the force/energy required. Finally, we need to consider how to put this monster into a shoulder fire-able stock. A trigger release mechanism that does not require a 40 pound trigger pull, yet is safe. And a means to cock the thing fairly easily.