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

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




“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. 

Ok, design the monster.  Pick the springer of your choice.  Make note of the FPE it produces and the weight of the gun less the sock and hit that number with the appropriate multiplier for a rough idea.  Lets say you have a fairly stout springer putting out 20 ft lbs. and the mechanism weighs 8 pounds.  500/20×8 lbs. = 200 lbs.  Your monster weighs 200 pounds and would have double+++ that for the cocking force.  With the use of titanium you might be able to get it to 130 or so pounds.  And buddy boy think about the reverse recoil and stress on the mechanism, not to mention the shooter.

Air guns are great fun and have their place in the shooting sports.  If you just gotta push it to the max go with a 5500 psi, one shot per fill, nitrogen pcp gun.  Make the bore large enough as in an inch or greater and use sabot rounds.  What you end up doing is making a monster that just might be able to duplicate a $300 dollar center fire for $30,000+.  As for me, I will just grab my trusty old Winchester M70 in 30-06 and know I have a sensible tool for the job at hand.