Courtesy of Kevin (Dealerman) of Impact Airguns .
Velocity vs. Power
OK, enough of manufactures hype on Velocity! Here in the US, we are so obsessed by “how fast is it rated” that many have lost sight of the big picture, or the less experienced marksman is being misled. Velocity by itself means little, even more so if at 1200+ FPS you can’t hit your target with any consistent accuracy. If you are a true marksman, what is more important, accuracy or speed? Now with that said, if you are shooting the fastest airgun out there and you can’t hit the broad side of the barn, what have you achieved?
The fact of the matter is we should focus our efforts on a balance of first accuracy and then maximum velocity. To determine velocity, the preferred method is the use of a chronograph. A chronograph uses two photo eyes set at a specific distance that never changes. When the discharged round passes this optical field, it calculates the time from point “A” to point “B” and thus velocity is determined
Supersonic or Subsonic
Before we move on, let’s talk a bit about supersonic and subsonic issues. At sea level, the sound barrier is at approximately 1116 FPS on a given day. Remember that when a pellet travels faster than the speed of sound, you get a pronounced crack as the barrier is broken. Now when a pellet nears or breaks the sound barrier, it losses stability and thus accuracy is lost.
Most veteran shooters learn that the optimum FPS falls between 700 - 900 which deliver the balance of speed and consistency. Those that shoot PCP or a Magnum Springer will utilize heavier lead pellets to maintain an acceptable velocity and achieve the desired consistent accuracy.
Most, if note all manufactures, use the lightest lead available to perform these velocity tests and thus allow for unrealistic velocity numbers. You will never obtain accuracy of any rifle that touts 1200 FPS using the test ammo. This is why it is important to experiment with various styles & weights of pellets when you acquire a new rifle
Pellet Killing Power (knockdown)
The technical verbiage for this would be Kinetic Energy. A customer once asked “How can the starlings I shoot just fly away and then suddenly drop from the sky”. The problem was that he was shooting right through the target and had very little Kinetic Energy to knock down the target on impact. Knockdown power is crucial when hunting to prevent a varmint from running over to your neighbor’s yard.
The solution, use a heavier lead to offer more impact area and that translates into immediate desired results. A rifle shooting heavier lead at 850 – 950 FPS is most favorable. If you acquire a Magnum (or supermag) you will find that the heaviest pellets consistently perform best as it bring the velocity down to that range of 900 FPS. Same is true for any caliber and any rifle, if your grouping is not what you expect, experiment a bit with a variety of heavier lead.
***The point being : those of you sitting at about 800 fps ...Welcome to the Fold...***
seen this article before and have to agree with it, " speed can kill" any type of speed, power on the other hand can be controled. to have speed and power at the same time is to create an imbalance
my 34 gives me 600 fps, 48 is in 700 and 460 fps is 840 all in CP's .22 cal. and are good up to 30-40 yards, if I need more will buy a rimfire .22
warren
and remember "it's 30% the gun and 70% the shooter"
I am so glad to see other people, especially an airgun dealer, talking about this subject and offering QUALITY and ACCURATE information, including the major variables...
feet per second [fps]
muzzel velocity [mv]
pellet weight
foot pounds of energy [fpe]
I will keep this very short, which is not in keeping with my usual posts...laugh...I have posted this info in the past, but I feel that it is worth saying again:
My "tuned-for-power-not-smoothness" Diana 350 Magnums yields the following results through my F1 chrony:
Pellet = Beeman Kodiak - average pellet weight on digital scale = 21.1+ grains
Pellet balistic coefficent = 0.037
Muzzel velocity (measured in Feet Per Second) = Mid to High 670's
Foot Pounds of Energy at the muzzel using 670fps as a base number = approximately 21.03 fpe (foot pounds of energy)
Velocity of pellet at 55 measured yards = approximately 556.39 fps (feet per second)
Foot Pounds of Energy at 55 measured yards = approximately 14.50 fpe (foot pounds of energy)
At a measured 55+ yards, I am getting "over-penetration" or "pass through" in the thickest area of feral pigeons (enter through chest - exit through back)...and the same, OCCASIONALLY, on desert Jack Rabbits at 40+ yards (via range finder) with a "behind the shoulder" POI (point of impact)
There seems to be a lot of emphasis on FPS on these airgun forums, not to mention FPE. Quite a few armchair comparisons of guns are made using computer software, too. The bottom line is how does YOUR gun do with the pellets you are shooting? If your gun is a magnum and shoots supersonic but has acceptable accuracy for the tasks you give it, then that is ok.
I guess the term 'magnumitis' sort of fits in here. Take a look at the earlier thread on the Diana 27. A good hunting rifle within its intended range and quite a sedate performer. Compare that to a stock magnum springer. "Teeth-rattling"? "Scope killer"? "Screws backing out"? "Pulled my shoulder cocking"? Most appear to take a good bit of work to settle them down. Kind of reminds me of posts about magnum centerfires where the owners can only take a ten or fifteen round bench session, then head for the Anacin bottle.
What is the theoretical upper limit on springers, anyway? That is, would a conventional design eventually tear itself apart given a powerful enough spring?
RF wrote:
<What is the theoretical upper limit on springers, anyway? That is, would a conventional design eventually tear itself apart given a powerful enough spring?>
Rhetorical question? I think a comment on another thread is revalatory in that the poster sez that he can accept 3,000 rounds thru his gun before spring failure. You have GOT to be shi##ing me! That is so remote from 'acceptable' that I can't even visualize it in my worst nightmare. I can only imagine it originating with one who worships at the 'Chrony Alter'. (BTW---this represents no attack on he who made the statement! If that is what HE seeks then more power to him. Pun intended!)
I think that too many lose sight of one seminally salient fact---a gun, whether powered by powder or air, is a tool for killing. So just 'how dead' do you want the quarry?
A heavy .177 pellet at @ 850-900 fps will kill appropriate game as dead as they can get if APPLIED accurately by the marksman. A .22 at 700-750 fps will do the same with a bit more assurance. And both can be made to be very acurate at those velocities all else being equal. If you're killing paper it's much less demanding of terminal energy. Paper is made out of dead trees so little power is needed beyond a clean hole to keep it down until it can be harvested.
No projectile of any velocity up to and past the speed of light will kill what it doesn't hit. 'Close' and 'horseshoes' springs to mind.
Sould you disagree then ask yourself why all forms of competitive shooting are predicated on accuracy and none on velocity. Clear now? Tom @ Buzzard Bluff
PS: BTW RF---just useing your comment as a springboard---no intent to question your credibility at all!!!! And to answer your question: Damned right!
Shooting a spring piston airgun is a sport of ratios. The design itself allows for certain velocity ranges per the individual rifle. Within these ranges the rifle is close to optimum. When that rifle is tuned to match its guts and a preferred pellet, now you've got something. From beyond the basic perameters to a very exact study, which leads away from the presumed answer of velocity the better question of the shot cycle.
We've talked about it before. Tuning for what you hear. How the machine responds to your massaging its internals. This is not about increasing energy levels. Its about the shot cycle.
Its about other things which airgunning isn't, but that's for another post.
