Hey guys I just completed a series of tests in my basement using audacity on my 2289 that has a macroline transfer port and stronger hammer spring. Does a velocity of 478 FPS at 8 pumps sound right?
This was taken at a constant distance of 11.3 feet from muzzle to a sheet of metal (old computer case SIDE). Attached is an image of how I calculated the velocity, did I do it right??? Also there is an image of the pellet after making a health dent in the pretty darn thick steel sheet.
Webstein.........I think that you've got to move your starting point to the left.........where the wave form actually starts. Note the teeny little squiggle right at the start. I've been getting this and I suspect that it is the hammer hitting the valve pin just before the higher peak that would indicate the release of gas at the muzzle (the 'bang', if you like).
I'm going to go out on a limb here and suggest that the mid spike (where you started) is an echo.......... and that you were correct for the pellet strike (very loud hitting metal).
the pellet also doesn't appear deformed enough to be that near 500fps.
I was thinking that maybe the uniform smaller wave form before the point I chose for the start is the hammer strike and pellet traveling through the barrel and then the slightly higher but still small peak is the muzzle burst (start point).
Any other ideas? I will calculate the velocity using the start of the waveform. Also I just realized that I made a big boo boo in the distance measurements because I was shooting slightly downwards so that would increase the distance the pellet is travelling since my trajectory is the hypotenuse!!
About the echo thing, the room I shoot in has walls of 1 inch thick plywood with a walnut veneer (or something :/) and it has very very little to no echo.
Can anyone with a chronograph and some spare time help us people without a chrony get the right calculations using audacity?
EDIT:
okay, actual distance is 11.65 feet.
Time from start of wave to hit of 0.0365 seconds (rennugliat's suggestion) gives me only 300 FPS? I hope its not that low :/
Remember that this is a pump pneumatic and not a springer so there is a bigger burst at the muzzle that HAS to be higher then the rest of the firing sequence.
Some more pellet dmg pictures. Keep in mind that the steel dented inwards a substantial amount which means that it is absorbing much of the pellet energy and it is NOT anchored down (can bounce back against the wall a bit and is not attached to the computer case anymore. IE: not like shooting into a piece of steel bar stock in a vice.
okay, I knew you guys wouldn't believe my last post (I wasnt so sure myself) so I went and shot, at 8 pumps, into a SOLID piece of steel on the cement basement floor of my house. The results follow.... could a 300fps 22 do this? I'm not being sarcastic, could it?
Copperhead lead is pretty hard stuff, no?
LARRYS WHERE ART THOU!!!!
Last edited by webstien on Sun Feb 12, 2006 9:14 pm, edited 1 time in total.
Shooting into a solid steel plate, I think that that kind of damage may be possible at 300fps. Since the steel plate is essentially absorbing zero of the shock, all of the energy is being forced into the soft lead pellet.
That being said, I doubt that a 2289, even in stock form, would only be shooting at 300fps.
As for LarryS, I think took his ball and ran home.
can anyone with an approx. 475-485 fps .22 cal pumper shoot a copperhead wadcutter into a piece of steel at one inch or so away (wear goggles just in case) and tell me if it looks like my picture??????
Pellets were fired point blank from a 2289 (more or less) at a chunk of steel laying on concrete. Number of pumps below each pellet, chronoed velocity is the 3 digit number below each pellet.
Your pellet looks about like my #7 pellet or somewhere around 400fps.
Fiat Lux
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now im even more confused then before. Using a time of 0.0284 seconds for the pellet to travel 11.65 feet at ~405FPS but im not sure where that 0.0284 second interval goes in the audacity recorded waveform.
I think this 2289 is a bit anemic due to a chip missing out of the piston seal and its plastic breech because my 2289 with steel breech and everything else stock is doing the damage from pellet number 11 at 8 pumps.
Luckily I have a 2100 steel piston assembly coming from crosman and from what I hear it comes with a spare seal.
Check out Audacity's noise reduction feature as well. It makes it soooooooooooooooooooooooooooooooooooooooooooooooooooo much easier to see what's happenning.
