GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: dogmansam on June 20, 2012, 12:54:08 PM
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Since I got my 2400kt 2-3 weeks ago temps have been in the high 80’s up to 100. Gun shoots hard been getting 40 – 45 shots on average 35-37 seem very strong. I let it rest a few minutes between 10 shot strings 10-15 seconds between shots.
As usual with our weather a cold front will come through and drop the temps for a day or so. Approximately 55 degrees this morning. Hustled around to go out and shoot a 40 shot round. All setup and started shooting. On purpose started forcing shots 5-10 secs of rest between trying to be accurate. Shooting 1/2in dots from 17 yards Leapers 4x32 scope. Gun was feeling cold when I loaded CO2. My first 10 shots at the dots I was missing all over the place. This would have been one of those scenarios where you might start fiddling with adjustments. The last 5 days I have been using the same type of target hitting the dots 40%, missing by up to 1/2-3/4 in on some 60% of time, yes I realize I am not that good of a shot; but my groups are mostly in the 1in that is my standard.
As I said I was spraying shots as much as 1&1/2 in right off. After 15 shots I noticed a notable drop in power. So I just kept forcing those shots, and at 25 shots I could tell I was missing all over hit low most of the time, but still hit some dots square on. At 30 shots thing was really laboring, but still getting down range. I forced the next 10 shots up to 40, still had CO2 left, but shots were dropping up to 2in off.
Usually don’t get to test this radical of temp change in a matter of 1 day. I already knew that temp has a big affect on CO2, but to get to experience it like this was really neat. I believe a lot of people repeat the mantra about temp, but I wonder how many have ever actually experienced it.
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Some of the more scientific types on these forums have posted that you can expect about 3fps variation with 1 degree in temp change.
IF that holds true (my experience has been that it is a good guideline) then you went from whatever speeds on the low side of the comparison spectrum at 80 degrees to ~ 75 fps less per shot at 55 degrees (if farmboy math is wright ;) ) and at the high end of 100 degrees, somewhere ~ 130 fps. BIG difference at range, and depending on pellet weight.
I plan to compensate for this 2 ways when my 2400 is done....
1st way...mildot scope is the way to go....dots help my judgement tremendously
2nd way....thinking about opening the valve up some, and replacing the existing striker set up with different spring/weight/ power adjustor. Since the gun does right almost 12ftlbs now, and is perfect at that.....will keep the power adjustor set to 12 ftlbs at ~ 75 degrees. Hopefully thru experimentation and trigger/chrony time I will be able to determine speeds opened up from my base of 75 degrees, so that I can make reference marks on the pistol and adjustor. AS temps fluctuate, say from 75 degrees to 80, I will be able to dial the adjustor back to keep fps within 5-10 fps of my base. Likewise, as temps go down, can stand on the spring a little, and keep POI relatively the same. Now, this will most certainly throw metered shot counts to the wind......but should keep me reliably at 20-25 shots wide open, and who knows how many when choked back.
this all sounds great on paper btw, but have not even opened up the valve yet......so who knows?
God bless,
Farmer
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Some guns are worse or better, I guess. My TF79 takes 2 cartridges, and impresses me with the number of shots before I sense a dropoff... My Steele Storm drove me nuts as it wouldnt STOP shooting (also a 2 cartridge model).
"dang"... I just realized I left my Daisy 300 at my sister's ... phui
Richard
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My Mac 1 LD shoots well from 50-90
The way it is designed I can shoot very close with extreme spreads in temp
BUT when the temps dip too low I still have my regged HPA tank to screw on for 180 shots with 3 FPS spread
Perfect for those autum days where its a bit nippy
I am going to chrony the gun with the CO2 all summer from the 95 were at the past few days and through out all diff temps and keep a good log come fall I will do a full write up with my findings
but keep in mind this gun is designed to run at varying temps so there may not be a ton of spread over all
Now I just installed a fiber optic sight on it last week and was nailing pop cans out to 50 yards off hand today outta 5 shots i hit it 46 times!!!!
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" today outta 5 shots i hit it 46 times!!!!". Man I like that gun!!! Might have get one of them, or did you line up the cans in a single column?
DT
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Lol. My 0 sticks. Haha. I meant 50 shots
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Since I got my 2400kt 2-3 weeks ago temps have been in the high 80’s up to 100. Gun shoots hard been getting 40 – 45 shots on average 35-37 seem very strong. I let it rest a few minutes between 10 shot strings 10-15 seconds between shots.
As usual with our weather a cold front will come through and drop the temps for a day or so. Approximately 55 degrees this morning. Hustled around to go out and shoot a 40 shot round. All setup and started shooting. On purpose started forcing shots 5-10 secs of rest between trying to be accurate.
You mentioned twice that you wait 15 seconds between shots... for accuracy? You will find more consistency in velocity between shots -- translates to accuracy -- if you wait 40 seconds (minimum) between shots. I usually wait a full minute.
Fast shooting cools the reservoir tube excessively, compounding the temperature sensitivity issue, especially at 55º or less. Waiting at least 40 seconds minimizes the cooling effect, so your shot to shot velocities are highest they can be at the temperature, and more consistent as well.
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I agree with the comments about allowing more time between shots.... In addition, you will get fewer shots in cooler weather....
Bob
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You will get fewer shots in general in colder weather, and...
You will get even fewer shots in cold weather if you shoot at 15 sec intervals.
When you notice the reservoir is "Cold" to the touch, it tells you the CO2 within is even colder than the ambient temp. 55º is about the coldest I will shoot CO2. A frosty reservoir tells you the CO2 is much colder than 55º.
Slow down, even moreso in cooler weather.