left & right Posted January 3, 2011 Report Share Posted January 3, 2011 HI folks I zeroed my scope on my new TDR for the first time the other day at 170 bar, it was bang on got a good group all within a 2p size circle. Later that day i filled it up to a full 200 bar and had a shot and it was shooting about 6'' low and i couldn't adjust the scope any higher. I kept shooting and eventually it came accurate again round about 170 bar, any ideas why it does this is it my scope or grain of pellet or is it the rifle? Quote Link to comment Share on other sites More sharing options...
The Duncan Posted January 3, 2011 Report Share Posted January 3, 2011 You have an unregulated pcp, which means it has a power curve. If memory serves, the max recommended fill pressure is 190 for your rifle. By over-filling it, more pressure is put on the valve which means it is harder for it to open to release air for the shot. Thus the valve opens less and lets less air out - hence lower power. AA pcp owners can tell you the number of shots in the sweet spot (portion of charge where the point of impact varies the least). I'd recommend double checking the manufacturers fill pressure recommendation. ATB Duncan Quote Link to comment Share on other sites More sharing options...
bruno22rf Posted January 3, 2011 Report Share Posted January 3, 2011 Join the Air Arms owners forum and ask what the "sweet spot" is for your rifle-this is the best pressure to charge to to give you the most consistency over the most shots-its a good forum and loads of good guys on there. Quote Link to comment Share on other sites More sharing options...
FalconFN Posted January 3, 2011 Report Share Posted January 3, 2011 (edited) As above. My rifle has a max pressure of 200 bar but I never fill it more than 175 bar as the perfect sweet spot is around 165 to 125. You can get it regulated (by Tench?) which will give consitant power from 200 to 100 bar but it will probably cost you another £150. edit: 6" low at 200 seems a bit much though. Edited January 3, 2011 by FalconFN Quote Link to comment Share on other sites More sharing options...
left & right Posted January 3, 2011 Author Report Share Posted January 3, 2011 You have an unregulated pcp, which means it has a power curve. If memory serves, the max recommended fill pressure is 190 for your rifle. By over-filling it, more pressure is put on the valve which means it is harder for it to open to release air for the shot. Thus the valve opens less and lets less air out - hence lower power. AA pcp owners can tell you the number of shots in the sweet spot (portion of charge where the point of impact varies the least). I'd recommend double checking the manufacturers fill pressure recommendation. ATB Duncan Cheers mate big help Quote Link to comment Share on other sites More sharing options...
gixxerboy Posted January 3, 2011 Report Share Posted January 3, 2011 As above mate... you shouldn't be filling to 200 unless its a regg'd gun. You'll probably find that anywhere between 170 and 180 bar is where your sweet-spot starts but a chrono run will confirm this. ATB Quote Link to comment Share on other sites More sharing options...
left & right Posted January 3, 2011 Author Report Share Posted January 3, 2011 As above. My rifle has a max pressure of 200 bar but I never fill it more than 175 bar as the perfect sweet spot is around 165 to 125. You can get it regulated (by Tench?) which will give consitant power from 200 to 100 bar but it will probably cost you another £150. edit: 6" low at 200 seems a bit much though. Thanks mate great help Quote Link to comment Share on other sites More sharing options...
hoTshoT-16 Posted January 4, 2011 Report Share Posted January 4, 2011 my mate has the s400 and does the same its sweet spot is around 170-180 bar Quote Link to comment Share on other sites More sharing options...
HoTsHoT-10 Posted January 4, 2011 Report Share Posted January 4, 2011 I fill mine to 190bar i can't hit any thing so fill it to around 175bar and fill up again at about 100bar . (classic version) Quote Link to comment Share on other sites More sharing options...
left & right Posted January 5, 2011 Author Report Share Posted January 5, 2011 my mate has the s400 and does the same its sweet spot is around 170-180 bar Cheers Quote Link to comment Share on other sites More sharing options...
left & right Posted January 5, 2011 Author Report Share Posted January 5, 2011 As above mate... you shouldn't be filling to 200 unless its a regg'd gun. You'll probably find that anywhere between 170 and 180 bar is where your sweet-spot starts but a chrono run will confirm this. ATB Will do mate cheers Quote Link to comment Share on other sites More sharing options...
left & right Posted January 5, 2011 Author Report Share Posted January 5, 2011 I fill mine to 190bar i can't hit any thing so fill it to around 175bar and fill up again at about 100bar . (classic version) I'l try it mate nice one Quote Link to comment Share on other sites More sharing options...
HoTsHoT-10 Posted January 5, 2011 Report Share Posted January 5, 2011 Just found this mate and might help so thought i would post it. http://airarmsownersclub.com/viewtopic.php?f=13&t=30278 Quote Link to comment Share on other sites More sharing options...
hoTshoT-16 Posted January 5, 2011 Report Share Posted January 5, 2011 Just found this mate and might help so thought i would post it. http://airarmsownersclub.com/viewtopic.php?f=13&t=30278 interesting regulators are not cheap tho Quote Link to comment Share on other sites More sharing options...
left & right Posted January 5, 2011 Author Report Share Posted January 5, 2011 Just found this mate and might help so thought i would post it. http://airarmsownersclub.com/viewtopic.php?f=13&t=30278 Thats helped a lot mate thanks Quote Link to comment Share on other sites More sharing options...
shooter22 Posted January 9, 2011 Report Share Posted January 9, 2011 i have had a few of these and as said they have a sweet spot fill to 170 take a shot count to 110 then it will be bang on Quote Link to comment Share on other sites More sharing options...
andrewjames Posted January 14, 2011 Report Share Posted January 14, 2011 only way to find out your sweet spot is to invest in a cronograph, (mine is the combro mk4) ive done my s410k .177 and now im getting really nice groups all the time (because i know what pressure to fill the cylinder) once you get your crono, fill the rifle up to 200 bar and fire pellets through the crono until your cylinder reaches 50-100 bar... with the saved results you can plot the data onto a graph to view an actual power curve. whats also nice about this information is you can also see what fps spread you getting within your power curve and what power in ft lbs your getting. when i cronoed my rifle i was getting 11.00 - 11.30 ftlb within my sweet spot which equates to around 11 fps spread which isnt to bad. and my sweet spot was from 150 bar to 100 bar... i never shoot outside of the sweet spot as accuracy suffers and for me is considered a waste of pellets. id also recommend using mid weight pellets if you plan on tuning your rifle, you dont want a heavy pellet to push you over the 12ftlb limit. always stay within 10.5 - 11.5 ftlb hope that helps andy Quote Link to comment Share on other sites More sharing options...
left & right Posted January 14, 2011 Author Report Share Posted January 14, 2011 only way to find out your sweet spot is to invest in a cronograph, (mine is the combro mk4) ive done my s410k .177 and now im getting really nice groups all the time (because i know what pressure to fill the cylinder) once you get your crono, fill the rifle up to 200 bar and fire pellets through the crono until your cylinder reaches 50-100 bar... with the saved results you can plot the data onto a graph to view an actual power curve. whats also nice about this information is you can also see what fps spread you getting within your power curve and what power in ft lbs your getting. when i cronoed my rifle i was getting 11.00 - 11.30 ftlb within my sweet spot which equates to around 11 fps spread which isnt to bad. and my sweet spot was from 150 bar to 100 bar... i never shoot outside of the sweet spot as accuracy suffers and for me is considered a waste of pellets. id also recommend using mid weight pellets if you plan on tuning your rifle, you dont want a heavy pellet to push you over the 12ftlb limit. always stay within 10.5 - 11.5 ftlb hope that helps andy Cheers mate big help Quote Link to comment Share on other sites More sharing options...
The Duncan Posted January 14, 2011 Report Share Posted January 14, 2011 (edited) IF you need to tune your pcp rifle, you might as well sell and get an HW100 S or T, as they have a secondary chamber to reg the rifle. Means fill to 200, get 110 shots in .177 and no sweet spot - all pellets hit the same spot and no thought or consideration required Worth the money. Every penny :yp: Edited January 14, 2011 by The Duncan Quote Link to comment Share on other sites More sharing options...
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