Well he she is my first rapid 7 fac . Fitted with Dr bobs quick fill . Running at 32 ft lb . Shooting with Jsb 18.13g . I shot a whole mag at 160 bar . A d the results were 892.85 to 862.06 . Hopefully that's somewhere where it should ? .
Nice, ;D
nice old gun, 8)
Assuming that its fast-flow......
Would fill to 180 bar then check fps for a mag, log the pressure drop on the main dive cylinder guage and compare with the QF to get a rough the shot count.
Then try 185-190-195 until you find the start of the power curve plateau.
FPS will (should) drop if the pressure is too high and rise again as you get into the sweet zone.
Dont fill past that otherwise you'll be wasting air and pellets, should be able to measure your fills to within a few wasted shots.
Nice would a reg help curve and shot count. Md
Quote from: Squinty on November 13, 2021, 07:27:54 PM
nice old gun, 8)
Assuming that its fast-flow......
Would fill to 180 bar then check fps for a mag, log the pressure drop on the main dive cylinder guage and compare with the QF to get a rough the shot count.
Then try 185-190-195 until you find the start of the power curve plateau.
FPS will (should) drop if the pressure is too high and rise again as you get into the sweet zone.
Dont fill past that otherwise you'll be wasting air and pellets, should be able to measure your fills to within a few wasted shots.
. Thanks for that I will try this tomorrow. Many thanks for your advice
Quote from: Squinty on November 13, 2021, 07:27:54 PM
nice old gun, 8)
Assuming that its fast-flow......
Would fill to 180 bar then check fps for a mag, log the pressure drop on the main dive cylinder guage and compare with the QF to get a rough the shot count.
Then try 185-190-195 until you find the start of the power curve plateau.
FPS will (should) drop if the pressure is too high and rise again as you get into the sweet zone.
Dont fill past that otherwise you'll be wasting air and pellets, should be able to measure your fills to within a few wasted shots.
Looks like a nice Mrk 1 you have M8,
Good old classic is the mrk 1 i love mine and will never part with it no matter what! , My rapid mrk 1 is a death do us part i`m afraid to say lol.
Keep us all posted with how you get on with that Mrk`1 M8,
;)
Hi all . OK filled up to 180 bar put one mag through . 928ftlb to 912ftlb check bottle drop to 140bar .
Filled to 190bar 1 mag 905ftlb to 891ftlb . Bottle drop to 160bar . Both gauges on bottle and qf both read the same . But every time you put a new mag in the first shot is always low? . Sorry for all the questions but still new to the fac route
Do you mean the first pellet is hitting low?
One cause is your Mag...
The spring tension maybe set a bit high.
So it may be deforming the skirt of the first pellet(it experiences the Max spring tension!)
A simple spring adjustment may Help....
Follow my instruction on how to disassemble your mag....
https://rapidforum.co.uk/forum/index.php?topic=237.0
Move the spring over one hole anti(counter)-clockwise.
Test.....
Good Luck,
Stuart
Quote from: Richard 7310 on November 14, 2021, 12:16:36 PM
Hi all . OK filled up to 180 bar put one mag through . 928ftlb to 912ftlb check bottle drop to 140bar .
Filled to 190bar 1 mag 905ftlb to 891ftlb . Bottle drop to 160bar . Both gauges on bottle and qf both read the same . But every time you put a new mag in the first shot is always low? . Sorry for all the questions but still new to the fac route
Rough guestimate
@190 905....rising to 912?
@180 bar 928 i= 34ft/lbs - 912 = 33
@ 160bar you're getting 32 down to 29
You're getting a power curve of sorts as the velocity is dropping off at 190bar so max fill 185 bar, top up at 145-150?
But also velocity appears to be dropping steadily and TBH 40-45 bar is too much air for 18-20 shots.
32ft should get around 3 magazines -30 shots down to where it drops off the power curve. - plus a couple of shots either side of the consistency plateau with no real change in POI
Obviously without knowing what's inside; I have a feeling that 32-34ft/lbs is optimistic rather than optimal for what may be an otherwise standard FAC R7.
Personal experience would say that the unrestricted flow from the QF is allowing the air to overrun the valve rather than the valve controlling the air.
On mine although power went up 10% -the max fill dropped 5-10 bar and I had to detune to get consistency and shot count back.
I'd back hammer preload off maybe aim for 880fps or try 15.9 Exacts for 920ish- POI will be an inch higher at 60yds and still have 17ft/lbs....only down 1ft/lb.
I would hazard a firm guess that the shot count will go up and it'll be a lot quieter.
Thanks for that . I will look on you tube to see how to do it . Yes it's noisy when you fire , just thought maybe the silencer needs updating ? . But will try some other pellets . I did notice that 30m and 40m groups were very good . Go out to 50 m and the grouping is all over the place . And that's shooting with a bench rest . But thankyou for answering my questions .
You're welcome, apologies for jumping in at the deep end and pulling a diagnosis from very little. :-X
30-40m shouldn't be a problem with most ammo, you may have to try a few different pellets to get the 50m accuracy sorted.
Quote from: Richard 7310 on November 14, 2021, 09:12:20 PM
Thanks for that . I will look on you tube to see how to do it . Yes it's noisy when you fire , just thought maybe the silencer needs updating ? . But will try some other pellets . I did notice that 30m and 40m groups were very good . Go out to 50 m and the grouping is all over the place . And that's shooting with a bench rest . But thankyou for answering my questions .
these explain the power curve v fill pressure & hammer loading better than my rambling
https://www.pyramydair.com/blog/2008/12/understanding-the-performancepower-curve-of-a-pcp/
https://hardairmagazine.com/ham-columns/bobs-guide-to-tuning-unregulated-pcps/
https://hardairmagazine.com/ham-columns/using-hammer-strike-to-control-pcp-power/
Thankyou your a top man will look later .👌