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Author Topic: Chrono test  (Read 140 times)

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super moto

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Chrono test
« on: September 16, 2018, 07:09:05 PM »

Have just done a 30 string chrono test
Filled to 180 bar using unweighed kaiser in .177
780 FPS
763
734
11.47 ftlbs
11.00
10.18
Over 1ftlb difference and a 46fps vari.
I find this quiet shocking for 30 shots
Any ideas how to better this
Rifle used .177 bsa ultra mmc
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RANCiDTOM

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Re: Chrono test
« Reply #1 on: September 16, 2018, 10:42:21 PM »

Step 1, service it. Chrono it and see if it has improved.
Step 2 tune it or send it off for a tune. Consider a regulator as part of the tune. Simply slapping a reg in without making other tuning improvements won't help as much as tuning the gun so the reg can perform correctly. A gun tuned for a regulator is a very different set-up to one tuned for unregulated use. Some people fit larger air tubes but before you know it you've built yourself a Scorpion not an Ultra.
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super moto

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Re: Chrono test
« Reply #2 on: September 20, 2018, 10:58:12 PM »

A reg won’t give increased shot count it will just make the rifle more consistent between each shot.persononally I think a reg for 30 shots is not needed.
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RANCiDTOM

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Re: Chrono test
« Reply #3 on: September 21, 2018, 12:36:13 AM »

A reg can give increased shot count if it allows you to fill the gun to a higher pressure than the "sweet spot" of an unregged gun. We are talking useable shot count, not just shots that make it out of the end of the barrel, shots that won't require any holdover/under to account for variations in MV from fill pressure.
When a gun is correctly set up to work properly with a regulator it will not magically transform it (apart from flatten teh power curve) but it can make the gun far more efficient at the regulator pressure if it is correctly tuned for this pressure. As I said earlier, slapping a reg in to a gun which has been tuned to work across a range of pressures will not give optimum efficiency at the optimum pressure for the gun.
Changing hammer weight, spring, stroke length, transfer port diameter and various other aspects of the exhaust valve can make a massive change in the gun efficiency and hence more shots. Tuning a gun without a regulator is always a compromise for more shots in the power curve than it is set optimally for.
A properly tuned and regulated gun should have less than 10 feet per second variation from full fill pressure down to the pressure at which the regulator is set so long as all the other variables are set up correctly. In theory this is achievable, with an unregged gun there may be only a few shots which are truly 10 fps variation. By  10fps variation I mean +/-5 fps from the average.
You can set about finding the optimum for yourself, buy a kit and follow the instructions or pay a tuner to do the mods and the fitting for you, whether you go along the regulator route or the unregged route.
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super moto

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Re: Chrono test
« Reply #4 on: September 21, 2018, 01:19:18 AM »

I’ve just been looking on xtx website.apparantly you don’t need to use the bigger transfer port and hammer spring set up has the ultra mmc already has a bigger transfer port and softer hammer spring
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