NEW GUY RESULTS

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TNHunter

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Jan 7, 2016
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TN
So.... finally got my replacement synthetic MRod .25 from Pyramid (the first one was leaking as much as 600 PSI overnight).

20160126_212427_zpshnr5gxrb.jpg


And have done some initial shooting.

Screenshot_2016-02-27-15-49-41-1_zpsaw5nt53m.png


And this was my results at rest (resting the gun on a table to shoot *no bench*), 35yds...

20160227_150759-1_zpsfqgj6oza.jpg


There's a couple of flyers in there, was adjusting my rest too.... Hey! I never said I was a sniper!



But I've got a couple questions.

I bought the small Air Venturi tank from Pyramid (90cu in) and have had it filled, and checked, multiple times at the scuba shop close to my house. I'm pretty dang sure it's filled to 4400PSI .... and when I go to fill the gun it says on the gun gauge that I'm filling to 2000 PSI and it won't fill any further. Then I pull out the hand pump (Benjamin) and manually finish filling it to 2900 PSI. And when I start the gauge on the gun says 2000 - 2200, but the valve doesn't "tick" and start filling while pumping until the pump crosses around 2500 PSI. At the end, the gun says 3000 or so, and the pump says 2900.

But why the heck can't I get the tank to fill it to that level? Do I need to just leave it on longer? I mean it'll go from 1000 to 2000 in seconds, and doesn't seem to go any further.....

What gives?!

Also, is it normal for these guns to lose pressure? This one certainly doesn't leak like the first one, but it still loses pressure over night just sitting in the closet.
 
I guess the question is.... how far off can the actual pressure be between 2 different gauges? The rifle gauge I expect to not be that accurate, but the pump gauge and the rifle gauge seem to line up in the end.

Would the rifle lock up at 3500PSI if they were both off and I was over filling past 2900? Assuming the bottle is actually filling the rifle to 2900...
 
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I had the same problem with my gun having a slow leak. i'd check all the o-rings in the air cylinder but must likely culprit is the gauge assembly. Put some teflon tape and make sure the gauge and the gauge extension piece are tight. Disassemble the gun down to just the air cylinder with a normal charge of air and give it a dip in the bathtub. 

Its hard to say how "off" a guage can be unless its a calibrated item. I put more expensive 5000psi gauges in my pumps that have a 2%-1%-2% rating. Basically its within 1% of shown pressure in the middle range where you would normally be filling you gun too. Can always replace the one in the gun too, but havent really seen a rating on those little gauges. ones i have are ususally 100-150 off from my pumps. 

3500 psi isn't really a good idea. Besides the safety factor, it may or may not valve lock, but your shot bell curve will be shooting really weak till your spring and hammer over come the pressure against the valve and it gets to the top of the bell curve. Was 860fps the first or last shot you took?
 
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TNHunter I can't help you much with your air tank filling problem but it appears you do not have a bell curve going for your fps. If the #1 and 868 fps is your first shot and your next shots continue to fall in fps it suggest you have filled your rifle at too high a pressure a starting pressure. Try filling your rifle to different starting pressures like 2600 or 2700 or 2800 psi and do a shot string of 16 shots. Then see if your fps curve starts lower and then rises and then falls back again. Record each fps and then try a different starting fill pressure and try another shot string. Then choose the starting fill level that gives you the best fps curve and velocity extreme spread. I see with the stock .25 cal. Mrod you can expect to get about 16 shots per fill. The airgun site that will really help you with the Mrod tuning is here
http://www.marauderairrifle.com/forum/ 
 
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 Wrong regulator.
They did have the discovery regs for a while, "2,000psi" and for some reason ( ????? ) the 2,000psi unit has a "1,800psi" burst disc - which seems very odd to me - not that it guarantees anything but what are you burst disc's marked as? IF you have a 5,000psi HIGH side disc and a 1,800psi low side disc it IS the discovery regulator.
Verifie the 2,000psi number using another rifle or? Then you'll likely need to return it. 

You could if you wanted to , rebuild/reset the regulator not a hard job, use the Ninja Paintball youtube video and order some bevelle washers and a higher burst disc if needed. Might be cheaper than returning the entire un it.

And even if you get the reg right it is still designed for a 2,900psi MAX.


John 
 
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"AirgunBill"TNHunter I can't help you much with your air tank filling problem but it appears you do not have a bell curve going for your fps. If the #1 and 868 fps is your first shot and your next shots continue to fall in fps it suggest you have filled your rifle at too high a pressure a starting pressure. Try filling your rifle to different starting pressures like 2600 or 2700 or 2800 psi and do a shot string of 16 shots. Then see if your fps curve starts lower and then rises and then falls back again. Record each fps and then try a different starting fill pressure and try another shot string. Then choose the starting fill level that gives you the best fps curve and velocity extreme spread. I see with the stock .25 cal. Mrod you can expect to get about 16 shots per fill. The airgun site that will really help you with the Mrod tuning is here
http://www.marauderairrifle.com/forum/ 
Click to expand...
Thats not correct. If the rifle was filled to high for what the HS pre load was set and the HT was set at then it would be partially valve locked causing very low initial shots and climbing to a peak and then back down. If he keeps the settings as they are for that string and lowers his fill pressure he will only cause the string to be worse and less shots. If you have a declining string you need to either increase the fill pressure or lower the hammers energy by adjusting the HS and or HT.
 
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