Air arms s500 bell curve

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sean48855

sean48855

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Feb 14, 2016
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Michigan, United States
Hi all I am new to the pcp world I have picked up a syn rod in .25 and a s500 in .177 and have been hunting and plinking with both for about a year I recently just got a chrony and my s500 with the power adjuster at just under half (best accuracy in my gun) has a average of 895.5 es 3.38 sd 1.0 for first 10 shots with a 200 bar fill then starts dropping from there could I fill to slightly higher pressure say 220 to try to get more shots per fill?
 
The best starting fill pressure for the S500 series is around 190 bar. If you shoot full string you will starting at 200 bar you will see a dip, then a rise, then a dip again. Starting from 180-190 you should only see 1 rise and 1 fail. I have and S510 .22 FAC and i get the best result starting at 190 bar (2755 psi). I can get 4 clips. I believe the issue with the original drop is the hammer spring trying to over come the pressure put on it from the air tube.
 
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Two things about over pressurising.
1. The increased pressure increases the force on the firing valve. This (a) reduces the ability of the hammer to open the valve, resulting in lower fps, and (b) causes the firing valve seal (top hat) to deform giving permanent reduced performance.
2. And most importantly, I believe the cylinders MAXIMUM SAFE WORKING PRESSURE IS 200 bar.
 
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Aa_limited at a 200 bar fill my shot string is decending so filling to 190 would just give me fewer shots at a lower starting velocity or that's what I'm thinking I may be wrong I may be ordering a reg from the company ambushsniper recommended but like I said my first 10 shots appear to be the sweet spot with a of less than 5fps then it gets worse from there
 
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"aa_limited"pointlees to fill above 190 to an un modafied s510 completly pointelss, i think every one could agree on that.
Click to expand...
I would normally agree with this statement, but the OP said his string is flat and then tapers downward. If this is the case, wouldn't increasing the fill pressure not give him the upward part of the curve he is looking for? Not (imho) the best way to do it, but it should increase his "count" of usable shots. (w/i a certain percentage)

Sean you can't "adjust" the hammer spring, To decrease the pre-load you will have to cut the spring. What I would do first is remove the rear spring spacer and see what the string looks like.
 
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Not hard at all. You need a 5mm hex wrench to take off the single bolt screw.
You then need a 2.5mm and a 3mm to remove the 6 screws that hold the breech on. And a 1.5mm to loosen the barrel to tube band. The 5mm also takes off the rear block screw.

Start at about 1:50 in the below video and watch to 2:50.

Then go to part 3 below and watch till 1:15. At this point you will see the small aluminum spacer attached to the spring as Matt takes it out of the block. While you are in there I would polish up the hammer rod so that the hammer slides freely.


You don't need to take off magazine adapter
You don't need to take off the trigger guard

I just watched these about 5 times yesterday as I just put a regulator in my S510 Carbine. I took mine apart about 10 times yesterday getting the tune right for the pressure the reg was set at. I wound up cutting off about a coil and a half of my spring. I'm now getting 40 shots w/i 2% between 24 and 27FPE depending on the pellet.
 
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"sean48855"Sweet thank you for the links I watch a lot of his videos im surprised I haven't seen these ones do you feel that the reg was worth the money and effort as I am thinking I may go that route
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Worth it? The Audrius reg I got was $69. It took a couple hours to install and tune. Hardest part was getting the nerve up to drill the vent hole in my air cylinder.
Before the reg I got:
27 shots at 26.3fpe w/i 4%
17 shots at 26.8fpe w/i 2%
10 shots at 27fpe w/i 1%

After reg I get 40 shots w/i 2% and 30 of those were w/i 1% - this is was cheap CPHP pellets right from the tin. I think once the reg gets broken in and I use some decent pellets all 40 shots will be w/i 1%.
Power level -
14.3 (880fps) - 24.6fpe
15.9 (860fps) - 26.1fpe
18.1 (820fps )- 27fpe

I say WELL worth it.
 
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Okay here is my 30 shots fired over chrony master beta after seeing Johns shot curve my looks normal my gun is all stock fac .177
1) 897.7 200bar
2) 896.2 1-10 es 3.3 sd 1.0
3) 893.4. 11-20 es 5.2 sd 1.4
4) 893.4. 21-30 es 18.16 sd 5.65
5) 894.8
6) 896.3
7) 895.8
8) 895.7
9) 896.8
10) 896.4
11) 893.9
12) 889.3
13) 887.7
14) 885.7
15) 889.4
16)887.5
17)887.2
18)885.1
19)887.5
20)890.3
21)882.6
22)877.0
23)875.7
24)872.4
25)872.3
26)868.7
27)864.5
28)868.4
29)866.4
30)866.9 150 bar
 
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