Calling all 25 cal marauder REGULATED guns

[shorty]

Great job-string looks good to me. Another one added to the 40/40.

A little advice to people thinking about doing this 40/40 tune or just regulating their Mrod, do yourself a favor and get a new pressure gauge. This is my second Mrod and now it's going to be my second pressure gauge. Mine took a dump.

When is crossman gonna splurge for something better than this cheapo pressure gauge that fails continuously ? So disappointing some times.

[ezman604]

Yep, I replace mine with these...
http://www.ebay.com/itm/171826034342?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

[WHITEFANG]

Good work!! The low numbers can be thrown by inconsistent pellets sizing. 40 shots is great for that gun.

So you are using the SSG with the light spring and how light of a hammer? Assuming I may have missed that you are using the lightweight valve spring?

[ezman604]

Yep, lighter weight valve poppet spring. One you can actually operate the poppet with your finger, something you cannot do with the OEM spring.
This hammer is 42gram in weight. Down from the 77gram OEM hammer. And it makes much better power, accuracy and more stable results with the JSB MKII 33.95gr rounds.

[ShawninIL]

That's great!! Might need another .25 Mrod to have 2 regulated .25s 

Just bought the .25 that Travis used for testing the TSS

[Dairyboy]

That's great!! Might need another .25 Mrod to have 2 regulated .25s 

Just bought the .25 that Travis used for testing the TSS

You lucky dog!! In assuming it came with the TSS huh?

[ShawninIL]

That's great!! Might need another .25 Mrod to have 2 regulated .25s 

Just bought the .25 that Travis used for testing the TSS

You lucky dog!! In assuming it came with the TSS huh?

Yep and fully tweaked and tuned by the man himself. Should be on the way today.

[Dairyboy]

That's great!! Might need another .25 Mrod to have 2 regulated .25s 

Just bought the .25 that Travis used for testing the TSS

You lucky dog!! In assuming it came with the TSS huh?

Yep and fully tweaked and tuned by the man himself. Should be on the way today.

Nice buy for sure! Let us know how it is

[Zachary Hoy]

I wanted to say thank you for everyone who contributed to this thread and provided the info to help me join the 40/40 club. It was a fun road to travel ending in success.

Description: Synrod .25/reg/135bar/Hill valve, hammer, striker
Notes 1: lightest valve spring, 262 hammer spring, bored out to .187
Notes 2: Polished tube, Bolt probe thinned, hand lapped barrel, gen 2
Distance to Chrono (FT): 6.00
Ballistic Coefficient: 1.000
Bullet Weight (gr): 25.430
Altitude (FT): 0.0
Temp: 52 °F
BP: 29.95 inHG
Shots
#     FPS        FT-LBS     PF
40    829        38.81      21.08     
39    831        39.00      21.13     
38    834        39.28      21.21     
37    843        40.13      21.44     
36    838        39.66      21.31     
35    842        40.04      21.41     
34    844        40.23      21.46     
33    838        39.66      21.31     
32    844        40.23      21.46     
31    841        39.94      21.39     
30    850        40.80      21.62     
29    849        40.71      21.59     
28    845        40.33      21.49     
27    843        40.13      21.44     
26    837        39.57      21.28     
25    840        39.85      21.36     
24    834        39.28      21.21     
23    837        39.57      21.28     
22    836        39.47      21.26     
21    832        39.09      21.16     
20    837        39.57      21.28     
19    831        39.00      21.13     
18    833        39.19      21.18     
17    833        39.19      21.18     
16    836        39.47      21.26     
15    835        39.38      21.23     
14    842        40.04      21.41     
13    845        40.33      21.49     
12    846        40.42      21.51     
11    846        40.42      21.51     
10    843        40.13      21.44     
9     844        40.23      21.46     
8     845        40.33      21.49     
7     839        39.75      21.34     
6     847        40.52      21.54     
5     848        40.61      21.56     
4     827        38.63      21.03     
3     830        38.91      21.11     
2     831        39.00      21.13     
1     828        38.72      21.06     
Average: 838.83
StdDev: 6.35
Min: 827
Max: 850
Spread: 23
True MV: 839.40
Shots/sec: 0.00
Group Size (IN): 0.00

[shorty]

Another success story.

Sounds like this 40/40 is starting to be the norm.

I think it's getting time to start developing that (drop in) extra plenum to take this 40/40 tune to the next level.

[David9862]

I wonder if it would be possible to get 24/50, 32/45, and 40/40 by just changing the gap on ssg.  It would be nice to have like a single adjustment that could adjust power like that.

[GoneShootn]

I wonder if it would be possible to get 24/50, 32/45, and 40/40 by just changing the gap on ssg.  It would be nice to have like a single adjustment that could adjust power like that.

40 shotsat 40 FPE would be a total of 1600 FPE for the fill. Wouldn't the equivalent at 50 FPE/shot be 1600/50 = 32 shots at 50 FPE/shot? If so, I wonder if that would be doable, perhaps, as David suggested, via adjusting the SSG?

[FuzzyGrub]

I wonder if it would be possible to get 24/50, 32/45, and 40/40 by just changing the gap on ssg.  It would be nice to have like a single adjustment that could adjust power like that.

40 shotsat 40 FPE would be a total of 1600 FPE for the fill. Wouldn't the equivalent at 50 FPE/shot be 1600/50 = 32 shots at 50 FPE/shot? If so, I wonder if that would be doable, perhaps, as David suggested, via adjusting the SSG?

In general, all things equal, if you are going to a higher fpe, the efficiency will decrease, and you will not achieve the math you stated.   

[GoneShootn]

I wonder if it would be possible to get 24/50, 32/45, and 40/40 by just changing the gap on ssg.  It would be nice to have like a single adjustment that could adjust power like that.

40 shotsat 40 FPE would be a total of 1600 FPE for the fill. Wouldn't the equivalent at 50 FPE/shot be 1600/50 = 32 shots at 50 FPE/shot? If so, I wonder if that would be doable, perhaps, as David suggested, via adjusting the SSG?

In general, all things equal, if you are going to a higher fpe, the efficiency will decrease, and you will not achieve the math you stated.

Given what is being done at 40+- FPE, I wonder that might be doable, then, at 50 FPE or 60?

[FuzzyGrub]

To get to the current 40/40, significant valve modding or aftermarket valves were used.  Not much more room left, so most likely your shot count will be lower than prediction.  Also, as mentioned by Shorty, plenum size is going to come into play.   So if you didn't have the "chamber ext" he mentions, then that will cost you airtube volume and shot count loss. 

Typical hunting, not going to need as many high power shots.  Even this 40/40 is overkill for typical hunting. 

[addertooth]

Zachary Hoy,
Turn down your regulator pressure to 125-129 Bar and your extreme spread will go down.  In your posted shot string your velocity goes up as you start to come off the regulator, a sign your regulator pressure is too high.  As well as your ES going down, you may discover you get a couple more shots as well (and it looks like your average velocity will go up as well).  This is assuming you leave all other adjustments exactly where they currently are.   Best of luck.

[rsterne]

Generally, in a regulated PCP, as you increase the FPE requirement, you need a higher setpoint pressure, or the efficiency suffers.... even if you can attain the higher FPE level.... This means that the typical trade off in FPE and shot count you see in an unregulated PCP doesn't often apply.... As you increase the setpoint pressure to achieve the higher FPE, you lose "headroom", ie the amount of HPA available between your fill pressure and setpoint, and that costs you directly on shot count.... For instance, if you increase the setpoint from 1800 psi to 2200, on a gun with a 3000 psi fill, the headroom in the HP side of the regulator decreases from 1200 psi to 800 psi, which relates to a direct 33% loss in the air available to produce shots.... Factor in that your shots are now more powerful, and each one requires more air, and the shot count drops dramatically, even if the efficiency remains the same.... If you don't increase the plenum size, you are likely to lose efficiency at the increased FPE level, further reducing shot count.... and if you do increase the plenum size, you lose even more air on the HP side, which again loses the ability to produce shots....

In a nutshell, that is the basic reason that regulated PCPs are more suitable for low to medium power applications.... The exception is if they are specifically designed, from the ground up, for a high-power application.... with a large bottle and a large plenum....

Bob

[ezman604]

Just finished the bench work on this one. Can use a bit of tweaking to fine tune it. But what was done was an Audrius regulator set to 2100psi installed. Gauge block opened up, valve input cap opened up, poppet stem necked down and lighter poppet spring. Valve output port opened to 0.165". TP and barrel port both opened to match.
Light weight hammer added with internal SSG and medium weight spring. External power adjuster added. Power adjuster set for approximately 2 turns out for a starting area of 830-840fps with 25.39gr JSB rounds. Here's a 40 shot string. Ending pressure 1750psi.

I'll add that this one has lots of adjustability as far as power. It can be turned up and I've seen it slam out 33.95gr JSB at 57-58fpe. It can also be turned down for lower power and a much longer shot string. The SSG spring preload can also be tweaked. And one last shameless plug, this one will be available soon in a classified gate near you.




  1   831   38.94
  2   844   40.17
  3   831   38.94
  4   848   40.55
  5   835   37.45
  6   839   39.69
  7   847   40.45
  8   837   39.5
  9   831   38.94
10   838   39.6
11   833   39.13
12   816   37.55
13   807   36.72
14   823   38.19
15   826   38.47
16   814   37.36
17   834   39.22
18   831   38.94
19   826   38.47
20   823   38.19
21   827   38.56
22   823   38.19
23   826   38.47
24   840   39.79
25   835   39.31
26   833   39.13
27   837   39.5
28   835   39.31
29   833   39.13
30   827   38.56
31   821   38.01
32   826   38.47
33   837   39.5
34   835   39.31
35   833   39.13
36   831   38.94
37   827   38.56
38   826   38.47
39   821   38.01
40   820   37.45

FYI and to answer the question about being able to get results from simply adjusting an SSG assembly.
Yes...it can be done quiet easily. The above string was made with the MRod after installing the Aurdius regulator set to 200-2100psi. PERSONALLY, I can't see regulating anything above .20cal. Now, to me, anything above that caliber has a primary mission that includes hunting. And if hunting, I'm not concerned with getting 40-50 shots. I want at least 2 clips at max power and range. But hey, that's just me.
This same MRod that posted these numbers above posted these numbers below. This is without the Audrius regulator but with the light weight hammer and internal SSG. Turned up, this one can crank out 56-58fpe from JSB MKII 33.95gr for at least 2 good magazines. Simply turning the power adjuster down will give you a much longer string at reduced power. Virtually the same as the regulated airgun IMO.
I had a regulator laying around and to post in this thread, I installed it just to see. I'm still convinced the right internal modifications with an internal SSG and power adjuster is the way to go.
I've almost got my schedule of projects cleared and will be benching all of my MRods and Discos soon to make these same internal improvements.
Here's the string unregulated and achieved by simply adjusting the SSG.

#     FPS        FT-LBS
1     748        42.19
2     766        44.24
3     778        45.64
4     790        47.06
5     794        47.53
6     795        47.65
7     801        48.37
8     799        48.13
9     814        49.96
10    821        50.82
11    831        52.07
12    823        51.07
13    830        51.94
14    837        52.82
15    827        51.57
16    841        53.33
17    851        54.60
18    840        53.20
19    850        54.47
20    846        53.96
21    836        52.69
22    845        53.84
23    839        53.07
24    833        52.32
25    822        50.94
26    814        49.96
27    813        49.84
28    808        49.22 
29    803        48.62
30    788        46.82
31    791        47.17     
32    775        45.29

[Zachary Hoy]

Zachary Hoy,
Turn down your regulator pressure to 125-129 Bar and your extreme spread will go down.  In your posted shot string your velocity goes up as you start to come off the regulator, a sign your regulator pressure is too high.  As well as your ES going down, you may discover you get a couple more shots as well (and it looks like your average velocity will go up as well).  This is assuming you leave all other adjustments exactly where they currently are.   Best of luck.

What would you suggest another 5 bar? That was the very first 40 shots after installing the regulator and es has tightened up. I do however have that spike still. NM I missed the first sentence somehow. My apologies

[shorty]

Here's my 50fpe tune. Easily do-able with just 2 turns on my hammer spring.

33.95 grain JSB's

Shot   FPS   FPE
1   814   50.0
2   824   51.2
3   827   51.6
4   825   51.3
5   825   51.3
6   826   51.4
7   817   50.3
8   825   51.3
9   812   49.7
10   817   50.3
11   810   49.5
12   814   50.0
13   812   49.7
14   822   50.9
15   815   50.1
16   824   51.2
17   827   51.6
18   827   51.6
19   820   50.7
20   823   51.1
21   825   51.3
22   825   51.3
23   816   50.2
24   818   50.5