Calling all 25 cal marauder REGULATED guns

[shorty]

There's been a bunch of us guys regulating the 25 Mrod lately with some unbelievable shot count and power levels never thought to be achieved. The posts to follow our progress is challenging to follow since they are beginning to spread throughout the forum.

It would be great for all of you that have regulated or in the progress of regulating your 25 Mrod to post your strings here in one place so that we can have a historical shot count/fps/fpe post for us guys that have regulated our guns and to help each other improve them even more.
And,
Use this post for guys that are planning on regulating for them to see what they can expect from a 25 cal regulated Mrod.

Just a simple chart of the shot count with fps or fpe or listed out along with reg pressure setting. Starting and end fill pressure. A general listing of the guns mods.

Like this:
Huma (with gauge port) regulator set at 1900/1950psi
Hogged out valve with .196 porting through and through.
Custom hammer spring and poppet spring.
Stock air tube and stock hammer.
Start pressure 3000 end pressure 1900psi for both strings.

[Finchlake]

I'm looking forward to following this thread. I have 2, .25 Marauders and this is the next Mod I want  to try.

[rsterne]

If I could make a suggestion, including the plenum volume would be a useful piece of information.... It affects the efficiency, and also the remaining reservoir volume.... This allows easier comparisons.... JMO....

One other comment regarding the 40 FPE string above.... The velocity increase at the end of the string is indicative of shooting past the regulator setpoint.... Either the regulator is set higher than you think, or the pressure when you stopped shooting is lower.... The setpoint was reached not later than shot 36.... The proof is in the velocities....

Bob

[shorty]

Bob,
I noticed the same thing in the 40fpe tune. When I chopped it in excel I caught all the data when converting it from FPS to FPE. I agree to with plenum size. I was just to impatient to take measurements before dropping in the reg. There has been rumor of 22/24CC's with a hogged out valve using this gauge style Huma regulator which puts the high pressure side just at or close to 190cc.


Raw data on 40 FPE tune:
Shot   FPS   FPE
1   719   39.0
2   725   39.6
3   722   39.3
4   718   38.9
5   719   39.0
6   723   39.4
7   720   39.1
8   717   38.8
9   719   39.0
10   724   39.5
11   728   40.0
12   719   39.0
13   725   39.6
14   727   39.9
15   720   39.1
16   726   39.7
17   734   40.6
18   736   40.8
19   718   38.9
20   725   39.6
21   731   40.3
22   724   39.5
23   726   39.7
24   721   39.2
25   719   39.0
26   724   39.5
27   734   40.6
28   733   40.5
29   736   40.8
30   733   40.5
31   733   40.5
32   729   40.1
33   717   38.8
34   734   40.6
35   728   40.0
36   734   40.6
37   740   41.3
38   744   41.7
39   755   43.0
40   765   44.1

I know how you like to look at the knee (and so do I now) so here's the knee in the chart. From the knee, 50 fpe is the max I would want to run with any kind of efficiency and around 44 to 46 fpe would be ideal to get the additional shots off regulation. I was using the 33.95 grain JSB's

As soon as I get some 25.39's I plan on a backyard tune of around 35-38fpe for a minimum of 50 shots on regulation. Just got to get them on order first.

[3BI5]

Here's some of my late season 2015 setup strings with 25.39gr JSB's.
The gun is .25 synrod with reservoir extension, total air capacity 215cc+73cc or something like that.
Huma reg with hogged out marauder gauge port, hogged out stock valve, total plenum volume about 22-23cc. Transfer port .187. First gen WAR NBH with 10 or 12lbs hammer spring.
Regulator set pressure 2000psi.

1. string is low tune, 819fps/37fpe avg, 3200-1200psi (red string)
2. string is 870fps/43fpe avg, 3200-1620psi
3. string is 895fps/45fpe avg, 3200-1800psi (red string)

[rsterne]

shorty, if the plenum is 25 cc, you won't have 190 cc of reservoir left, because the regulator itself takes up some of the tube volume.... A stock MRod is 215 cc, and the reservoir is 14.5 cc per inch of length, so if the regulator takes up 1" of length, that is another 14.5 cc you have to deduct from the reservoir.... Of course if you remove the gauge block, you gain back that lost volume....

Bob

[FuzzyGrub]

Bob,

I don't believe that the 215cc in a Gen II includes the gauge block.   There are 15.5" between gauge block and fill assy.  With an ID of 1.050", puts it slightly over the 215cc.  The airtube reservoir portion on Gen II is about 5/8" longer than Gen I.

[shorty]

So,
Are we all on the same page of 190cc of volume with the Huma gauge port assembly regulator ? I really enjoy seeing those efficiency numbers hovering around 1.7 with a 25 Mrod at 38/42 fpe .

FuzzyGrub took these measurements on his:
Main Body
L: 3.035"
D: 1.050"

Top/adj
L: 0.625"
D: 0.520"

Bob,
Can you look at he numbers and re-check for me?

[rsterne]

John, you are correct, the Gen 1 reservoir volume is 215 cc from the front of the gauge block to the fill plug.... What I meant was that I don't see how the reservoir could be 190 cc if the plenum is about 25 cc and the gauge block is still in place, because the regulator itself has to displace some of the reservoir volume....

shorty, I assume those are the measurements on the regulator?.... The "main body" volume is 43 cc, and the "top/adj" volume is just over 2 cc.... That will reduce the 215 cc reservoir to just 170 cc unless you are removing the MRod gauge block, which increases the reservoir volume of course.... It is 1.46" long, so that increases the reservoir 21 cc if you remove it (plus any space between it and the valve).... I assume the plenum volume is within the 43 cc main body?....

My question would be.... are you removing the gauge block?.... If so, yes your reservoir is just over 190 cc....

Bob

[FuzzyGrub]

Yes, the Huma they are using replaces the gauge block:

http://www.huma-air.com/Benjamin-Marauder-pressure-regulator-with-pressure-gauge-connection

It has a "donut" on the inside where the gauge screws in, so a liquid measurement for plenum volume would be the best way to measure.  But, here is what I can measure:  Plenum H: 2.475" X ID 0.695 - (Donut (H: 0.530" X D: 0.695") - Donut Hole (H: 0.530" X D: 0.225"))
= 0.7589cu in or 12.44cc + what is in the valve, so it is way undersized to BobR recommendations.

PS: I'll re-measure and re-calculate tonight

See my air res calculations on #36 and #38: http://www.gatewaytoairguns.org/GTA/index.php?topic=115601.20

I got 188cc.

[shorty]

Goody on the 190cc reservoir.

Now let's see some more 25 cal Regulated Mrod tunes. 3BI5's string looks awesomely long with that reservoir.

[Sfttailrdr46]

Bob what would be the optimum plenum for a .30 caliber Marauder

[rsterne]

I like to use 1 cc per FPE if you have an external reservoir (bottle) where the volume is unaffected by the plenum size.... When you are using an internal regulator, inside an existing reservoir tube, going that large will reduce your reservoir volume too much.... You can go down to 1/2 cc per FPE and the only downside is that you have to run about 10% higher setpoint to compensate for the pressure loss during the shot cycle from having a smaller plenum.... If you go smaller than 1/2 cc per FPE, you will either lose power, or efficiency, or both, or you will have to crank the setpoint up so high your shot count will suffer....

There are exceptions to every rule, and the more efficient the setup, the more tolerant it will be of a small plenum volume.... My regulated .30 cal XS60C uses a plenum that is over 100 cc.... and it reaches 100 FPE at 2200 psi setpoint with 14 shots (2 clips) from a 22 CI tank.... If you have any more questions about plenum size, best to start another thread, rather than hijack shorty's.... To answer your question, I would not build a regulated .30 cal MRod using just the stock reservoir, I think you would be disappointed in either the power or shot count....

Bob

[FuzzyGrub]

Now let's see some more 25 cal Regulated Mrod tunes.

I should have something in about a week.  I decided to put the 25 cal top on my reg'ed 22 first.  The reg was set at 2200 (initial).  This is an Audrius reg with semi-hogged out gauge block.  I need to add some weight to Scott's LW hammer.  Also a zero pre-load double spring.  After that, will put in the Huma and see what that does.   

[Sfttailrdr46]

No hijack intended and I have another .25 Marauder to play with Just wondered what the optimum Plenum was

[shorty]

I think all these things are really important to put out there.

I also think a little different than Bob in regards to plenum sizing but, we all tune differently with different results.

For me, when calculating plenum size, I use 2 times the barrel and all the porting volume after the valve as a plenum size. I also calculate the plenum size based on PRESSURIZED volume vs atmospheric pressure volume since the plenum is under pressure.

I do agree that a larger plenum is optimal (for power) but, with the limitations of an in tube regulator dictates along with your efficiency, your shot count.

Now,
For versatility, I have been pondering about a regulator by-pass valve for 60+ fpe for our 25 cal marauder using this Huma regulator. This may also be used in a 30 cal conversion were you can shoot 20 regulated shots at 60 fpe or hit the by-pass valve and blow 80+ fpe for one mag.

I have the idea my head but I am not confident of my skills messing with HPA tubing and hardware. The thought process would be to T-off at the fill into the gauge port assembly with some type of valve in between. Not a bad idea if you can fit it in the stock to hide.

[fsa46]

I was hoping this thread would take off. I'll bet I'm not the only one that's disappointed  it hasn't. 

[cclingma]

I'm watching closely too.

40 shots at 40fpe.  The 4040 tune.

[mobilemail]

I'm watching because I'm not only interested in the 4040, but I'm also thinking what this could do to transform a .22 mrod. 6030 (60 shots @ 30fpe regged)?

[anti-squirrel]

I dunno.. I'm learning a lot by doing what I used to do these last 3 years (prior to joining)... reading and thinking.  I still take everything with a bit of a grain of salt- not as a Doubting Thomas but as a guy who doesn't have the money to play at these levels, and has to shoot these tuned guns vicariously   Results on the Chronograph always speak loudest, though putting all that power and efficiency into pellets means nothing if accuracy isn't a partner.

Shorty and Bob- thanks- great insight as always.