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Author Topic: Regulators and Valves, oh my  (Read 208 times)

ncrary

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Regulators and Valves, oh my
« on: September 07, 2017, 04:46:09 PM »
I have been doing some research on regulators and valves.  If a guy was going to start from scratch with a Mrod 25 cal, what would be a good combination of regulator and valve to achieve best efficiency and shot count with a reasonable FPE?  By reasonable I mean something that will humanely dispatch squirrels and doves out to 100 - 150 yards.  There are so many combinations that I have been trapped in a fog of specs and numbers.  Help, Mr Wizard!


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rsterne

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Re: Regulators and Valves, oh my
« Reply #1 on: September 07, 2017, 07:02:03 PM »
Anything 100 yards and beyond, accuracy is going to be your biggest issue, rather than energy, IMO.... One of the most overlooked parts of accuracy is the wind, and to put it mildly,  pellets suck in windy conditions.... However, bullets are really in their infancy in their use in airguns, and accuracy for the most part is spotty.... When you get the right combination, it's magic, but generally elusive.... So at this moment in time, let's concentrate on pellets, and restrict our use to 100 yards, because anything beyond that, on squirrel size targets, will be more a matter of luck than planning or skill, IMO....  If you have your heart set on shooting bullets, with their superior BC, contact Nick at Nielsen Specialty Ammo for advice on his slugs for the MRod....

For pellets, my choice would be the 34 gr. JSB Exact Heavy Mk.II, provided you can generate the FPE to shoot it fast enough with the 20" barrel in an MRod.... My BRod using the Cothran valve has a 24" barrel, but at 1900 psi I can get into the mid 900s with decent efficiency.... With your 20" barrel, you should be able to get into the high 800s, and luckily that velocity tends to be very accurate with those pellets.... Therefore, that would be my goal.... something in the 58-60 FPE range with the 34 gr. JSBs....

I have NOT used any of the in-tube regulators, so I can't make a recommendation on them.... Travis or Scott would be the guys I would ask, if I were going to build an MRod like that.... and I would pay attention to their recommendation on plenum volume, setpoint, and hammer weight.... I would certainly be looking at the new ART/Sikes "SS" valve, regardless of the regulator I chose.... If you are going to build a bottle gun, then the regulated tank block from WAR, which is externally adjustable, would be my first choice.... Any other route you take will require a tear-down if you need to change the setpoint.... which you will NEED to do if you use my second choice, the Cothran valve.... The Powerhouse valve has huge ports, and can deliver the FPE you want, but you MUST change the setpoint pressure to change the velocity.... That is why I would go with the new SS valve.... you can set the power range with the setpoint pressure, and then fine tune it with hammer strike.... Either of those valve are balanced, so will have much less hammer strike required than an MRod based valve....

If you get the new SS valve from Travis, tell him your FPE goal, and ask him if larger ports would be better to achieve it.... The stock ports are 3/16", and going larger will require you to drill out the main tube and receiver for a large OD transfer port.... Larger ports will allow a lower setpoint, which could increase the shot count.... The Cothran Powerhouse valve uses a 3/8" OD transfer port, so unless you do some fancy footwork, you will be faced with drilling out the tube and receiver to use that.... Ultimately, your choices may depend on how many mods you are willing to accept, and if you can do them yourself, or have to pay to get them done for you....

Bob
« Last Edit: September 07, 2017, 07:04:00 PM by rsterne »
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ncrary

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Re: Regulators and Valves, oh my
« Reply #2 on: September 08, 2017, 08:43:26 AM »
Thank you.  That is good food for thought.  I m not in a hurry for this project, so I have time to explore different avenues. I had not thought about bottling this gun, but that may be a good consideration to look at for ease in adjustment.
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