Don Cothran M-Rod Power House Valve
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Don Cothran M-Rod Power House Valve
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Topic: Don Cothran M-Rod Power House Valve (Read 49949 times))
lloyd-ss
Bob and Lloyd
GTA Senior Contributor
Posts: 3567
Real Name: Lloyd
Don Cothran M-Rod Power House Valve
«
on:
May 27, 2016, 09:30:09 AM »
This is a diversion from the max vel project that has been consuming most of my airgun time.
Don Cothran has been around for a while and has a good, and well-earned reputation. At the recent Fun Shoot in KY, Eric from OH had a Disco based rifle with a Don Cothran Power House valve in it. Eric was singing the praises about it, and I have to admit that it seemed to make scary amounts of power. Then I was talking to my buddy Mark in TN and he had one of these valves in a Disco platform, too! He was saying the same things that Eric was. They both were saying: lots of power, and, very light hammer strike. Hmmmm. How could I resist. I ordered one online, but before it shipped, Don and I talked on the phone and he was talking about the M-Rod version, so I changed my order to the M-Rod valve. Its a little more expensive, but still very reasonably priced for what goes into this valve.
Don said he had been working on these balanced valves for quite a while to get them to where he was happy with them. This is Don's design and his intellectual property, so I will definitely not be taking it apart or showing any pictures other than the outside. I know the blood, sweat and tears that go into something like this.
Just looking at it you can tell it was designed for making power. I think it would be a waste on a .22 or .25 cal (but I could be wrong). A conversion that shoots .257 bullets or .30 cal pellets or the new .357 pellets, or bullets, or maybe even larger, will most likely be necessary to get the benefits of this valve. I am not expecting much in the way of air efficiency, but we'll see.
Here are some teaser pics. Pretty stuff !
Aluminum body with some nice brass detail parts. The exhaust port looks huge, and it is huge at .257 dia. The O.D. of the T-port will have to be .375 to fit properly, which means the hole in the tube will need to be opened up also, along with proper porting of the barrel. The stem is about .175 dia and protrudes about .200.
I've got some ideas for this and it will take a while to go through the process. The starting point will be a .25 cal Gen1 M-Rod, although it might end up on a Gen2 instead. Because the valve is supposed to need such a light strike, I've got a WAR SSG, and I also have a lighter hammer (54 grams vs 78 grams stock) that I made a while back, if that is needed, too. .257 and .30 cal barrels are on hand to try. Plus bigger if it "wants" them. I am getting excited about trying this out.
Lloyd
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Central Virginia
An engineer by nature. The affliction is knowing that everything can be made better. It is easy to make one that works, but it is difficult to make on that works WELL.
My YouTube channel is Airgun Lab
David Mccann
Sharp Shooter
Posts: 527
Real Name: david
Re: Don Cothran M-Rod Power House Valve
«
Reply #1 on:
May 27, 2016, 09:41:03 AM »
looking forward to seeing the results. congrats on your new valve.cheers
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deer lodge TN.
well, it's on the first walking cart out of east Egypt on friday, next week.
http://s1190.photobucket.com/user/davidmccann1969/slideshow/
MichaelM
BrewMunkey
Expert
Posts: 1099
Xenia,Ohio
Re: Don Cothran M-Rod Power House Valve
«
Reply #2 on:
May 27, 2016, 10:45:59 AM »
that looks like a thing of beauty.....
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Norm_m
GTA Senior Contributor
Posts: 2952
Real Name: Norm
Re: Don Cothran M-Rod Power House Valve
«
Reply #3 on:
May 27, 2016, 11:48:08 AM »
Well I am glad to see Lloyd has one of Don's Marauder Power House Valves as if anyone can give it a real test and show what it is capable of is Lloyd.
I am 100% sure this will open up many eyes to what the Power House valve can accomplish.
Sure wish I could have continued testing the one I had but with the power it was making it was not neighborhood friendly and caused me all sorts of neighbor issues. BTW I was using a Crosman factory 25 cal chocked (Green Mountain barrel) that is 20.5" long and it is too short to produce the high power that the valve is capable of producing.
The thing that really surprised me on the very 1st shot was the recoil. It felt like I was shooting a PB and from there on I held a much firmer grip on the MRod!
Norm
«
Last Edit: May 27, 2016, 11:50:16 AM by Norm_m
»
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Laconia, NH
N.U.A.H. Club Master Division
Norm
lloyd-ss
Bob and Lloyd
GTA Senior Contributor
Posts: 3567
Real Name: Lloyd
Re: Don Cothran M-Rod Power House Valve
«
Reply #4 on:
May 27, 2016, 12:02:16 PM »
Norm,
Good food for thought. Thank you. The barrel blanks I have are more in the 28" range so I ought to get more of the available power that the valve has to offer. Still won't be neighborhood friendly though.
But I am thinking this will certainly function best as a long range or hunting valve.
Lloyd
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Central Virginia
An engineer by nature. The affliction is knowing that everything can be made better. It is easy to make one that works, but it is difficult to make on that works WELL.
My YouTube channel is Airgun Lab
Iamscotticus
Marksman
Posts: 385
yes
Real Name: Scott
Re: Don Cothran M-Rod Power House Valve
«
Reply #5 on:
May 27, 2016, 12:49:56 PM »
I like the ider of a light strike valve, as I fully intend to use a 1377 rear cocker in my Disco, the hammer may not produce the heavier strikes of the Disco hammer.
so nobody has to ask, yes the lengths from the tube end to the valve stem are the same.
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Texas
Sitting on a park bench.
Eyeing little squirrels with bad intent.
sawtoothscream
GTA Senior Contributor
Posts: 2395
Re: Don Cothran M-Rod Power House Valve
«
Reply #6 on:
May 27, 2016, 02:34:36 PM »
where do you find these? might want to replace my disco valve
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New York
hw97k .177 w/ vortek pg2 sho hawke airmax 3-12x40
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N.U.A.H. Marksman
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Real Name: Randy
Re: Don Cothran M-Rod Power House Valve
«
Reply #7 on:
May 27, 2016, 04:09:58 PM »
http://www.cothranmachine.com/
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Nor-Cal
177. Airmax MK II pistol
22. 1322, pistol/carbine
177. P-rod, double tubed, SS valve, 177. Mrod barrel NSA slugger Plus .22 MM HF barrel
22. Prod, LW barrel, SS valve (House Pest eliminator)
25. Mini-rod, 13cu tank
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357 Slayer
rsterne
Member 2000+fps Club
Bob and Lloyd
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Posts: 26956
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Real Name: Bob
Re: Don Cothran M-Rod Power House Valve
«
Reply #8 on:
May 27, 2016, 04:18:24 PM »
You know I'll be following this with extreme interest, Lloyd.... even though I don't own an MRod.... I would have loved to see you test the Disco version, though....
Bob
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Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
Erockrocket
Plinker
Posts: 143
yes
Real Name: Eric
Re: Don Cothran M-Rod Power House Valve
«
Reply #9 on:
May 27, 2016, 07:15:54 PM »
I am tickled you got your hands on one, Lloyd. I haven't had but a sliver of time to test with mine, hoping to get cracking next week. So far testing has shown an improvement in power to a stock .25 Mrod, but won't show big numbers until its pushing heavy lead. I see a .257 conversion for mine soon, just need to order the barrel.
Keep us posted, hope you make it sing! Eric
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Ohio, Coulmbus
Too many airguns to list, from .177 to .58
StevenG
GTA Senior Contributor
Posts: 2365
yes
Re: Don Cothran M-Rod Power House Valve
«
Reply #10 on:
May 27, 2016, 07:20:42 PM »
That thing looks awesome, but I bet what you do with it is even more impressive.
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West Seneca, NY
lloyd-ss
Bob and Lloyd
GTA Senior Contributor
Posts: 3567
Real Name: Lloyd
Re: Don Cothran M-Rod Power House Valve
«
Reply #11 on:
May 27, 2016, 11:20:01 PM »
Being eager to start, I'm looking over the parts and pieces that I have on hand to find a good starting point. A lot of cannibalized M-Rod pieces, but no matter what, I will have to fabricate something to start the testing. Testing with the stock .25 cal 19.5" long barrel is probably not worth the trouble because it will waste too much air and not demonstrate what the valve will do. Plus, there are already plenty of good options for the stock barrel.
Looking over barrels I have that are already ported for an M-Rod, we've got a .257 barrel, 30" long, and a .308 barrel 22.7" long. All barrel lengths are measured from the muzzle end of the barrel port to the muzzle. I've also got an un-ported .30 cal x 27" long and an un-ported .357 cal x 28" long.
For the .257, I've got cast bullets from 63 gn up to 120 gn. And for the .308, 45gn round balls and 118 and 135 gn cast bullets.
I think the .257 is a difficult caliber for airguns because it usually requires a long barrel and high pressures to get velocities high enough to make good power. But the barrel IS 30" long and there is a wide variety of bullet weights. The .308 is easier to get power out of because of the larger cross sectional area, but the barrel is only 22.7" long and I have a smaller selection of bullets. Both barrels have large ports to make good power.
I am leaning toward starting with the .257 because 1) it is already ported, 2) it is plenty long, 3) a stock .25 cal bolt might work with the .257 barrel, 4) I've got a good selection of bullet weights, 5) it might be an easier conversion for people to make if they were interested.
If anyone can make a good case for starting with a different caliber, I am listening. I know there are plenty of folks who know a lot more about the M-Rod than I do, so I appreciate constructive criticism.
Also, I think I'll start with the lightweight 54gn hammer and see how that does. We'll be working up to a more sophisticated set up, but for now, we'll keep it simple.
Lloyd
«
Last Edit: May 27, 2016, 11:22:21 PM by lloyd-ss
»
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Central Virginia
An engineer by nature. The affliction is knowing that everything can be made better. It is easy to make one that works, but it is difficult to make on that works WELL.
My YouTube channel is Airgun Lab
rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26956
GTA Forums Person of the Year 2017
Real Name: Bob
Re: Don Cothran M-Rod Power House Valve
«
Reply #12 on:
May 27, 2016, 11:25:48 PM »
I think to do the valve justice, you need to test longish barrels, and at least .257 and .357 cals.... You can probably extrapolate the results to get a good idea of what to expect in .308 cal.... If I were you, I would start with the .257, for the reasons you gave, and then jump to the .357 to explore the upper end of the FPE range.... The ports may be a bit small to really make a .357 roar, but the results are important to give MRod owners an idea of what the valve can do flat out.... JMO....
Bob
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Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
Erockrocket
Plinker
Posts: 143
yes
Real Name: Eric
Re: Don Cothran M-Rod Power House Valve
«
Reply #13 on:
May 27, 2016, 11:36:55 PM »
I am leaning leaning towards .357 1st reason, availability of heavy 158 slugs. 2nd reason being the intended use for deer hunting, should it become legal in my homestate. .257 would be fun to stretch out, bit harder to find a range suitable for 200+ yards. May just order both liners at same time.
How long is too long, for a barrel? Is there an ideal twist rate for either caliber?
«
Last Edit: May 27, 2016, 11:42:33 PM by Erockrocket
»
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Ohio, Coulmbus
Too many airguns to list, from .177 to .58
lloyd-ss
Bob and Lloyd
GTA Senior Contributor
Posts: 3567
Real Name: Lloyd
Re: Don Cothran M-Rod Power House Valve
«
Reply #14 on:
May 27, 2016, 11:44:37 PM »
Bob, i agree that spanning the extremes is a good idea.
Eric, as far as twist rate goes, most barrel liners are too fast. Mike Sayers does have an "airgun" .30 cal and .357 cal that aren't on his price sheet and have a slower twist.
Lloyd
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Central Virginia
An engineer by nature. The affliction is knowing that everything can be made better. It is easy to make one that works, but it is difficult to make on that works WELL.
My YouTube channel is Airgun Lab
rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26956
GTA Forums Person of the Year 2017
Real Name: Bob
Re: Don Cothran M-Rod Power House Valve
«
Reply #15 on:
May 27, 2016, 11:56:54 PM »
The TJ barrels in .300 cal and .357 cal for airguns are both 26" twist.... In .308 cal, I think the slowest he has is 20".... There is no "ideal" twist rate, it will depend entirely on how long the longest bullet is that you intend to use.... At the kind of power levels this valve can produce, a barrel being "too long" is something you will not be able to explore, and still have a portable gun.... Barrel flex is another matter, and even at 30", some sort of stiffening may be necessary for the best accuracy....
Bob
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Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
lloyd-ss
Bob and Lloyd
GTA Senior Contributor
Posts: 3567
Real Name: Lloyd
Re: Don Cothran M-Rod Power House Valve
«
Reply #16 on:
May 28, 2016, 12:29:31 AM »
I was noticing that Mike Sayers also has a 40 cal (.400/.408) in 1in 24 twist, and a .44-40 cal (.420/.428) in 1 in 24 twist also. Both of those calibers seem to have cast pistol bullets available, but neither of them seem to be attracting any airgun interest. I wonder why? Just curious. Seems like after the .357, airguns jump all the way to .45 cal.
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Central Virginia
An engineer by nature. The affliction is knowing that everything can be made better. It is easy to make one that works, but it is difficult to make on that works WELL.
My YouTube channel is Airgun Lab
rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26956
GTA Forums Person of the Year 2017
Real Name: Bob
Re: Don Cothran M-Rod Power House Valve
«
Reply #17 on:
May 28, 2016, 12:38:08 AM »
Brent at Extreme has been building and promoting the .40 cal for a while, he uses the .400/.408 barrel shooting heavy rifle bullets at 4500 psi.... No reason the lighter pistol bullets at 3000 psi wouldn't be worth a try.... I have designed some .408 cal BBTs for NOE in 204, 234, and 266 gr.... Even the heaviest should work in a 24" twist.... The 204 gr. FN should be a good choice in a 3000 psi gun.... It is 193 gr. as a HP....
My W.A.G is that with 1/4" ports, .357 cal may be as big as you want to go, to get decent velocity at 3000 psi....
Bob
«
Last Edit: May 28, 2016, 12:40:45 AM by rsterne
»
Logged
Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
MichaelM
BrewMunkey
Expert
Posts: 1099
Xenia,Ohio
Re: Don Cothran M-Rod Power House Valve
«
Reply #18 on:
May 28, 2016, 02:24:52 AM »
I gotta place my vote on the .257 and .357......
I would imagine the lighter .257 bullets would be wicked fast and would stay pretty stable flirting with the sonic barrier...... and then the 357 for brute force...
my feelings are sticking with sub 100 grain rounds in the .257 barrels because once you start getting close to the lighter .357 weights (119gr??) the .357 would be a ton more efficient both air usage and powerwise because of its bigger footprint..... thats my W.A.G. as Bob likes to put it..
though... I would be SO super curious for someone to make a .308 round with a longer profile of say the 147 gr rifle bullet but with a hollow base to keep it around 120-125 grain... I think with its higher F.O.C. weight and shape you could get some impressive B.C out of it for a long range round
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Monkeydad1969
GTA Senior Contributor
Posts: 4347
yes
Real Name: Joe
Re: Don Cothran M-Rod Power House Valve
«
Reply #19 on:
May 28, 2016, 02:28:08 AM »
I have 2 of his Disco/22XX PowerHouse valves in my .25 and .30. The power they generate is sick! I really am going to follow this thread with extreme interest.
Joe
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Colorado---Aurora
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Don Cothran M-Rod Power House Valve