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Benjamin marauder pressure ?

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bobby

bobby

Member
Apr 19, 2015
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I have been lucky enough to get a 25 cal benjamin marauder for pretty cheap and I was thinking about turning it into bottle rod , regulated and lothar walther barrel or smooth twist not sure just yet but I really would like to know if I use regulator could I fill the gun to 250 bar I think so but I would like some other opinions I believe the the only reason you can't fill it to 250 bar stock is because of the valve if anyone has any ideas I would like to hear them thanks
 
I am thinking of a Huma regulator with the pressure gauge then the bottle drop down fitting to monitor the tank pressure I believe that the 30 cal would be a blast to build I have a long winter ahead of me and need something to do I do construction so get the chance to meet a lot of people who can help me out with the machining part and I would just order a stock maybe from boyds or make my own bullpup stock just a thought I think the 250 bar fill would be great for the shot count
 
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The stock airtube is 3000psi max and that is if it is regulated or not. If you have it bottled and regged at the bottle, then you can fill to whatever the bottle is rated for. If you run a bottle, but reg the remaining airtube then 3000psi is still your max fill pressure.

If you want to stay .25, as good as many of the stock GM barrels are, I would not change it. If for some reason your GM barrel is not up to par, I would skip a LW for sure and even a ST and go for a TJ'S barrel instead. Just my .5 cents worth.
 
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Good post, I have a 25 marauder that I call a 10, It shoots right with my 22 and 25 Crickets at 100 yards, I got about 400 dollar worth of after market parts with it , slings, air extensions, trigger jobs, suppressors, Tripods, scope and rings, I might get 550 out of all of this stuff, But this gun shoots right with my 2,400 dollar crickets,
I think I want a bull pup kit for it, a bottle kit for it, and a super tune wicked air, This thing just might out shoot my Crickets...
Really I am not sure, One hole is one hole, How can you out shoot that....
I really like my marauder and its performance, but I am a bull pup fan,
I just can not see selling a gun of this caliber for 500 bucks. ( crazy)
Looks like I am going to be spending some money down a dark hole,
Sure the shot count is not up to the Crickets . But I got my own compressor,
and one hole is one hole no matter what gun you are shooting...
It knocks a hole in my Vulcan purchase, But hell I do not think a new Vulcan will out shoot my .25 Marauder.
Just the facts jack....
Black hole here I come,, LOL
Mike 

 
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I hear that l know that I will be spending another 1000 bucks to make it what I want but like I said I have nothing but time and if I get it right maybe just maybe I could take it to extreme bench rest just need to to get this 250 bar fill solved and I think i can figure out the rest as far as accuracy. lothar walther barrel ar very much accurate but maybe the smooth twist barrel is just a little bit better at longer ranges thanks for the input guys
 
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 Maybe I am reading this wrong,
"I planed to have the tube cut and re threaded right before the pressure gauge / regulator"
But if I'm reading it right it does NOT sound safe.
To be safe the reg. needs to be in the bottle ( and you could shop around and accomplish this) , IF the reg. is in the - cut - tube the portion of factory tube that is left will be seeing 250bar and that is not safe. Perhaps even less safe after being cut & such?

Do not feed anything over 3,000psi to any of the factory parts , tube, valve, threads, .... , .


John
 
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Cutting the tube down and rethread does not make it "weak". It is the simple fact that the only way to go above 3000psi is to have a regulator on the bottle so that the pressure in the remaining airtube never goes above 3000psi.

If you were to use a carbon bottle and fill to 3600psi without a reg on the bottle, then the airtube containing the valve, and regulator is going to be subjected to 3600psi which is dangerous because the airtube is only rated for 3000psi no matter what.

The only way to use a marauder with fill pressures way above the rating is by using a regulated bottle. This keeps the high pressure on the bottle side and only allows your set reg pressure in the tube. That pressure will be less than 3000psi and that is fine.
 
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pcptunesMy 2 cents, even if you have a regulator, all parts must be rated to 1.5 times the max air pressure you intend to use it for (in this case the airtube containing the valve) is your weak point. You got to take into consideration the failure point of the regulator as well.
Click to expand...


The mrod tube including valve, anchor screws, fill assembly, etc is rated at 3000psi with a 3 to 1 safety factor. If I understand, you would feel safe filling a stock mrod to 4500psi?
I don't intend to create an argument, but have always been led to believe that a safety factor of 2 is the lowest anyone should go. Do you have data to prove 1.5 is safe?
 
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I was not arguing for using unsafe pressures, but could you explain further?

I believe the OP wants to build a gun with a 3600psi max fill. The tube is rated max fill of 3000psi with a burst or safety factor of 3. If a regulated bottle is used that could be filled to a max of 3600psi, but regulated output below 3000psi so that the tube will never see anything above 3000psi. This is unsafe?

I don't have any guns of this nature, but I know people are selling mrod modes to do exactly what the OP is looking for. I am just curious if this is unsafe? I have no skin in the game, just curious.

Maybe I am misunderstanding you? 1.5 times working pressure for an mrod tube would be 4500psi and a 3600psi regged bottle is well below 4500psi.
 
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When we tune or make kits for airguns we ensure all components can withstand the max pressure you intend to use your airgun.You point is valid about the regulated output to the tubes working pressure, but we need to look at the regulator failing completely and allowing that 3600 psi to get through to the tube.I do understand that if crosman follows a safety factor of 3:1, nothing might happen even if the reg fails and 3600 psi was to get to the tube. But they have rated it to 3000 psi for the same safety reasons and by upgrading the mrod to be used at 3600 psi we are breeching that. But as we are recommending the mod, its correct to machine to 1.5 times the max working pressure you intend to fill irrespective of the regulated output. More the better :)
And about people selling stuff , I would not want to comment on that.
And yes a bottle rated to 250 bar can handle 4500 psi, but that does not mean we fill above 250bar.
That's when airgun companies install burst disks to cut off that excess pressure (above the rated pressure of the bottle). For safety
Good Day !!!
 
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The advice on overpressure is good and you should listen closely. My advice is to go ahead and cut the tube to the length you were proposing, regulate your bottle to a pressure that gives the caliber you have chosen its best consistency in shot deviation. As an example say a bottle pressure of 3500 or higher psi regulated to say 2200 psi if that is your most consistent shooting pressure to achieve your desired feet per second for the caliber and pellet or bullet weight. I shoot my 25 caliber Marauder most consistently at between 2600 psi down to 2200 psi using the JSB in about 25 grain weight at 887 fps average unregulated. The JSB Heavies at the same pressures yield a speed of 794 fps average but are a bit better in accuracy further downrange. What I give up in feet per second I gain back in foot pounds of energy on target at the higher yardage. I can not speak for the 30 caliber although I have been tempted to go for a rifle in that caliber. For my shooting the 25 caliber does what I need both in hunting, accuracy and noise (suppressed). I jumped to 45 caliber and low shot count when the game increased in size and just put up with the crack of the rifle in the field for hunting.
Hey the Marauder is a great platform for tuning and modification. Good luck if you decide to move forward with the project and keep up the chatter as you progress.
 
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