Regulated .177 M-rod build about to get started.

Forums PCP Airguns Regulated .177 M-rod build about to get started.

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    ajshoots
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    Since Archer Airguns had a run of refurb M-rods, I jumped on a gen2 .177 with wood stock. I have a Huma reg from Nick at Air Superiority Products on the way and a few other items I have in my parts bin to throw at this gun. I also plan to machine a hammer out of nylon as well as some other mods that should make for a great regulated M-rod. I am willing to buy a quality blank as Crosman can produce a good .177 barrel, but I am not counting on it. The plan is a 12fpe gun, but will wait to see how the build progresses. If the barrel is good, I will let it dictate what weight pellet and speed I will tune for. I hope 12fpe works out as the shot count will be huge and I love doping the wind with 12fpe at 100 yards!! Reminds me of a 1000 yard shot with a high horsepower centerfire!!

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    Dan25
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    Cool, your Mrod condition deepens.  You are so far past a 12 step program it just aint funny.  Keep us updated on the groups and shot count.  I am strictly a hunter and pester so I tend toward the larger rounds but spent a wonderful childhood with the 177 bore.  So many fond memories of stalking close enough with my trusty Benjie smooth bore.  Its 45 years old and I still have it.

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    ajshoots
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    I said I would never own another .177 because all I do is hunt and pest as well. But, a .177 will give me all 3 mrod calibers, plus my .30 mrod and my prod. A full collection LOL!! Luckily I have been very busy blueprinting and tuning mrods and prods for people, so that is helping fund my disease!!

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    ajshoots
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    I have had the gun since Saturday and while waiting on the regulator I got the gun all ready to drop the reg in. Worked on the trigger and set it to my typical single stage breaking at 9oz. Did all the deburring and polishing as well as the needed modifications to the valve, barrel, and TP. The regulator arrived yesterday. I had already decided to delete the gauge, so I put the reg in and reassembled the airtube. Filled it up to 3000psi and put everything back together. The only .177’s are my kids guns, so all I currently have are 7.9boxed premiers. I loaded up 3 clips and started shooting over the chronograph. The first shot went 1050fps. Not what I was wanting as I had planned for a lower power high shot count. The reg was set at 1900psi which I figured was too high,but I had also done alot of internal work, so I wasn’t really sure what was causing the high velocity? I quick call to the Huma expert(Nick @ Air Superiority Products) and he gave me some ideas to try. I have since torn the gun down 3 times trying all sorts of combinations of valve springs, hammers, hammer springs, and TP’s. Right now I am at 60shots 967fps avg 25ES and 4SD. Next step will be to try a different valve. As I continued working on the gun, I kinda set a goal of 900fps for the 7.9gr CPL’s, but I am struggling to get the speed down with the current valve.

    This gun is actually going to be a Christmas present for my wife. We used to do alot of powder burner shooting together and hunting as well. It is difficult to get out hunting and shooting together since having or first child. Now with 2 and the 3rd and final due in March, it is getting much harder to say the least. We did do alot of airgun shooting with the kids this summer and she really enjoyed it. The kids have their own airguns, so it is only fitting that she gets her own as well!! I ordered a scope and rings last night. http://www.midwayusa.com/product/962234/bsa-tactical-mil-dot-rifle-scope-30mm-tube-6-24x-44mm-side-focus-glass-etched-mil-dot-reticle-matte

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    spysir
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     I’ve only installed 1 .177 marauder regulator, purchased from Vincent when he first got them ( not sure what name brand reg that would be). Just dropping it in the tube – rifle had been set close to 20fpe prior to install-  reg was stated to have been set at 130bar and with only dropping the reg in and shooting it got 64 shots at aprox 885fps with 10.3g with an extreme spread of 18fps.
     Great rig for FT and just fine for hunting at 50 yards or so.

     Now 12fpe at 100, ya buddy. In my case 12fpe at 110 yards – just worked out as where the backstop would fit- IS a good time esp with some swirling winds.

    Keep us posted.

    JOhn

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    ajshoots
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    John, I was really wanting to go 12fpe as I agree that doping the wind at 100 with 12fpe is alot of fun!! I am a bit baffled why I can’t get the speed down? I have a stock hammer that I shaved 20grams of weight off and I just put it back in trying to get the velocity down. The gun actually picked up a few fps and the ES and SD tightened up. I am more than happy with the shot count, but really want to drop the velocity alot more. This is my first attempt regulating a M-rod and my only other experience with regulating was 2 P-rods. I have alot to learn yet!!

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    ajshoots
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    Well, I made a 20gram hammer tonight out of MDS Nylon. Stock hammer 78grams and one I lightened to 57grams gave me nearly the same results around 970fps. I installed my 20gram hammer and velocity fell down to 750fps!! I was able to get the velocity nearly anywhere I wanted by increasing hammer spring preload. I didn’t leave much clearance for the hammer to clear the sear and reset. I finally ran into an issue of the gun not resetting the sear do to the length from cocking pin to the front of the hammer was alittle too long. This caused a double load. I cleared the pellets with a cleaning rod. I had to chuck the hammer back in the lathe a take some material off the face to allow for proper cocking and sear engagment. I reassembled and the velocity was all over the place. I think I may have damaged the breech seal when I cleared the double load. That, or the hammer is not striking consistently? Unfortunately I am waiting on an order of orings that has my .177 breech orings in it. Hope they show up tomorrow so I can diagnose the problem. I really hope that is the issue and not the hammer. Was really happy to be able to get down to 12fpe!!

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    Bruce.net
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    I am hoping to regulate my refurb Marauder over the winter.  I already have the light-weight hammer, but I have to order the regulator.

    The one thing I keep reading on some of the other forums is the need for a lighter poppet valve spring with the lighter hammer.

    Can you provide any more detail on the valve mods you have done to date?

    Good luck.

    Bruce

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    blackdiesel
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    It’s always great to see what you expert tuners can get out PCPs.  Rafael who did my 30 cal tuned a 22 M-rod to get 44 regulated shots @ 900 fps with 18 gr JSB pellets.  

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    ajshoots
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    Bruce.netI am hoping to regulate my refurb Marauder over the winter.  I already have the light-weight hammer, but I have to order the regulator.

    The one thing I keep reading on some of the other forums is the need for a lighter poppet valve spring with the lighter hammer.

    Can you provide any more detail on the valve mods you have done to date?

    Good luck.

    Bruce

    I opened the exhaust port to .160 and the throat I went up 1 drill size from stock, but can’t remember what size that was. I also increased some volume in the valve body and cap. I have been playing with different valve springs as well, but just haven’t gotten the right combination yet.

    I did confirm that my new hammer is the issue and not the breech oring. I am going to make some different hammers tonight after work and see if that helps. I think I made the first hammer too small an OD and that is allowing the hammer to cock sideways. I think that is my issue but will be testing that theory this weekend.

    Wanted to make sure that I didn’t have any others issues, so I put a polished stock hammer back in and was able to get 60 shots at 966fps with an ES of 17. Using 7.9 boxed premiers. That proved that I just need to sort out my lightweight hammer issues.

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    John_in_Ma
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    In reading your previous posts I know you like power out of your mrods and such.  When setting one up for 12fpe opening up transfer ports and valves and such is the opposite of what you should do.  When I had mine I was tinkering with 12fpe settings.  I had the transfer port screw just 1.5 turns out from closed, hammer spring 2.5 turns in from backed out all the way, and striker length 1 3/4 turns in from all the way backed out.  I was getting 45 shots with very similar ES a SD using 8.4 grain pellets from 2800-1800 psi.  If I had kept it and regged it  I would have expected to double my shot count and tighten up the ES and SD.  Anyways good luck with your project and Merry Christmas.  John

    Edit:  My average fps was 780

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    ajshoots
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    Opening up valve flow was recommended by others that reg guns as free flowing valves work better with regulators is what I was told. My first instinct was to keep everything small. Actually a stock valve wasn’t as efficient. Already tried that. Setting up a regged gun is new to me, so I am trying all sorts of things to see what affects what. I think the efficiency will be better with a heavier pellet also. 7.9’s are all I currently have.

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    ajshoots
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    60 shots at 16.5fpe with a 1%ES. I can live with that. I still don’t have the lightweight hammer light valve spring combo figured out yet?? Motorhead has it perfected, but I am still struggling. I can get the power down to 12fpe and get 100shots, but can’t get the ES down.

    I am enjoying the learning curve, so that’s all that really matters. I have the concept in my head, just need to get a few more things figured out and I think I will have a happy 12fpe gun.

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    30cal
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    Opening up the ports does seem counter intuitive but I’m no expert on regulated guns either. All I know is that to get 39 fpe out of my regulated .22 I had to open the TP and barrel to .160″ along with a Hill valve. Also the Hill valve does not have the restricter screw in the exhaust port which makes for a smoother flow but maybe less adjustment. Anyway good luck in your quest. Sounds like a fun project. I’m still waiting for my MM barrel btw. 

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    ajshoots
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    The point of opening up the valve is intended to be used with a lightweight hammer and lighter valve spring. This work has been proven by Motorhead, but I am unsure of exactly what he does, so this is an experiment for me at this point in time. What I did to the valve has been all trial and error. If I end up using the stock hammer, I will have to go back to a stock valve to get to lower power levels. The valve flows so good, that with a stock hammer, the gun doesn’t respond to striker or hammer spring adjustments or changing TP size. The only way to slow the gun down and increase shot count is reg set point. By simply dropping in the light hammer, the gun is fully adjustable from 10fpe on up. I just can’t figure out if the hammer is not striking consistantly or i don’t have the right valve spring in as the ES is all over the place. Yes, I could go back to a stock valve and get down to 12fpe, but the efficiency gains that have been proven with the light hammer setup is what I am chasing.

     

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    30cal
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    You may have to go back to a metal hammer to get the consistency back. I think nylon may be a bit sticky compared to steel and may be causing the inconsistency. Also plastic and steel have different expansion rates and that can cause the hammer to be tighter or looser depending on temp. Just some thoughts as I’m sitting in front of the computer having coffee thinking about your project on this cold wet Saturday morning.

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    ajshoots
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    The mds nylon is a very slick material and is not sticky by any means. I need to balance the valve spring to the hammer weight is one issue and I am alittle off on my hammer size. I should have made the OD bigger for a more precise fit. A number of tuners have been using delrin and nylon hammers for awhile now. I am just behind the learning curve.

    I did make a few changes with a steel hammer and was at 925fps avg with an ES of 5fps. I didn’t have time to run a full string to see total shot count, but thought that was good for the 40 shots I ran over the chrony. Will run a full string when I get home.

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    ajshoots
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    I have torn this gun down so many times that the heads started breaking off the breech screws!! I have lost track of how many times I have completely stripped the gun down, tried different combinations of parts, and how many different hammers I made and how many stock hammers I modified. For those that have read any of my posts, like John_in_Ma said above, I usually build unregulated marauders and power is the goal. This regulated .177 has been a great learning experience. In order to get to a large shot count low ES low power tune, I need the pellets and springs I have ordered. Unfortunately, I won’t receive any of these needed items till after Christmas. For now, it will be 16fpe, 60 regulated shots @ 1%ES. Also looks like the scope and rings will not make it before Christmas either. I wanted to give this gun to my wife Christmas morning ready to shoot. Not gonna happen. But, Wednesday is my last day of work till January 4th, so I will have plenty of time to get it dialed in for her.

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    ajshoots
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    Thankfully the scope and rings showed up today!! I got the scope leveled and mounted, but it is really windy today. I did get it close at 30 yards, but with 20 mph gusting winds, it is impossible to get it spot on. Atleast it is ready for Christmas morning. Hope my wife likes it.

    Even with the windy conditions, I am rather suprised how good it actually shoots 7.9’s at 970fps. Had a brief period were winds held steady and put 7 in the same hole at 30 yards before it started gusting again.

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    Lanky94
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    I am about to regulate a custom .177 discovery based gun to sub 12 ft/lbs. From limited previous experience, I open everything up for max flow, including the valve volume. I port match everything- starting with the barrel port at 75% of the bore. I work it back from there- barrel port, transfer port, valve exhaust and finally throat ( minus stem diameter). I set my reg at the lowest setpoint possible to achieve power. tune gun with power adjuster by using a light striker with a long throw. 

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