Friend's regulated .22 Mrod & getting more shots

[Doug-T]

Yesterday a friend brought over his gen 1 .22 Mrod and a new HUMA .25 regulator with gauge port. We installed the regulator, drilled out the transfer port/barrel port/valve port to 0.155" and tuned it to shoot JSB 18.1g at 895fps with the regulator set at 2000#. From a 3200# fill down until the regulator set pressure it gets about 30 very consistent shots then once off regulation it rises a bit then falls off pretty quickly. He'd like to get more shots per fill. He'd like to keep this budget friendly so buying expensive aftermarket valves, hammers, etc isn't really an option. I have a lathe & mill in my garage so building things isn't a problem. Here's what I'm thinking. Any input would be appreciated.

-Lowering the regulator pressure to 1800#.

-Machining a 40-45 gram nylon hammer. I have a stick of 1.25" MDS that should be perfect for this.

-Building a captured hammer spring of some sort to prevent hammer bounce. I'd like to know which DIY is the most effective. I can machine whatever is needed.

-Bore out the end of the valve body to allow more regulated air inside the valve body. Recommended boring diameter & depth? 

-Installing a lighter valve spring.

-Possibly installing a larger transfer port than 0.155". What are the best options here? 

Is there anything else?

Thanks.

Doug

 

[Motorhead]

In .22 cal and those porting specs ... IMO your still going to require 1800-2000 psi. A Lighter hammer no more than 30 grams if using a conventional hammer spring set up and likely a bit more if using an *SSG ( * highly recommended ) A softer poppet spring too !



Honestly at that current power level getting 30 good shots on 190'sh CC's of air is pretty good. You may find 5-8 more with some better efficiency tuning, but that is going to take some effort. Want more shots / back off on the power to the 850/860 range.



YES, modified valve being bore out ( Gen 2 ) or sleeve removed ( Gen 1 ) .... throat at .250" and an opened up end cap & conical poppet spring to allow max flow from plenum into the valve. Transfer path of .165" has to be Valve to Barrel being all at the same specs.



JMO tho ...



Years ago when I was doing the R&D on the Marauder LW hammers and regulators my Ideal tune on .22's came with a Reg setting at @ 130 bar, LW hammer at 26 grams, soft poppet spring, OEM hammer spring on .165" ports. Set to shoot JSB 18.1's @ 865 fps would do 40 shots on reg and still give 10 more off reg all with an ES of 10/12 fps.

Set up as such ... 50 shots on a 3k fill ... No Lie !



Scott S

 

[Doug-T]

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[Doug-T]

Scott,



Thanks for the great info. 50 shots is awesome! Wade would love to tune his Mrod down to 1800#. If this goes well I'll be doing the same thing to my .22 Synrod. I hope you don't mind me asking a few questions. 

-What SSG would you recommend? 

-Would the Hill #6 valve spring be a good option?

-What are options for a 0.165" transfer port? II needed I can machine an aluminum or brass one and get small O-rings.

Thanks.

Doug

 

[Motorhead]

Scott,



Thanks for the great info. 50 shots is awesome! Wade would love to tune his Mrod down to 1800#. If this goes well I'll be doing the same thing to my .22 Synrod. I hope you don't mind me asking a few questions. 

-What SSG would you recommend? 

-Would the Hill #6 valve spring be a good option?

-What are options for a 0.165" transfer port? II needed I can machine an aluminum or brass one and get small O-rings.

Thanks.

Doug

SSG devise, make my own with is a self contained unit NO PASSING THREW HAMMER. The end of screw in outside the end cap and when action is cocked it protrudes out the back doubling as a cocked indicator. This type SSG & it's mass/ weight stays independant of the hammer weight and & mass. So as hammer is thrown at the valve is FAST, and drag free being far more accurate in delivered strike energy than any other style. Tho ... a Threw hammer design does work better than no ssg at all ... FYI

No ideas on HILL parts ? .... If sold as a light spring to be used in Regulated guns I'm sure it is fine. Tho if it allows a bigger intake hole in to the valve NO CLUE ?

165" transfer done via a Delrin / Acetal tube machined to be a tad longer and put under light compression as receiver gets screwed down

 

[Saltlake58]

just tuned my Mrod with a new regulator. Currently getting about 50 shots per fill at 830fps with 14 grain pellets. JSP 18 grain shoots at about 760 fps, but highly accurate at 50 yards. Key was installing 3 parts from Hill - Lighter hammer spring, lighter valve spring, and the HFTP Transfer port (plastic tube that gives full air flow). Springs and HFTP were under $30 total, well worth it to ensure consistent airflow. 

Regulator is set at about 1650 PSI, Hammer spring Zero, Hammer Throw, Zero, Transfer Port open 5 full turns.

You can tune a Mrod to be more powerful, or in my case, for more shots. You can also spend enough on Hill parts to buy another gun. Be careful!

If I do anything else to the gun, it'll be the Hill light weight hammer, but that's expensive, so for now I'll be satisfied with 50 shots. I've heard of people getting 80 shots, but that requires the Hill hammer, and I don't want to spend the $$ right now.

 

[Doug-T]

Thanks for all of the info.

 

[Doug-T]

Today I took Wade's Mrod apart and made the following changes:

-Lowered the regulator pressure from 145 BAR to 125 BAR (1812 psi)

-Installed a Hill #6 valve spring. Much lighter that stock.

-Installed a 42 gram nylon hammer that I built.

-Installed a captured hammer spring (10-24 bolt, nylon bushing, 2 washers, thin nylon insert lock nut) as long as it would go without contacting the valve stem (2.24" in length).



Today I shot the first 30 shots of a string then had to go to a wedding so I finished the string as daylight was leaving. The red circles are chrono errors. 3200# fill pressure. JSB 18.1g. I calculate an air reservoir volume of 202cc. How does this look? i'd like to see a bit less peakiness (872 & 849). Towards the end of the string I was connecting the Hill hand pump and pumping it up until the fill valve clicked then noting the pressure. The Hill gauge seems to be the most accurate one we have. The captured hammer spring bolt threads may be catching on the washer that it slides through. i'd like to find a source for 10-24 Allen head bolts that are 2.5" long with a smooth shaft below the head.

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[Motorhead]

There ya go ... A tad higher pressure on reg ... so when it comes off REG at a slightly higher pressure hammer strike energy will cause the string to be flatter or ideally rise @ 10 fps as you come off the reg and then slowly fall away & not fall hard like it is doing now past #38



42 grams of hammer weight is still MORE than required IMO. Hope I'm not breaking any cross forum rules ? but here is the Original R&D thread on the use of LW hammers in regulated Marauders ... https://www.gatewaytoairguns.org/GTA/index.php?topic=38088.msg405917#msg405917

Make note of POST #4 & this was near 7 years ago ! and prior to SSG or TSS hammer spring devises.

Your very close !



More good stuff here ; https://www.gatewaytoairguns.org/GTA/index.php?topic=38165.msg355273#msg355273



Scott S



PS ...

Another notable trend is that the gun shows it LOVES @ 1800 psi or a tad lower with the available hammer strike running about 850 fps. Another way to optimize the shot count at a slightly lower power is setting the Reg at > 1.8k where the string would be super flat and when you come off the reg your cruising along self regulating as you seeing now from @ #40 onward. Tho if you want the higher power output, will need to stay at a higher set point.

 

[Saltlake58]

I just installed a regulator, the Hill 20 gram hammer, striker combo, the 262 spring, the Hill HFTP transfer port, lighter valve spring and set the reg about 1800 to 1900. Hard to tell on the Crosman gauge.

Up to 65 shots per fill, and sends a JSB .22 15.89 pellet at 840 fps. Weighed and unsorted pellets range from 838 to 842fps. In windy conditions, 7/8 inch groups at 50 yards tonight. Most of the deviation was the shooter, not the gun. Marauder Gen II about 6 or 7 years old. 24.9 fpe.

I had another combination of parts going, that was nearly as efficient. It was a regulator set at about 1800 psi, the Hill 255 spring, lighter valve spring, HFTP and the factory hammer. The 255 is lighter than the 262 and combined with the factory hammer, still gave about 840fps for the 15.89's and shot about the same groups. The hammer / striker from Hill was around $70, so could have saved the $70 but would lose 10 shots per fill as that combination gave 55 shots per fill. This combination also has a much lighter cocking pull.

I've been working on this for several months working out the combination of parts that is most efficient. So, here's what I spent:

Hill 262 spring $10, Audrius Regulator $70, Hill Hammer and striker $70, HFTP $6, lighter valve spring (Hill also) $10, so under $170 for all the parts. If you go with the factory hammer and 255 spring, that'll save $60 or so.

Highly recommend the second combination, and the first if you really want total efficiency. Really nice to shoot 6 magazines before reloading.

Settings are Hammer Spring 0, Hammer throw 0, and transfer port at +6. Open the transfer port wide open. That gives 840 fps and really reliable and accurate shooting.

I also recommend polishing the inside of the air tube where all the punchouts are. To accomplish that (because I'm cheap), I took the center section of a cleaning rod, wrapped some duct tape around it till it was 3/4 inch thick, taped some 300 grit sand paper to it and spun it with a drill. Then went to 4oo grit, 600 grit, 1000 grit and 1200 grit. Smooth as glass in there now, and no burrs to rip O-rings apart.

Good luck!

 

[Doug-T]

Thanks for the info Motorhead and SaltLake 58.

It looks like this project cost about $134. Pretty budget friendly. HUMA regulator ($120), Hill #6 valve spring ($10), captured hammer spring bolts/nuts ($3), Nylon for hammer ($1), misc steel I already had laying around.