Tuning More power for the FX Maverick

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mtnGhost

mtnGhost

Member
Dec 15, 2018
3,672
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Defected from the PNW, United States
I never really bothered experimenting with the valve on the Maverick until I had a recent failure (my fault for having accidentally dry fired it with a hammer weight and no air when I was doing a modification). Then I realized:

  1. The cocking lever position on the rod is critical to get right, in the sense that if the lever connector isn't attached far enough back that the hammer will slam into the internal cocking rod link in a way that turns the hammer into an SSG-like limiter (and not a very desirable one)
  2. The valve travel is very very limited. Mainly by an interference issue with the valve housing and the valve's polymer sealing poppet and the weak valve return spring (reduces VDT).
    [/LIST=1]

    So as a relatively quick test, I replaced the polymer seal with a PEEK seal that measures about 2mm shorter in length, which I believe prevents it from hitting the housing (I's need to go back in and measure it again. There's another way to modify the valve pin and/or make an entirely different pin that could also work even better, but my Maverick is now pushing the 62gr Varmint Knockers at 998FPS with the 600mm TJ at 174bar. It's a little hammer now and it was bucking my little 6 gallon steel pellet trap (filled to the max with duct seal)!

    I'm also using a 16 gram hammer weight with a heavier ~50-52mm spring, but it doesn't actually recoil as much as my MKII did (shooting them at 950 / 700m with the reg maxed).

    5AAD2E5A-6FA9-4DD2-9457-46A9A35BD7C7.1648783340.jpeg
 
Just ordered a dual transfer port for my .177 Maverick as it just got in stock today.

I am also going to buy the Huma power kit with pin probe - 2 hammer weights and a beefier spring, though i am not entirely sure that is needed, but better that than spending the money on pizza.

Aim is to push 20 grain slugs at 900 FPS maybe 950,,,,,, as a starting point, then i will shimmy my way down in search of sweet spots.

I have also ordered 3 carbon fibre tubes, smallest one have 14 mm id ( same as FX barrel pipe ) and the largest one have the same OD of 28 mm the shroud are, all should fit neatly inside each other for a almighty stiff barrel.

As the Toolman on TV said,,,, MORE POWER !!!!
 
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That's fantastic progress there Gino! And with a 600mm barrel it's even better yet.
Click to expand...

Thanks, Glem! I brought it out to the range the other day to test it out. 10-15mph winds with nothing to use for indicating wind speed and direction. Spent a good 5 hours testing 3 different barrels (500mm .30 Superior 1:37, TJ .30 1:26, and a 600mm Superior Heavy .22).

600mm TJ .30 - had this barrel chambered a little too conservatively, and it was only grouping the 62gr Varmint Knockers around 1.25" - 1.5" CTC (should be MOA or better at 100y). To my surprise though, the 47.2gr NSAs were grouping MOA when I dialed them back to 970 - and those have never done that well for me with any of the 1:26" twist TJs that I've ran.

600mm Heavy .22 was not doing that great at all, but all of my .22 mags are SHALLOW so the largest slugs that I can seat are the 34gr 2-S RBT Griffins. Those shot about 1.25 - 1.5" with random flyers. The XLHP VKs also didn't do as well as I hoped, but the 29gr 2-S RBTs were pretty decent at 1010FPS shooting just over MOA on average.

500mm Superior .30 - I had an upcoming NRL22 match and I ultimately retuned it for 44.75gr JSBs with this seni-rare slow twist liner. Started running out of time, so I wasn't able to shoot pellets over 1000FPS like I had planned. Never really tested this ammo / barrel combo on paper higher velocities, but I was pretty happy when I found a new velocity sweet spot in the low 920's which appears to produce even less wind drift than my previous tunes at 880 and 895!

Tried out some 50.15gr again with this barrel, and about 3 out of 4 went through the same hole with the 4th being a 3-4" flyer LOL! I rarely have the time and patience to sort pellets, but this barrel is very picky about the 50gr head diameters.

I don't have a lot of time right now to compile videos, but here's a couple clips that I poster on IG the other day of the 44.75gr tuned for the low 920's - https://www.instagram.com/p/Cb6SUFJpfdA/
 
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mntGhost,

Just had my Maverick apart this evening replacing my PP O-ring and was pondering new upgrades. Your modification idea is very intriguing. Thank you.

Patrick
Click to expand...

Yeah, it's a fairly low tech solution that mainly benefits longer barrels. More like a stop gap solution. I have some better ideas on how to increase and control the poppet travel, but I just don't have the time to fabricate all of the parts needed :(
 
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mtnGhost said:
I never really bothered experimenting with the valve on the Maverick until I had a recent failure (my fault for having accidentally dry fired it with a hammer weight and no air when I was doing a modification). Then I realized:

  1. The cocking lever position on the rod is critical to get right, in the sense that if the lever connector isn't attached far enough back that the hammer will slam into the internal cocking rod link in a way that turns the hammer into an SSG-like limiter (and not a very desirable one)
  2. The valve travel is very very limited. Mainly by an interference issue with the valve housing and the valve's polymer sealing poppet and the weak valve return spring (reduces VDT).
    [/LIST=1]

    So as a relatively quick test, I replaced the polymer seal with a PEEK seal that measures about 2mm shorter in length, which I believe prevents it from hitting the housing (I's need to go back in and measure it again. There's another way to modify the valve pin and/or make an entirely different pin that could also work even better, but my Maverick is now pushing the 62gr Varmint Knockers at 998FPS with the 600mm TJ at 174bar. It's a little hammer now and it was bucking my little 6 gallon steel pellet trap (filled to the max with duct seal)!

    I'm also using a 16 gram hammer weight with a heavier ~50-52mm spring, but it doesn't actually recoil as much as my MKII did (shooting them at 950 / 700m with the reg maxed).

    View attachment 202021
Click to expand...
Hi man ghost , I have had a similar problem , not realising the gun was still cocked I fired the gun without any air in the gun and now it leaks air out of the barrel , I am unsure how to fix this , did you replace the valve spring , I inspected the valve and there seems to be no damage , it is a fast leak , thanks Andy
 
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andysodyssey said:
Hi man ghost , I have had a similar problem , not realising the gun was still cocked I fired the gun without any air in the gun and now it leaks air out of the barrel , I am unsure how to fix this , did you replace the valve spring , I inspected the valve and there seems to be no damage , it is a fast leak , thanks Andy
Click to expand...
Your valve is probably broken somewhere. If it didn't break, then all you can do is cock the rifle to ensure there's no pressure on the valve (or remove the hammer spring), and (at your own risk) plug the barrel so it will force the valve to shut as you reattach the bottle.
 
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