Tuning Marauder FT regulator removal, tear down

[SqrlHntr]

Tearing down another m-rod, this time a FT model. Found a few things I’d though I’d share, good and bad. 


FT model in .177 shoots 10.3gr FX @ 885-890fps, factory tune. HS was 6, HT was almost all the way out, 11 turns. Crosman made a vent hole between the valve and the gauge port. Pic shows Huma m-rod reg, Crosman factory reg and a Huma XL plenum. Huma now makes a drop in to fit the FT, but the XL plemum will span the gauge port hole like any other m-rod. Measurements were made from the inside edges of the holes, vent is smack in the middle. Couple of sour notes though, metal flakes and crumbly aluminum dust were in the regulator, suprised it has not dislodged and clogged up a stem. Could be what caused another user’s post about a bad regulator (?) Barrel was scratched to hell at the breech, and the baffles must be glued in the shroud in the FT model, my .22 FT has lodged baffles too. Other posts already about the baffles. Crosman support has no clue, told me they should fall out. Barrel shoots really well without touching it, so im not gonna complain much about scratches. Wont matter by tomorrow, adding a Huma reg w XL plenum, Hill regulated parts kit w 255 HS, 7 VS and PEEK striker, Barrel polish and h-BN treatment, SS screw kit, and replacement shroud w/o baffles. 

 

[2L8]

Excellent post SqrlHntr.

Patrick. 

 

[SqrlHntr]

Excellent post SqrlHntr.

Patrick.

Thanks! One note I forgot to add is that some the grey aluminum dust was past the plastic nut in the regulator, the pic shows the nut removed to see the dust better but there was in fact some past the nut. The stock screw was roughly drilled out too, had some sawdust on the trigger housing. 

Despite the QC issue, which I expect is really just a one off for Crosman, this is a shooter for sure. Not the first manufacturer to experience a QC problem as of late either. It stood out because with any of my m-rods, p-rods, 1701’s or 22xx’s, (and thats a double digit in total) not one issue out of the box. Not even a leak or a loose screw. Dont want people to think im bashing Crosman, quite the opposite. I love the Marauder platform and Crosman is known for superior support and service, no doubt they would take care of it asap if i needed. The Mrod FT an excellent rifle for FT out of the box, this one just hit a snag on the assembly line. Still would recommend, has not changed my love for Mrods in the least.

 

[rong1966]

Great post. I may be the poster that you are alluding to with the bad regulator. The internal o-ring was deformed/worn. What is your goal with the extended plenum and other upgrades?

 

[TiredRooster]

This is an interesting post. I have a .22 Marauder FT model and my baffles will easily just fall out. They are definitely not glued or adhered within the shroud in any way. 

 

[SqrlHntr]

Great post. I may be the poster that you are alluding to with the bad regulator. The internal o-ring was deformed/worn. What is your goal with the extended plenum and other upgrades?

Thanks for reminding me as to the cause. All I remembered someone had an issue. Hope you had it fixed.

The FT model really doesn’t need all the aftermarket parts to be competitive IMO. The thing shoots amazingly well out of the box I really shouldn't even touch it. To answer about the parts, let me start with this. There are plenty of people here who are way more versed with modding M-rods, I just do what works for me and what I know how to do and yes, modding mrods is a few years late in the evolution of airguns. I started modding mrods and p-rods with Hill parts as a suggestion to me and never really considered an alternative besides Cothran valves. Using Tim’s parts as a start, an ES close or better than 1 is achievable on a Marauder. I know theres other ways and methods, such asspending thr $ on a higer end gun, but his stuff works really well for me. The XL plenum was a spare for a .25 m-rod. Huge plenum for .177, I know, figured I’d see what I could do with it. With a Huma tester the reg set point can be really dialed in for fine tuning. The h-bn barrel coating process is something Ive been testing, uses an h-bn barrel coating solution and pellets tumbled with h-bn for break in, setting the fractured nanocrystals into the steel molecules. 

 

[SqrlHntr]

This is an interesting post. I have a .22 Marauder FT model and my baffles will easily just fall out. They are definitely not glued or adhered within the shroud in any way.

That is interesting. Mine were both lodged and broke when trying to remove. When did you purchase yours? mine were both recently, past few months. Wondering of they are out of round, a qc issue maybe. Another forum had a comment about the baffles being stuck.

 

[FuzzyGrub]

Thanks for the details on this. I don't have a F&T, but have a SAM that uses a similar air tube and reg. I am looking at options to bridge the vent and make the plenum larger.

I don't have the XL plenum. Could you answer a couple questions on it?

- Does it have surface O-rings that seal against the face on both ends?

- What is its length and ID?

- Does the crosman reg fit in the end such that it will seal against the middle section?



The too tight baffles has recently come up on another forum. It sounds like a bad batch of baffles.

Never seen those kind of scratches on a Mrod barrel. Some kind of burr in the breech? Set-screws not out far enough when installing?

Crosman put a fix on the regs to keep the adjustment from moving. A side hole with some form of locktite. This may be one that was fixed internally, before new built regs arrived. ie aluminum chips.

 

[SqrlHntr]

 

Thanks for the details on this. I don't have a F&T, but have a SAM that uses a similar air tube and reg. I am looking at options to bridge the vent and make the plenum larger.

I don't have the XL plenum. Could you answer a couple questions on it?

- Does it have surface O-rings that seal against the face on both ends?

- What is its length and ID?

- Does the crosman reg fit in the end such that it will seal against the middle section?



The too tight baffles has recently come up on another forum. It sounds like a bad batch of baffles.

Never seen those kind of scratches on a Mrod barrel. Some kind of burr in the breech?

Crosman put a fix on the regs to keep the adjustment from moving. A side hole with some form of locktite. This may be one that was fixed internally, before new built regs arrived. ie aluminum chips.

XL plenum is for the Huma regulator, removing the Crosman reg and gauge port altogether. There is one o-ring that seats against the valve and it does span the gap of both vent and gauge port. I checked the breech and no burrs to scratch the barrel. What I cant figure out, maybe someone can explain it, is how the factory regulator works. Seems more like a constrictor than a regulator. Factory tune of 6 hs 11 ht made me scratch my head some. Apologies for the upside down pic.

 

[FuzzyGrub]

Thanks for the info and going overboard and taking the time with the pictures.

Only fitting the Huma on the one end is what I thought, but was hoping it was more like the Huma plenum in prod/discos/max.

While the easy route as far as fitting, I could go with Huma. I am concerned its slow fill won't work well on the SAM. Thanks again.





You will definitely have big enough plenum for a 177.  Not sure of the power level you are going for, but you will probably end up with a good deal lower set-point. Good info for those that want significant more power out of their 22 F&T. It would also support a 25 cal top-end.

 

[SqrlHntr]

Thanks for the info and going overboard and taking the time with the pictures.

Only fitting the Huma on the one end is what I thought, but was hoping it was more like the Huma plenum in prod/discos/max.

While the easy route as far as fitting, I could go with Huma. I am concerned its slow fill won't work well on the SAM. Thanks again.





You will definitely have big enough plenum for a 177.  Not sure of the power level you are going for, but you will probably end up with a good deal lower set-point. Good info for those that want significant more power out of their 22 F&T. It would also support a 25 cal top-end.

Y’all are very welcome. I’ll be sure to post the chrony #’s and settings/tune results. The .22 FT is next with the same exact setup, parts and prep, but with larger ports. Nobody warned me about the rabbit hole. 

 

[lennyk]

some ppl have machined a blank gauge block without the threaded gauge hole and with large internal dia as a plenum

 

[TiredRooster]

This is an interesting post. I have a .22 Marauder FT model and my baffles will easily just fall out. They are definitely not glued or adhered within the shroud in any way.

That is interesting. Mine were both lodged and broke when trying to remove. When did you purchase yours? mine were both recently, past few months. Wondering of they are out of round, a qc issue maybe. Another forum had a comment about the baffles being stuck.

I purchased my FT model about three years ago. It's been a wonderful rifle.

 

[FuzzyGrub]

FWIW: The crosman engineer responded to the other thread I mentioned. He indicated that the tight baffles were a supplier problem that has been rectified.



Lenny,

I don't have means to make my own, but used modified gauge block to bridge vent on Fortitude when I converted to 25 cal. I will probably do something similar on the SAM. I also prefer having the gauge on the plenum.