25 caliber marauder power tune

[Cbourbeau32]

Hello, I bought a used 25 caliber gen 2 marauder a year or so ago. It's very accurate with jsb 33.95 gr and 25.39 gr (a little better with 33.95). Anyway, it came with a Huma regulator and Tim Hill valve. The reg is set to 2100 psi and don't know what the specs are on the aftermarket valve. I am wondering if 850 fps with the 33.95 gr is doable. Right now it shoots the 25.39 at 850 and the 33.95 just under 700 if I remember correctly. I'm not sure what the top end psi is for the Huma regulator but I would like to keep it regulated. I hope my question makes sense.

 

[Airgun-Revisions]

If the 850 is accurate the 34g will be doing 760-780. That’s not bad at all for accuracy. If you want a tad more power up the reg to 2200 and that should net you 875 and still be good and accurate for both cal’s.
2100 to 2250 is the norm for a reg setting in the Marauders.

 

[Dan25]

Hello, I bought a used 25 caliber gen 2 marauder a year or so ago. It's very accurate with jsb 33.95 gr and 25.39 gr (a little better with 33.95). Anyway, it came with a Huma regulator and Tim Hill valve. The reg is set to 2100 psi and don't know what the specs are on the aftermarket valve. I am wondering if 850 fps with the 33.95 gr is doable. Right now it shoots the 25.39 at 850 and the 33.95 just under 700 if I remember correctly. I'm not sure what the top end psi is for the Huma regulator but I would like to keep it regulated. I hope my question makes sense.

You might research a member by the name of ajshoots. He was the Marauder power tune guy a few years ago. Yes you can turn one up to that power level but it takes a bit of doing to get there. Go ahead and get a chronograph if you don't already have one.

 

[dizzums]

i get 900+ out of mine with 33's .. go back to hill and get the lightweight hammer and power spring .. the TP also needs to be opened up, hill uses a plastic fuel line straw to replace it along with a drill and burr in the kit ... the reg is dead weight if you ask me, youll get 2 clips in the sweet spot of some hard hitting 33s .. your not building a bench cream puff right ... id replace the reg with a depinger and call it gravy ..

 

[MileHighAirGunner]

Hello, I bought a used 25 caliber gen 2 marauder a year or so ago. It's very accurate with jsb 33.95 gr and 25.39 gr (a little better with 33.95). Anyway, it came with a Huma regulator and Tim Hill valve. The reg is set to 2100 psi and don't know what the specs are on the aftermarket valve. I am wondering if 850 fps with the 33.95 gr is doable. Right now it shoots the 25.39 at 850 and the 33.95 just under 700 if I remember correctly. I'm not sure what the top end psi is for the Huma regulator but I would like to keep it regulated. I hope my question makes sense.

Contact Tim https://hillairgun.com/contact-form-7-id1447-titlecontact-tim/
He’s always been very helpful with me and he will answer your questions and help guide you how to set up your rifle using his valve and parts.

 

[SqrlHntr]

If its an Huma reg with an XL plenum you should be able with a bump in pressure. Longer barrel helps too. Measure the barrel port, it may have been opened prior, Tim’s kit has you drill to .160 to match the transfer port. The PEEK striker eliminates any further striker adjustment so tuning is easier with Hammer spring only. The regulated kit comes with the lightest Valve spring (#7) and hammer spring, light hammer and PEEK striker. With Tim’s regulated kits, I find if you need more than 3 hammer spring turns in to get the velocity , a change out of the 262 spring to a slightly heavier one and be right about 1/2 turn in to match velocity. Any more than 4 and I find a spring change is needed. In the case of spring rattle, some of Tim’s springs are shorter and have a free flight effect, use an foam earplug.

Heres tim’s included tuning instruction for his kit for reference

Check out Stearnes’ articles on regulated pcp’s and tuning as well.

An Introduction To The PCP Regulator. Don’t Ignore The Plenum!

Producing constsnt FPS in a PCP with varying air pressure is tough. Instead why not use a PCP regulator to produce a constant pressure at the valve?

hardairmagazine.com

Tuning Regulated PCP Airguns - Hard Air Magazine

The first thing you need to understand when tuning regulated PCP airguns is that for any PCP there is a maximum velocity for a given pellet,

hardairmagazine.com

 

[Dan25]

Cool thing about this place is all you have to do is ask and you get flooded with years' worth of experience, just for the asking.

 

[davhowrd]

Welcome to the madness "Cbourbeau32", depending on the level of power you searching for; this could be a short or long and bumpy road. I have personally seen 25 cal marauders well tuned with mods done; push 44 grain slugs out past 980 fps and still maintain a decent shot count.