Tuning Low Power Tune - Marauder Field & Target

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thofmann

Member
Jan 16, 2022
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CA, United States
New member here, and new to the PCP world. I recently bought a .177 Marauder Field & Target rifle. Due to my location, I mostly do close range target shooting. The Marauder F&T has way more power than I need, so I am interested in tuning it for lower power. 12fpe with an 8-ish grain pellet would be fok, 8-10fpe would be even better.

I have read some articles from Tom Gaylord on Pyramid Air where he adjusted an unregulated Marauder down to that range. My question is would that work with a regulated Field & Target? From I have read, it does not appear to be possible to get much more power out of the F &T because of the plenum volume, but what about the other way around? So other words, being new at this, I am wondering if adjusting the hammer spring, hammer stroke, and the valve metering screw will have same effect on F & T as an unregulated Marauder if I am trying to lower the power? Or does the non-adjustable factory regulator change things?



Thanks!

Thomas
 
Hmm I'd have to know the marauder field and targets regulator pressure to make sound advice here. I own the gun and tuned it up from the factory just a bit so I know there is some room for manipulation of power but it's all hammer spring tension and hammer throw adjustments. To get it that low I suspect that you would need to take the gun apart and put in a smaller transfer port. I'm j ok t really sure exactly how far down you can go with just the hammer spring adjustment. Changing the transfer port is only a 45 min job for a new guy to watch youtube disassembly videos and follow along on your gun. That's how I started and now I can tear down and rebuild one in about an hour. All you need to do is remove the receiver from the tube and replace the transfer port. You don't need to tear down the whole gun. Just make sure that if you do take it apart remember to pull the trigger and hold it down when you are tightening the bolts back up on the receiver. If you don't you absolutely will break your trigger..... Ask me how I know. 🤔
 
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What you may want to do is not void your warranty.

Probably need to replace the hammer spring with a weaker one bring the factory spring and end cap to your local hard ware store such as Ace Hard ware buy weaker spring same outer diameter with slightly thinner wire easier to scrunch.

Buy several O Rings to do a B Staley hammer buffer mod.

These should lower your power to what you want or below. Watch both videos measure the inner diameter of the tube and bring the hammer with you eye ball the outer diameter of the o rings you need to buy to slide in to the tube. It will lessen the power as well and stop wasting air.

Adjust over your crony.

Cut the spring shorter if lower power is desired.

Do not alter the factory spring keep it some place safe.

Since yours is regulated you probably don't need to run a restricted transfer port.

Weaker hammer spring and the o ring mod should get you there.

I wouldn't touch the regulator.

Less to disassemble too. 

https://youtu.be/uhtPan7RCU4

https://youtu.be/flIxgQXC3r8




 
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I had two regular.177 marauders I built to be 12fpe. They both shot really well and got tons of shots. I used huma regs and no gauge adapter.

I would start buy bottoming out your hammer throw and spring adjustments and see where that starts. You may end up with the hammer in free flight. 


If this is too low on power bring in more spring tension. But if both backed all the way out and it is still to hot choke up the tp some.



on mine because I started from reg Marauders and added the reg I had it set low with a fully opened transfer port. I kept the hammer setting all the way on low and I think I clipped a coil on the hammer spring. Both rifles were basically silent.
 
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The "right" way to do it, would be turning the regulator down from the stock 2K to 1.6K psi. The regulator is adjustable but needs to be re-locked down with VC-3, or equivalent. It would be about 1/2 turn CW on the adjuster. But, there is no plenum gauge to verify. Full gun dis-assembly required.

The HS adjustment or spring change will not get you there by itself and will not be a decently flat string.

The "best" way without opening the gun, would be to turn in the velocity adjuster. While it will get you to the lower power, it will not be more efficient, meaning shot count will not go up much.

I haven't done the BSB on a regulated gun, but might produce satisfactory results without going "deep" into dis-assembly. You will need to place four -118 O-rings against the valve, infront of the hammer.


 
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Thanks everyone for the input! Looks like there are more ways to get to lower power than I would have thought. Being a brand-new gun, I would not want to void my warranty just yet and adjust or replace the regulator. So, I think I will start with the velocity adjuster and perhaps the hammer adjustments. Living in SoCal, I have 10-15 yards to work with in my enclosed back yard, the nearest outdoor range with a 50+ yards is a 1.5 hour drive. I may not get more shots, but I could easily turn the power backup when I get the chance to shoot longer distances.

Just out of curiously, because noise is always a concern here, does turning down the power via the velocity adjuster or adjusting the hammer spring lower the volume any?

Thanks again.

Thomas
 
Upvote 0
Thanks everyone for the input! Looks like there are more ways to get to lower power than I would have thought. Being a brand-new gun, I would not want to void my warranty just yet and adjust or replace the regulator. So, I think I will start with the velocity adjuster and perhaps the hammer adjustments. Living in SoCal, I have 10-15 yards to work with in my enclosed back yard, the nearest outdoor range with a 50+ yards is a 1.5 hour drive. I may not get more shots, but I could easily turn the power backup when I get the chance to shoot longer distances.

Just out of curiously, because noise is always a concern here, does turning down the power via the velocity adjuster or adjusting the hammer spring lower the volume any?

Thanks again.

Thomas
Click to expand...







If you don't want to mess with the regulator and just turn the hammer spring all the way back and then play with hammer throw. But I still would recommend the experiment with different TP, they can be ordered from corpsman and will not void warranty. 
 
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Just out of curiously, because noise is always a concern here, does turning down the power via the velocity adjuster or adjusting the hammer spring lower the volume any?

Thanks again.

Thomas
Click to expand...

Yes, the report will be less with less powerful shots.

Before making adjustments, record where yours are at, so you can get back. On HS and HT, count the turns from where they are, until they fully stop, going CCW. On the velocity adjustment, remove the jam cap, and count turns CW until it stops, then CCW to get back to the setting of your choice. Be careful when re-installing the jam cap. It will easily start turning the adjustment screw further in.

The 1720T transfer port is too short to fit in a Mrod. There is also no need when you can just use the velocity adjuster to strangle off the port.
 
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