Benjamin How to Tune Non-regulated Marauder?

[GregGeis]

I just acquired my first PCP rifle from a family member. It’s a ~2007 Benjamin Marauder .177. I have no idea what has been done to it, but likely nothing since it was purchased. It seemed to shoot pretty well, but I know I could get more out of it. It air locked the first time I pumped it all the way to 3,000 psi. Likely, the spring had just lost some tension and needed more preload, so I turned it in about 1.5 turns and it started shooting again. I’ve looked up tuning guides, I just can’t find one for a non-regulated Marauder, and I’m sure there are some basics I’m missing that would lead to a more successful tune.

First I was going to set the hammer spring tension. My first question is what pressure should I set it at? Max, or middle? I was going to back the tension back up and start turning it in slowly until velocity stabilizes.

It also has the hammer throw adjustment. Is there somewhere to start on it? From what I’ve read (for 2nd gen, not mine) people back it all the way out and turn it in 8x or so before seeing any impact. Is this something I should adjust or just leave it alone and don’t worry about it? My impression was it only seemed useful for trying to reduce your velocity further if it’s still shooting too fast by turning it in. I am guessing that’s sort of your only velocity adjustment, so turn it in to slow it down or out to speed it up after your hammer spring tension is dialed in?

Any other tips? I watched the AEA tuning guide on YouTube which was very helpful in learning the basics. But it was all based on a regulator. I’m sure non-regulated simplifies the process if you know what you’re doing.

 

[PigeonMan]

I used to own a marauder back in 2010. It's best when the pressure is about 1800-2600psi. Filling to 3000 isn't the best cause the hammer will have to strike harder to open then when the pressure gets around 2200psi the hammer is hitting too hard.

 

[Dr. Kralenstein]

Get a chrony. Otherwise, you're just shooting in the dark.

 

[3Crows]

You can start with the OM which is available on the Crosman website and without a chronograph you are whistling Dixie.

 

[Struckat]

I fill mine to 2700. No need for more as that is about the beginning of the sweet spot.

Go to Amazon and get the $30 speed meter China chrony.

You really need this to see what is happening as you adjust.

 

[SilentSquirrel]

@UDABEGGER
If you are really lucky, @nervoustrig will chime in and reference his work on tuning unregulated rifles.
He's one of the best

just my 2 scents
Edward

 

[6gun]

I just acquired my first PCP rifle from a family member. It’s a ~2007 Benjamin Marauder .177. I have no idea what has been done to it, but likely nothing since it was purchased. It seemed to shoot pretty well, but I know I could get more out of it. It air locked the first time I pumped it all the way to 3,000 psi. Likely, the spring had just lost some tension and needed more preload, so I turned it in about 1.5 turns and it started shooting again. I’ve looked up tuning guides, I just can’t find one for a non-regulated Marauder, and I’m sure there are some basics I’m missing that would lead to a more successful tune.

First I was going to set the hammer spring tension. My first question is what pressure should I set it at? Max, or middle? I was going to back the tension back up and start turning it in slowly until velocity stabilizes.

It also has the hammer throw adjustment. Is there somewhere to start on it? From what I’ve read (for 2nd gen, not mine) people back it all the way out and turn it in 8x or so before seeing any impact. Is this something I should adjust or just leave it alone and don’t worry about it? My impression was it only seemed useful for trying to reduce your velocity further if it’s still shooting too fast by turning it in. I am guessing that’s sort of your only velocity adjustment, so turn it in to slow it down or out to speed it up after your hammer spring tension is dialed in?

Any other tips? I watched the AEA tuning guide on YouTube which was very helpful in learning the basics. But it was all based on a regulator. I’m sure non-regulated simplifies the process if you know what you’re doing.

I too have a first gen marauder but mine is 25 and has a slightly different valve. Still the principles apply.

I fill all the way to 3000, my hammer travel set to max and my spring ended up near max.

This is just how I did it. With a chronograph shoot and turn the spring tension In on a full fill till you can get a little more than your target velocity. Pellets seem to universally like 850 fps and the trajectory difference for pellets is negligible to me for a bunch of noise and wasted air. Then I lessen the hammer travel till velocity is at the target speed and it shoots a whole fill as close to target speed and trajectory as possible . The transfer port is usually left open since it's under the stock unless you drill a hole in the stock to adjust it more easily. I closed my transfer until I saw a slight fps drop..... But only because I wanted 2 mags on a fill. Unfortunately I was chasing fps I couldn't get, so I tuned as above for least noise, with the best shot count and most consistency across those shots. I hope this is of some assistance to you. Best of luck, and below is what I've changed on my gen 1.

De pinger in the air tube
Bolt handle
Delrin shroud-to-barrel band sleeve for zero barrel movement.

I had a high flow valve pin and heavy spring back when I bought it that broke and I couldn't find them again but it made it a 1 magazine gun which kind of stunk for me anyhow.

 

[SDellinger]

Google tuning marauder air rifle. Airgun Nation has great info. Crosman put out explicit tuning info a few years back.

 

[SilentSquirrel]

What ever !

No worries
It's simple
You'll get the hang of it

 

[6gun]

Google tuning marauder air rifle. Airgun Nation has great info. Crosman put out explicit tuning info a few years back.

Probably the best advice.

 

[GregGeis]

Probably the best advice.

I’ve done that, I couldn’t find any on a non-regulated Marauder. Plenty on the Gen 2 and tuning for power.

 

[GregGeis]

you need a crony

I have one. Sorry, I could have made that more clear.

 

[GregGeis]

I too have a first gen marauder but mine is 25 and has a slightly different valve. Still the principles apply.

I fill all the way to 3000, my hammer travel set to max and my spring ended up near max.

This is just how I did it. With a chronograph shoot and turn the spring tension In on a full fill till you can get a little more than your target velocity. Pellets seem to universally like 850 fps and the trajectory difference for pellets is negligible to me for a bunch of noise and wasted air. Then I lessen the hammer travel till velocity is at the target speed and it shoots a whole fill as close to target speed and trajectory as possible . The transfer port is usually left open since it's under the stock unless you drill a hole in the stock to adjust it more easily. I closed my transfer until I saw a slight fps drop..... But only because I wanted 2 mags on a fill. Unfortunately I was chasing fps I couldn't get, so I tuned as above for least noise, with the best shot count and most consistency across those shots. I hope this is of some assistance to you. Best of luck, and below is what I've changed on my gen 1.

De pinger in the air tube
Bolt handle
Delrin shroud-to-barrel band sleeve for zero barrel movement.

I had a high flow valve pin and heavy spring back when I bought it that broke and I couldn't find them again but it made it a 1 magazine gun which kind of stunk for me anyhow.

Thanks! I’m just wanting accuracy out of this one and a good shot count would be welcome. I have an Avenge-X .22 coming for higher power tunes and tinkering. How do you know when your hammer spring is too strong for your valve? If I tune it at 3,000 psi and shoot it to 2,000 does it start making a noise when it doesn’t have enough push back?

 

[Gerry52]

Most of the airguns I have experience with have a sweet spot that's below maximum air fill. I've yet to come across one that shoots at maximum efficiency when filled to maximum PSI. I never even bother to fill mine to capacity anymore as I know they're most efficient & accurate starting at 100-150 bar below maximum capacity.

 

[6gun]

Thanks! I’m just wanting accuracy out of this one and a good shot count would be welcome. I have an Avenge-X .22 coming for higher power tunes and tinkering. How do you know when your hammer spring is too strong for your valve? If I tune it at 3,000 psi and shoot it to 2,000 does it start making a noise when it doesn’t have enough push back?

Your valve is different and may have a lower sweet spot. As for knowing about the spring tune, a chrono for monitoring diminishing returns and an ear out for a change in noise that is a little more poof than in used to be. That's the best advice I have. Sorry it involves a bit of tribal knowledge and feel. Your preference in tune is important too. I had to make the best of what I had on a full fill with mine being 25. As simply put as I can, I basically watch the chronograph and adjust things till i can achieve a happy middle ground of accuracy, noise, velocity, and efficiency is a function of those things sort of. Certain characteristics walk hand in hand from my 7 ft lb crosmans to my 70 ft lb fx stuff, efficiency tends to come with accuracy and low noise. Lmk how it goes