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Ammo Benjamin Marauder .22 repeater with synthetic stock: Part 3

Benjamin Marauder .22 repeater with synthetic stock: Part 3

by Tom Gaylord, a.k.a. B.B. Pelletier

Benjamin Marauder .177 caliber Part 1
Part 2
Secrets of loading the Benjamin Marauder magazine
Part 3
Part 4
Part 5
Part 6
Fixing a Marauder magazine
Part 7
Benjamin Marauder .25 caliber Part 1
Benjamin Marauder .25 caliber Part 2
Part 3
Part 4
Benjamin Marauder .22 repeater with synthetic stock Part 1
Benjamin Marauder .22 repeater with synthetic stock Part 2

Benjamin Marauder with synthetic stock

New Benjamin Marauder with synthetic stock has all the features of the classic Marauder in a lighter, trimmer package.

Today, we’re looking at the .22 Benjamin Marauder with synthetic stock and establishing how it’s shooting over the chronograph. I said last time that I would test it at 2,500 psi; and if I got reasonable accuracy and shot count, I would go with that. But if any changes needed to be made, today is when they would be made.

I had no idea of what lay ahead of me! I began by loading 10 Crosman Premier pellets, which would be the standard pellet for the rifle. I knew going into this test that I wanted to shoot .22 Premiers at around 820-860 f.p.s. At 840, they produce 22.41 foot-pounds, which is a reasonable number for a middleweight .22 pellet in the Marauder.

Here are the first 20 shots, after which I will discuss my thoughts.

1        899
2        903
3        900
4        899
5        895
6        893
7        885
8        887
9        885
10     886
11      879
12      875
13      867
14      866
15      859
16      858
17      851
18      851
19      842
20      839

My thoughts
Okay, a couple things jump out right away. At 900 f.p.s., this rifle is shooting way too fast for its power potential. And notice that after the first few shots, the velocity decreases steadily. That’s more like a Korean rifle that’s been set up for screaming power and no shot count! I’m proven correct when the velocity declines starting with the fifth shot. By shot 20, the rifle has lost about 60 f.p.s.

The rifle jammed twice during this run of shots. They were the first and second jams I’ve experienced with a Marauder in all the years I’ve been shooting them. I’ll keep an eye on this.

The rifle was shooting too fast to be of any practical use to me. So I took the action out of the stock and adjusted the power screw. Read Part 4 of this report or the owner’s manual to learn how this is done. The power screw was out 2.5 turns, so I adjusted it in a half turn, to 2 full turns. Then, I shot the next 20 shots.

1       814
2       819
3       817
4       817
5       816
6       814
7       819
8       818
9       818
10     816
11     819
12     819
13     817
14     812
15     814
16     812
17     813
18     813
19     812
20    809

My thoughts
Now, the rifle is shooting a little slower than I’d like, but it’s very close. Note that there are a full 20 shots in this string. The maximum variation is only 10 f.p.s. I thought I could live with that, so I reinstalled the locking screw and turned it in. And that’s where a problem happened. When the locking screw touched the power adjustment screw, it also turned it in — all the way to the bottom. I removed the locking screw to confirm this.

So, I backed out the locking screw and then backed out the power screw 2 turns. The next 3 shots were faster than the previous string of shots.

1 832
2 827
3 826

Also, there was a jam during the firing of this string. Time to stop and assess where things are.

My thoughts
The rifle was not performing like a Marauder. It jammed and wasn’t adjusting the way I expected it to. Could there be even more things that I needed to check? What would happen if I filled the rifle to 3,000 psi, instead of the 2,500 psi recommended in the manual?

3,000 psi fill
With the adjustment screw left exactly where it was, I installed the locking screw but didn’t tighten it once it connected with the adjustment screw. Now, I was ready to test the rifle on a 3,000 psi fill.

1       861
2       863
3       863
4       865
5       862
6       863
7       861
8       858
9       859
10     859
11     863
12     857
13     863
14     859
15     860
16     861
17     861
18     860
19     858
20     856
21     858
22     852*
23     826
24     847
25     842

*Last useful shot

Okay, this rifle was not set up for 2,500 psi at all! It was set up for 3,000 psi. And the way it now shoots is exactly what I want. There are 2 full magazines per 3,000 psi fill, and they will average around 860 f.p.s. I’m going to forget about the 2,500 psi fill because the rifle is giving me what I want at 3,000.

There was another jam when I ran this string, making 4 jams in all during this test. Clearly, this magazine may have to be adjusted or replaced.

I like the way the trigger is adjusted. I can feel some movement in stage two, but it’s light and repeatable.

Discharge sound
This .22-caliber Marauder is more like a .177 than a .25. It’s very quiet. Maybe that’s the new silencer design at work. I don’t know. Whatever it is, I like it.

This test was a surprise to me. I was so certain that this Marauder would be just like the others I’ve tested; but as you can see, it isn’t. That leads me to wonder if there are other surprises in store for me down the road.

The jamming magazine is the first encounter I’ve had with a bad Marauder magazine. That’s actually good because it forces me to go through the same steps that a new buyer might have to go through for a similar problem.

I probably cut through some of the tuning problems quicker than a first-time buyer would because I’ve tested so many other new airguns. When the results you’re getting aren’t what you expect, It’s time to do some experimenting. I’m referring to my filling the gun to 3,000 psi after the second shot string.

What’s next?
I’ll try to fix the magazine, which seems to need more spring tension. I’m also going to order a spare, just in case. Next time, I’ll begin testing the accuracy at 25 yards. Testing with other types of pellets will occur at a later date, but we’ve waited long enough to see how this new Marauder shoots…so that’s next.

author avatar
Tom Gaylord (B.B. Pelletier)
Tom Gaylord, also known as B.B. Pelletier, provides expert insights to airgunners all over the world on behalf of Pyramyd AIR. He has earned the title The Godfather of Airguns™ for his contributions to the industry, spending many years with AirForce Airguns and starting magazines dedicated to the sport such as Airgun Illustrated.

48 thoughts on “Benjamin Marauder .22 repeater with synthetic stock: Part 3”

  1. BB I’m glad you gave the 3000 psi fill a try. That’s more what I’m use to with my Marauders and my 1720T.
    I got them turned up in power with a few mods to the air transfer valve as well as a different spring for the striker. And no I don’t have the spring adjustment cranked all the way up. I have about 4 turns on my striker spring adjustment with a 10# spring. (and no the guns are not violent in any way when they shoot) But I do have my striker adjusted at only 1 turn.

    So yes the striker has alot of distance to travel with the striker adjusted at only one turn. So when it hits the valve after the sear releases its got some fpe behind it. I have the stock spring in the air transfer valve shimmed with a flat washer also.

    If you took a old Marauder and filled it to 3000 psi it will maybe get valve lock. My guns can be filled to 3200 psi with a very consistent shot string. I think they even may want more pressure but I’m getting good results at 3200.

    So if they changed the air transfer valve on the new Marauder maybe that’s why your able to do 3000 psi in stock trim. It sounds to me like there is more beneath the skin that meets the eye on the new Marauders.

    And si.
    You were asking BB about your accuracy of your Marauder and we were talking about how the shroud was mounted to the reciever And this was the conversation we had.

    “Gunfun1 Says:

    December 12, 2013 at 7:23 pm

    Something that was wrong with my Marauder pistol is the threaded piece that is attached to the reciever that the shroud screws onto was not square.
    So when I screwed the shroud on it spun out of round.
    If I loosened the shroud just a little it would make the barrel follow and change the Point Of Impact big time.
    It would bump the shroud depending on how tight I had the shroud tightened.
    Ihope your gunsmith didnt have that going on and tryed to correct it with the barrel band.


    Gunfun1 Says:

    December 12, 2013 at 7:34 pm

    It should say.
    The shroud would bump the barrel band in different locations when I loosened the shroud a little.


    si Says:

    December 12, 2013 at 8:00 pm

    I’ve seen a video where a guy screwed his shroud into place on the rifle, cinched it lightly, then backed it off a turn or so. Seems like this might eliminate the problem? I don’t think the shroud has to be cinched to the receiver to stay in place”

    I read yesterday on the topic about the scopes that you had good results this time out shooting but you wasnt sure what helped. Do you think that was part of the problem or was it because you took the baffles out is what I believe you said. If thats so then I would say the shroud was pulling the barrel around. Tell me what you think.

    • But does reinforce my suspicions — as my .177 Marauder’s factory settings centered on 2700-2200. However, seeing that final nice FLAT velocity result has me wanting to tweak the flow adjustment screw on mine — If I ever get that 10m basement access (my parents are STILL moving out after a year!) so I can set up the chronograph. I was getting 18ft-lb with .177 Barracuda Match as-is, a slight drop in peak velocity in trade of a long flat velocity would be nice (and I can always then fiddle the pre-load and stroke length if I need to bring the velocity back up a tad).

      • I have the air flow transfer screw adjusted one and a half turns out from closed.

        It reduces the fps but you get more usable shots per fill. Sames as having a smaller hole in the tranfer port orifice.

  2. Truly a fascinating report. Lots of mental notes getting filed away here.

    Regarding the “jams” you’re reporting here: not having shot a Marauder yet, I’m curious to the specifics of what you mean by “jam”.

    – Were all the jams the same, or did you see different types?
    – What happens in a jam? Is it simply a pellet misaligned with the breech?
    – Would they be inherently magazine related, or not necessarily?
    – What did you need to do to clear them?

    (I’m at least somewhat limited by my long experience with firearm malfunctions. I tend to think in those terms, and may not yet be aware of a consistent airgun vocabulary. 🙂

    • Kevin,

      All the jam,s were the same. I pulled the bolt back and it would not go forward, even though there were pellets left in the magazine. To clear the gun I had to tap the magazine out of the gun. The pellet was always crushed sideways, once the magazine was out.


  3. I had a similar problem with my Monsoon and the design of the magazine is almost identical to the Marauder magazine.

    I got the Monsoon with one magazine and had no problems with it. But the gun was getting 36 good shots out of a fill so I ordered two more magazines. I wanted to load up all 3 magazines with pellets at one time for when I went into the woods or something. One of the new magazines I got was good but the other one was having a similar jamming problem as your Marauder.

    When I loosened the cover a little to make sure it was free and rotated the cover counter clockwise and let the cover rotate back closed it still was real slow.

    I took the cover off and wound the spring one revolution tighter. Put the cover back on and ain’t had no problem yet. And that really has to work right on the Monsoon if you want to make shots as fast as you can pull the trigger.

  4. BB- yesterday I bought a Diana (Milbro) 27. It has 2 small threaded holes and is marked for scope. What kind of current mount can I adapt for this rifle? Should the holes be enlarged for stronger screws? From what I have seen on the internet, the original scope for this rifle was small,and was made of lightweight plastic. Thank you, Ed

    • Ed,

      I have never seen a Diana 27 with a scope. They have a raised V-block at the rear of the receiver for a peep sight, but no scope.

      I think those holes are either put there by an owner, or Milbro made a model I’m not awae of.

      So I can’t help you with the mounts. But the 27 doesn’t recoil much so you can get away with a light scope and mounts.


  5. I had a factory declining string with my new 25 cal Syn rod, too. Even at 3k fill. I have seen others reporting the same. Interesting find with the jam nut. I wonder if that is what is causing the issue? Mag is probably the jam issue. I’d just get another, and try to fix that latter. If the new one jams, time to did in.

  6. Not too bad, but I find my disco gives me 40-50 useful shots. I can claim this due to the fact I just installed a dual tank system on it. Haven’t made it a repeater yet, but I’m working on it. I almost have it firing at it’s maximum potential now. I have to put in an adjustable hammer and heavy hammer spring and I’ll have it performing better than a marauder. Got some big money in this disco now. Still not done throwing money at it yet. You might wonder why I’m putting the money in it. Because I can.

  7. BB,
    Situations such as this are why I asked about single-shot capability without the single shot tray. Multi-shot is useless/not desirable to me for the most part, anyway, but it seems like if the multi-shot mechanism is messed up, the whole contraption is compromised, whereas single shot capability would make it usable or even preferable to some of us. Even more so on the .25, where it would be more practical to make one’s own “pellets”.

    On another note, is the inconsistency in velocity at 2.5K fill likely to cause an impression of inaccuracy (assuming Luddites like me who do not want to mess with a chrony)? It looks quite extreme. At some point, you would think that a simple regulator and factory standard fill pressure requirement would be a good alternative. I know I get annoying beating this dead horse, but I think there is a large number of rimfire shooters who would be highly attracted to this style of PCP, if it worked reliably out of the box and didn’t require any tinkering. Even if it were perfect, it still has the price difference working against it, plus it seems like pellets are catching up to .22LR fast in price, disregarding the recent frenzied and somewhat artificial inflation of .22LR.

    • I just went from a 12 inch .177 cal. barrel to a 18 inch .25 cal. barrel on my Talon SS and I had to lower my fill presure on the gun to get the gun back to a reasonable fps and shot count. A yes I used my chrony.

      • GF1

        I found my TSS .177 to be a squirrely air sucker at first. A short .177 barrel just did not seem to work easily . Took a lot of fooling around. Works better in .22… even with a short barrel.


        • TT
          Aint it amazing how switching how long the barrel is or changing calibers can effect the fill preasure on a pcp gun.

          The heavier the pellet is on the Monsoon the lower you have to go on fill pressure for the bolt to cycle right.
          Try throwing in a magazine that aint working right along with trying to find the fill pressure so the bolt cycles correct can end up being complicated if you dont know what your doing.

          The reason I brought up the Talon was for an example. Every pcp that I have messed with I had to find that just right fill pressure for whatever tune it had.

  8. Hey BB, I always get off work so late, seems like I’m always the last comment when I do. I was glad to see you give the Marauder report today, I have been really enjoying the fresh look as I have been starting out with mine. If you remember I had alot of trouble with magazines when I got mine, I think there may be some quality control issues at crosman. I was worried about the cracks in my magazines, at the holes the spring end sits in letting the spring loose, perhaps thats whats going on with yours. Also my rifle came with a tag on the triggerguard that said it too was setup for a 2500 psi fill. I dont have a cronograph, yet, but while getting to know my rifle target shooting, it seemed like it wasnt getting the shot count others had gotten. It would start to spread the shots out and lose the accuracy. I tried moving up on my fill pressure and things got better, I kept going to see if I would start to get valve lock, or notice any problems and got all the way to 3000 without any. Ive been shooting from there and have had good results. I know I need a crony to be sure exactly where my best fill is but its for sure not the 2500 crosman said it was. I am a huge fan of their products and hope they are not going the way of alot of companys and sacrificing quality for speed or money.

    • Bill
      I can tell the same way as you do about my shot string and fill pressure.

      I filled My Talon SS to the same pressure fill that I was using with the .177 cal. 12 inch barrel with the 10 grain JSB pellets which was 2400 psi. (which is what I finally have found to be the best fill pressure)

      Then shot the 31 grain .25 cal. Barracudas with the 18 inch barrel. Oh and I left the power wheel set at 2 which is a less amount of hit on the air valve. On my gun for some reason power only increases a little if I turn it up and I just waste air.

      But I could immediately tell the fill pressure was to high because the point of impact was raising with each shot. So I shot a few more shots till the POI stabilized and wasn’t climbing. And then I checked the gun for fill pressure to see where it was at. It was about 200 psi less than what the .177 was at.

      I chronyed the gun after that then found it true to what the POI was when I was shooting. The gun had a lower fps at 2400 psi and started getting more fps as I shot the gun. Soon as I got to 2200 psi the fps stabilized and I had a good 40 usable shot string at that setting.

      So I would say you can tune the fill pressure of your pcp gun by just shooting the gun if you know what to look for. (watching POI) But as far as tuning the gun for power out-put I would say the chrony is it. Although you could shoot into wood to see the amount of change in penetration the pellet made at different settings also I suppose to check your power tune.

    • Bill,

      I’m glad you finally got to see this report. I was thinking of you and others who are new to the Marauder when I tested this rifle. As you can see, things aren’t always rosy when I test airguns, but I will always try to tell you what I see. That way we’ll all know what to expect from these guns.

      I hope I can solve the magazine problem, though I have requested a new replacement, just to be sure.


  9. BB, I am surprises at how few shots you got on a 3000 psi fill. I have never owned a Marauder but most that I have read about claim more consistent shots than you were getting. I wonder if there is still further tweaking that will help.

    As for the Diana 27, I will pass that question along to Mike Driskill and see if he knows about it.

    David Enoch

  10. Not sure why it was not designed better so you can adjust the velocity without taking it out of the stock…a small u-shaped gouge mod around the air metering adjustment screw helps to get the wrench in there without the extra hoops.

      • I should say this also.

        I really don’t adjust that any more after I found the sweet spot for the shot count and the fill preasure I want to use. But I sure did adjust it a lot in the beginning when I first got my Marauders.

        I act like that adjustment doesn’t exist anymore. If I want more power I will just add one or two revolutions to the spring adjustment. Then back the spring adjustment back off the one or two turns to my normal setting when I don’t need the extra velocity any more.

        That works out nice when I’m in the woods with my .25 cal. Marauder. If I see a bigger critter the Allen wrench comes out and I give the spring a few more tuns.

        And when you chrony the gun the two turns of the spring make a good amount of difference. Then I back the spring back off when I think I dont want that extra power any more. Pretty easy. All I worry about on the guns now is the spring adjustment after I got the other stuff figured out.

          • Pete
            I think you mean the locking set screw that touches up against the Power adjusting screw.

            (I don’t like calling it a Power adjustment screw. I think it should be called the Transfer port air flow adjustment.)

            But if that’s what your talking about. I do use the locking set screw just touching the adjustment screw like BB said. But before I put the locking set screw in the gun I use a drop of Blue Loctite on it then thread it in just till it stops. And yes you can get it out again if you need to. It doesn’t lock it up hard. It just keeps it in place.

            If you have messed with any Crosman guns. That’s what I believe they use on set screws that are in barrel bands and among other things. And let me know me if you meant something else.

  11. This article is pretty scary. It seems like the shooter has to be willing to spend a bunch of time with a chrony to make the M-rod shoot to its potential. Who would want to do that? The shot count per fill is poor for a rifle this size.
    I’m short on time and patience, and am glad PA sold me an AA510, you fill it with air and you’re good to go.

    • Define “its potential”…

      Do you want a long, mid/low-power shot string? Or maybe you want a max-power string of one magazine? What velocity variation will you accept (since velocity variation tends to correlate with group size). Do you want a low-pressure configuration (to support easier hand-pump usage) or peak pressure (you are refilling from a 4500PSI carbon-fiber tank).

      • That’s easy, I think it should have at least 35 good shots at around 900 fps w/14.3grpellets new, out of the box no adjustments. If a guy wants to dial it down to a plinker, fine. But the thing is supposed to be ready to shoot. 22 shots is terrible for a rifle with 215cc air.

        I’ll bet most 4500 carbon fiber guys don’t get M-rods, they have higher budgets and don’t want a project.

        • Well… Mine is .177 (and wood); as shipped it gets around 35 shots between 2650PSI to 2200PSI, min vel 861, max 883 — using the 10.7gr H&N Barracuda Match pellet. Produces ~18ft-lbs.

          • That sounds a lot better. My main point is the article doesn’t show the marauder in the best light. Your results are better. Im interested in the synthetic mrod for plinking squirrel and targets, all very informal.

            I have an 88ft3 3300psi tank so I could fill a Marauder dozens of times to 2650psi.

  12. That sounds a lot better. My main point is the article doesn’t show the marauder in the best light. Your results are better. Im interested in the synthetic mrod for plinking squirrel and targets, all very informal.

    I have an 88ft3 3300psi tanko filling is easy.

  13. I had similar jamming issues with my .22 Marauder (original wood stock version) using the same Crosman Premier pellets as you had tested this new version with. I found that the tolerance in the magazine allowed the pellets to slightly rotate in the mag. I switched to the RWS Superdomes (which I normally use) and the jamming issue stopped completely.
    My son really liked the Premiers for his single shot though…….

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