Benjamin Marauder POI issues

[Jack 50]

I recently picked up a Benjamin Marauder Gen 1 .25 with the GM barrel. It has been a disappointment so far trying to get consistent shot placement. The pellets I've tried so far are JSB King Heavy diablo 33.95 and JSB King 25.39. Both struggle to keep a 1" group at just 10yrds. Right now I'm shooting 850-900 FPS but thinking about tuning it down a bit. Also considering trying a barrel band.
I also have a Air Arms S510 and an Avenger that are pellet on pellet guns out considerably farther which makes it even more frustrating.
Any advice is appreciated.

 

[3Crows]

I recently picked up a Benjamin Marauder Gen 1 .25 with the GM barrel. It has been a disappointment so far trying to get consistent shot placement. The pellets I've tried so far are JSB King Heavy diablo 33.95 and JSB King 25.39. Both struggle to keep a 1" group at just 10yrds. Right now I'm shooting 850-900 FPS but thinking about tuning it down a bit. Also considering trying a barrel band.
I also have a Air Arms S510 and an Avenger that are pellet on pellet guns out considerably farther which makes it even more frustrating.
Any advice is appreciated.

The M-Rod comes with a barrel band #11. Check it is aligned and the two screws #10 are tight.

One thing you might do, not as complicated as it might sound. But remove the shroud and the pucks, spring and the air stripper and shoot with the bare barrel. You can also now check the crown. Inspect the pucks #15 for clipping.

Make sure the shroud and barrel band are not preloading the barrel inside.

With the shroud removed check the screw #18 is tight and that #19 is pressed tightly to the breach assembly. Also check that the barrel retention screws #21 (two of them) are tight. Check the O-ring #9 is in place on the air stripper # 8.

Marauder .25s are generally pretty accurate rifles. My four are .




I realize you have a Gen 1 but the parts are similar that I am pointing out. IMO, the GM barrel is NOT as accurate as the Gen 2 Crosman barrel is now.

 

[Ta-Ta Toothie]

Maybe you got some clipping going on.

 

[AlanMcD]

1" at ten yards is horrible, so something definitely is wrong. The advice above is all good, but do be sure that when checking the barrel tightness in the breech not to over tighten the grub screws - The barrel is not really thick there, and it is possible to over tighten and dimple the inside of the barrel.

I have several Gen 1 Marauders, and one of the nice things is that you can pull the bolt and then have access to clean it or push a pellet though the barrel with a rod from the breech end. You could push a pellet through it to make sure all is well internally in the barrel.

Also, make sure that the scope is good and that the erector tube is not floating in it - adjusting a scope down to hit the aim point at ten yards can exceed the capability of some some scopes in terms of having too little load on the spring. You could do a quick check of that by giving the turret a couple of full turns to put more load on the spring and see how it groups - the POI will be well below POA when you shoot, but if the groups tighten up that would be your issue.

For the results you are getting, something is either loose, pellets are clipping, or the scope is part of the issue. I think I could put the pellets in mine backwards and still beat those results . . . . Good luck!

 

[3Crows]

Yes, indeed, the scope. I have a Marlin 336SS PB that has always been accurate. It has a nice relatively new Leupold scope on it. Checking zero for deer season it was all over the place. Scope! Returned to Leupold under lifetime warranty for repair/replacement, came back good as new and the Marlin is on the money. Something is moving around, the scope internals, the mounts, the barrel.

Yes, pushing a pellet through the barrel is a good plan to see if it moves without restriction until nearly at the muzzle where there is a choke.

 

[Jack 50]

The M-Rod comes with a barrel band #11. Check it is aligned and the two screws #10 are tight.

One thing you might do, not as complicated as it might sound. But remove the shroud and the pucks, spring and the air stripper and shoot with the bare barrel. You can also now check the crown. Inspect the pucks #15 for clipping.

Make sure the shroud and barrel band are not preloading the barrel inside.

With the shroud removed check the screw #18 is tight and that #19 is pressed tightly to the breach assembly. Also check that the barrel retention screws #21 (two of them) are tight. Check the O-ring #9 is in place on the air stripper # 8.

Marauder .25s are generally pretty accurate rifles. My four are .




I realize you have a Gen 1 but the parts are similar that I am pointing out. IMO, the GM barrel is NOT as accurate as the Gen 2 Crosman barrel is now.

The barrel band set screw on mine only snugs on the bottom tank. The barrel shroud is free floating in the top of the band. I already took the shroud off and tightened the screws. I also checked the #15 (baffles) to see if the pellet was touching any of them. When I first got it and found it didn't shoot good, I cleaned the barrel with patches and was very dirty. That helped some. Still have something else going on though.

 

[3Crows]

The barrel band set screw on mine only snugs on the bottom tank. The barrel shroud is free floating in the top of the band. I already took the shroud off and tightened the screws. I also checked the #15 (baffles) to see if the pellet was touching any of them. When I first got it and found it didn't shoot good, I cleaned the barrel with patches and was very dirty. That helped some. Still have something else going on though.

You can slip a thin O-ring over the shroud and push it into the barrel band to prevent movement. Works fine for me. There are 3D printed bands on eBay that are secure to both air tube and shroud.

 

[Motorhead]

Used rifle ... yes as suggested on barrel band, baffles etc ...
BUT ... BRUSH SCRUB and CLEAN the barrel too !!!
make sure breech o-ring is intact as well

 

[3Crows]

I did install a printed band on this M-Rod .25. I was not having any particular issue but I like to lean my rifles against a tree or room corner. So belt and suspenders, I installed the printed band loose, installed the OE band loose and shot the rifle several times. I then tightened down the printed band, then stuffed an O-ring into the OE band and tightened down it's set screws. Then I sighted in the rifle scope. It is sturdy and accurate.



I have been told, shouted at on this forum, by one member since placed on ignore that this was not good and the rifle would change POI with hot or cold. Hmmm, well, all I can say is I just got three HOSP kills, three for three, today at over 70 yards in 26 degrees weather and that band was installed and sighted in at near 100 degrees. Yeah, metal is better but aluminum expands and contracts also. But, I have rough cut a couple of aluminum HD bands and need to whittle them down and make them pretty, might get around to it some day .

I have read that folks have installed three set screws into the OE band to secure and center the shroud. Drilling such would be a PITA. Also Tim Hill has (or had) zero slop barrel bands for the M-Rod.

 

[Jack 50]

I checked the baffles again and may have found a mark on one so I reamed them all out about .008 larger. I also scrubbed the barrel which I usually don't do on airguns and then used a washer in the barrel band as suggested. It now shoots pellet on pellet at 10yrds! Can't wait for warmer weather so I can shoot longer distances. Now I'm going to tone it down a little to improve my shot count. Thanks guys!!!

 

[3Crows]

I checked the baffles again and may have found a mark on one so I reamed them all out about .008 larger. I also scrubbed the barrel which I usually don't do on airguns and then used a washer in the barrel band as suggested. It now shoots pellet on pellet at 10yrds! Can't wait for warmer weather so I can shoot longer distances. Now I'm going to tone it down a little to improve my shot count. Thanks guys!!!

One thing, I guess I did not mention. The barrel stripper also has an O-ring on it that fits into the ID of the shroud (#9 in PL). Make sure that is a good fit and in place on the stripper. If the O-ring is a sloppy fit on the ID the barrel and shroud may not stay consistently aligned.