Thursday, November 5, 2009

Benjamin Marauder Baffle Modification

Several of the first .22 cal Marauder owners had some accuracy problems traced back to the pellets clipping the baffles in the shroud. The early baffles have 0.247" holes--fine for .177 caliber pellets, but a bit on the close side for the .22 cal--unless everything is perfectly concentric. Apparently, Crosman has fixed the potential clearance issue on the new .22 rifles. Many shooters have found that the early .22 cal guns will benefit by opening up the holes in the baffles to about 0.280". This does not seem to increase the gun's discharge noise at all.

I've had no pellet clipping issues with my Benjamin Marauder, nevertheless, as I was going to be away traveling with the rifle, I thought I'd eliminate the possibility. It's such a simple job, I'd recommend it in a second.

As always, step one is make sure the rifle is unloaded. It actually took longer to download the pics than to do the modification.

Remove the fill cap that covers the Foster fitting.

Find a 5/64 allen wrench and loosen the two set screws on the barrel band.

Pull the barrel band off the front.

Unscrew the end cap from the shroud.

Tip the buttstock up in the air and the o-ring and followed by the four baffles will slide right out. (If they don't slide out, it's no big deal--just go to the next step).

Grab the shroud and unscrew it from the breech.

You'll feel some slight resistance from the o-ring on the baffle mounted on the muzzle.

Slide the shroud forward off the front of the gun. If your baffles didn't fall out earlier, use a wooden dowel rod and push them out.

Personally, I doubt that this final baffle could clip the pellets. It's so closely centered on the muzzle and a snug, press-fit, I just don't think that it could be far enough out of alignment to make pellet contact. If you don't want to drill this one out, that's probably just fine.

Appears to be covered in lead dust.

If you want to remove it, a 7/16 open-end wrench placed over the barrel helps to remove it. I gave the wrench a smack from a small dead blow hammer and the cap popped right off.



A lathe, drill press, hand drill, maybe even a tapered reamer, would probably suffice to open the holes. I used the Taig lathe with a 9/32" drill bit in the tail stock.

Each plastic piece took about 10 seconds.



The aluminum end cap took almost 20 seconds.
Reassembly is in the exact reverse: Install the press fit baffle on the muzzle first. Hand pressure alone should seat it. Mine clicked as it bottomed into place. Slide the shroud back over and thread onto the breech. Re-install the baffles. The large open ends face the rear of the gun. Drop in the o-ring and thread the shroud end cap down. Finished.

While I was tinkering, I figured I'd clean the barrel, too. 9/64" allen wrench removes the bolt.



There's a small bushing on the bolt.

Pulls right out the back.

I very carefully pried out the small o-ring that seals the bolt nose. This was a pain as there's minimal working room in the magazine opening.

Cut a piece of brass hobby tube to fit into the bolt hole.

Like so. This will ensure I don't have to clean up JB Non-Embedding Compound from the inside of the bolt channel.

Cleaning rod goes right through. The brass tube is not a press fit. I simply held it in place with my hand as I worked. Patched the barrel clean then cleaned out the o-ring groove with a nylon bristle bore brush followed by the dental pick and a the corner of a cleaning patch. Reinstalled o-ring (more fun) then lubed the ring lightly with a diver's silicone grease and called it good.

Lubed the bolt with a dive grease and reinstalled the allen bolt/bushing. Almost forgot to mention, you can just see the screw on the top rear of the breech. It's got a spring loaded ball on the end that puts pressure on the bolt. Screw it in or out to add or subtract pressure on the bolt. Adjust to your liking.

If you don't feel like messing around with the baffles in your rifle, Crosman will simply send you the new parts if you've got an early model. It should take you about five minutes or less to install them.

7 comments:

Slinging Lead said...

Thanks for the article. I have a Marauder in 22 on the way and these reports of baffle clipping were one of my major concerns.

This blog is awesome. Thanks to all three of you guys and keep up the good work.

derrick38 said...

I think the baffle clipping issues have been resolved for several months now. If it is an issue on your rifle, it's a painless fix or Crosman will send you new baffles and a new end cap in a couple days. Let me know how you like the gun.

RickO'shea said...

Excellent tutorial. I am about to receive a Marauder next week and was wondering about how to clean it. I had searched both the Yellow Forum and the GTA and found advice that was good, but no real pics to help understand. You not only provided great textual information, but the step by step photos were most helpful. Thanks for taking the extra effort to be a worthwhile blog. You are now bookmarked on my computer

Sincerely, Rick O'shea

Anonymous said...

Hi !

Do you think a left handed bolt would be possible to fit into the Marauder ? Could the RH bolt be modfied or do you think a totally new LH bolt woulb be necessary ?

derrick38 said...

I think you'd need a new bolt and you'd need to mill the receiver, too. Try Greg Davis on the Yellow Airgun forum. He's done a couple lefty conversions.

Anonymous said...

thanks for the sharing pic.you have the step for making air gun step by step from trigger and air system running and locking ? hope can share to do the air gun at home

thanks you

Andrew Wise said...

Hi, i was wondering if you would please be able to share the dimensions of the baffles? just overall length please.
Thanks!