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Education / Training Gen 2 .25-caliber Benjamin Marauder: Part 3

Gen 2 .25-caliber Benjamin Marauder: Part 3

by Tom Gaylord
Writing as B.B. Pelletier

Benjamin Marauder air rifle Gen 2Second-generation Benjamin Marauder in a synthetic stock.

Part 1
Part 2
Part 4

This report covers:

  • RAI modular stock
  • The buttstock
  • Leapers
  • Rifle weight
  • Scope
  • Bipod and sling
  • 2015 Texas airgun show

Today, you’ll see the real reason I’m testing the .25-caliber Gen 2 Benjamin Marauder. I had not planned on this test at all! In fact, I found a high-end European air rifle at the SHOT Show that I planned to test for Shotgun News and my personal website. I tried to order that rifle, but it just never happened. So, when Dave Rensing of R. Arms Innovations (RAI) approached me with his modular stock at the Malvern airgun show, I decided to buy a Marauder and test it in a way I’ve never done before. This test will become part of a much larger feature article in Shotgun News this November, which is their full-color edition. If you can’t buy the magazine, don’t fret. It will also be posted on my website a few months after it’s published.

RAI modular stock

I chose the .25-caliber Marauder because of its Green Mountain barrel. It has a reputation for tack-driving accuracy that I’ve already caught glimpses of at the range. I won’t get into that today, as this report is about assembling the Gen 2 Marauder in the RAI modular stock with accessories from both RAI and Leapers. But, I will say that I collected some valuable data that will help me tune this rifle for optimum performance in the future.

Benjamin Marauder with accessories
The Gen 2 Marauder with the RAI modular stock (arrow) plus other RAI and Leapers accessories. When the boxes arrived, it felt like Christmas!

The modular stock looks small next to the original synthetic stock, and it is. But the modular stock is machined from aircraft aluminum, so it has the strength to accept all the accessories. It isn’t a whole stock at all. It’s just the forearm that accepts the action, and RAI calls it a chassis. It’s set up to accept an AR-15 style buttstock, and it gives you many options to choose from.

The AR-15 is the civilian version of the M16 battle rifle platform — the firearm equivalent of a Lego set. Modularity is one key feature of this platform, so the options you see here are but one set of possibilities for the Gen 2 Marauder.

Because there are so many options, you have to look at the modular stock as a base for building a rifle. I’ll talk you through my set of options and explain why I decided upon them. Dave sent the stock to me with an AR-15 triggerguard already attached, but this is the first part the buyer must choose. I found 7 variations to choose from on one popular firearms website, so this is your first choice.

Benjamin Marauder RAI modular stock
The RAI modular stock came with an oversized AR-15 triggerguard attached. This is a part the buyer must supply.

The buttstock

The main reason for taking on this project is the possibilities of different butts that I can select for my Marauder. Dave showed me a clever adapter at Malvern that allows the butt to swing to the left side of the rifle, thus significantly shortening the overall length of the gun. Dave makes this adapter, and it was a chief interest of mine for this project, so he supplied one.

Not only does the butt swing out of the way; but when it does, it opens a port for adjusting the striker spring tension with the butt attached. The factory stock also allows for this. But what the factory stock does not allow is adjustment of the air transfer port while the stock is installed. The RAI modular stock permits that adjustment at any time. This is a feature the public has begged for since the Marauder was launched. These 2 features allow the shooter to easily and quickly adjust both the velocity (air transfer port adjustment) and the reservoir fill pressure (striker spring tension).

Benjamin Marauder transfer port adjustments
The RAI modular stock has a cutout so you can adjust the air transfer port (arrow) without removing the action from the stock.

The swing butt adapter attaches to the modular stock, then the buffer tube screws into the other end. Obviously, the tube has no buffer spring installed (it isn’t needed). Fortunately, Leapers sells the tube by itself. I planned to install a UTG 6-position mil-spec adjustable butt, so I used their mil-spec buffer tube. Mil-spec buffer tubes are a different size than non-mil-spec tubes, so pay attention if you go this route.

Benjamin Marauder swing butt adaptor installed
The butt swing adapter attaches to the modular stock, then the buffer tube screws into it.


Leapers supplied a large number of parts for this project. The mil-spec buffer tube was screwed into the RAI swing adapter and locked in place with a castle nut. Then, the 6-position mil-spec extendable buttstock was slid onto the buffer tube. This completed the rifle’s butt, though RAI did supply another option.

If you don’t want the butt to swing to the side, there’s a separate RAI butt adapter that lets you adjust the butt for some different heights or for some cast-on and cast-off — depending on your desire. Then, you have a rigid butt that, once adjusted, fits you perfectly.

With the butt installed, the next step was to install the pistol grip. As with most of the parts, the modular stock accepts all AR-15 pistol grips, so I selected the UTG Sniper grip for my rifle. It has finger grooves and is made of a rough synthetic that’s grippy. It feels just right in my hand.

Rifle weight

The RAI modular stock is much smaller than the factory stock but doesn’t include things like the grip and the butt, plus the adapter and buffer tube for the butt. In factory trim, the Gen 2 Marauder in synthetic stock weighs 7.3 lbs. That’s before the scope is mounted. The rifle as modified for you today — again, minus the scope — weighs 9 lbs. The new forearm is much slimmer than even the forearm of the synthetic stock that was itself a great reduction in bulk from the original wood stock on the Gen 1 Marauder, but the combined parts are heavier.


I still have to add the scope, which is that new UTG 2-16X44AO Accushot scope I’ve been testing for you on the factory Gen 2 Marauder. I’m finding it to be everything I want in a scope for the field and an ideal match for this hunting rifle I’m building. With it mounted, the rifle weighs 10.5 lbs.

Blog reader Kevin asked me if the reticle lines in this scope are thin, and I told him they are. Last week, I discovered just how handy that illuminated reticle is. I lost the center of the reticle in the black bull at 50 yards because the day was overcast. So, I turned on the illuminated reticle and switched it so the lighted lines were faint. That made the crosshairs as thin as they could be, and I was able to bisect the center of the bull quite easily. It resulted in 6 shots from one pellet going into 0.417 inches and from another pellet into 0.552 inches at 50 yards. Without the ability to see the center of the reticle, both groups would have been larger.

Bipod and sling

Finally, we come to the bipod and sling — both Leapers UTG products. For hunting, the sling is essential for carrying the rifle. I have the UTG rifle sling. The bipod is less essential, but that will be dictated by how you hunt. I have a choice of 3 UTG bipods to choose from — the UTG rubber armored folding metal bipod you’ve already seen, a UTG tactical bipod that extends 6 to 8.5 inches and a UTG tactical bipod that pans (allows rotation of the rifle on the bipod). That’s a lot to test, and I plan on trying all of them.

It took me 45 minutes to install everything mentioned in this report. Nothing was difficult, but most things required some thought. The onboard pressure gauge is still visible on the bottom of the stock, and the rifle looks ready for the field. Better yet, it fits me quite well. I was concerned over losing the adjustable cheekpiece of the factory synthetic stock, but the straight line of the AR stock raises my sighting eye to the correct height. Had it not, I could have also installed the RAI adapter that allows for some movement of the butt and raised it that way.

Benjamin Marauder modified
The butt swing adapter attaches to the modular stock, then the buffer tube screws into it.

The cost?

I bet you’re interested in what this modification costs. I can’t possibly cost all the options for you because they largely depend on your personal tastes, but the bare RAI modular stock (they call it a chassis) retails for $309.99. The chassis with a rigid butt adapter, a 6-Position UTG mil-spec butt, an AR standard pistol grip and an AR oversized triggerguard retail for $447.99. The side-swing adapter costs $29.99. And, of course, you can order the parts from RAI and mix and match to your heart’s content.

The UTG parts to which I’ve linked have prices, so you have what you need there. And nothing stops you from selecting other AR-15 accessories in place of those I’ve shown.

Next, I’ll begin testing the modified rifle at the range. As mentioned earlier, I already know a couple things, so this test is well underway.

2015 Texas airgun show

The 2015 Texas airgun show is approaching fast! The show will be held on Saturday, August 29, and the reception will be the evening before. Don’t forget that you’ll get to watch a Round Table segment being filmed for the American Airgunner TV show at the reception. And, the film crew will be at the show all day.

Don’t miss the big bore match and be sure to participate in the action pistol and rifle matches we have planned for everyone. And, plan to buy some raffle tickets for the wonderful prizes that will be given out all day long. Your admission to the show also enters you in the door prize drawing at no extra charge.

If you want a table at the show, act now while they’re still available. I expect them to be gone before long. The information for tables, the motel and the reception is on the show flier.

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.

43 thoughts on “Gen 2 .25-caliber Benjamin Marauder: Part 3”

  1. Nice looking chassis, I have been looking at them on their site since you first mentioned them, and mulling it over and over, but solar, just have never pulled the trigger on the RAI system.

    While not too keen on the weight it adds back into the Marauder platform, it is a necessary evil if you want the modular system.

    The Kalamazoo MI. show is also coming up, I hope to make that one..
    Thanks for the review!
    Waiting to see how it all comes together..

  2. I was excited when Crosman announced the Armada, but my excitement waned when I got to handle one at the NRA show. Don’t get me wrong it was a nice gun, but the handguard seemed to want to move around a lot.

    The RAI stock appears to be a better solution albeit at a sizable expense and added weight.

    The big thing in this report that I’m looking forward to is the accuracy report on the gun with the Green Mountain barrel.

      • I’m tagging this irrelevant question on the end of this post as I’m not sure how to post a question to the blog. Call it newbie blues.

        Without going into a lot of background I’ve discovered air rifles recently both for squirrel control and for back yard target practice. I’ve torn down a Gamo “Whisper CFR” to install a CharlieDaTuna trigger. Tear down wasn’t bad – though I had to build a spring compressor.

        I’m now ready to tune the rifle and after reading thru a lot of old stuff here – somehow I started in maybe 05 and came forward – I’m not sure about some terms and lubricants. There is repeated mention of “tarring” the main spring. I’ve been in the trades 40+ years and am a master carpenter and builder. TAR goes on roofs, seals foundations, and is black sticky, thick, can only be thinned with paint thinner or gasoline. While I can immediately see the benefit in lubing the spring (this rifle is quite a twanger), I’m at a loss as to why tar would help. I’m guessing this is a “secret” term that has been used so often that people forget that newbies like myself don’t know what it is. Most of the other lubrication points are straight forward, but this one has me baffled. Enlightenment greatly appreciated

        • OntheRez,

          Welcome to the blog. This blog exists for people just like you.

          Before we talk about your rifle I would like you to look at the 10-part report I did recently on tuning the Diana 45.


          If you have read it, let me know and we can start from there.

          The tar is just a term I coined for a thick viscous grease that lubricates the coiled steel mainspring while dampening vibration. It works wonderfully, as you will see in the report of the Diana 45.

          Read that and then we will talk about your rifle and what must be done.


  3. That is a good look’n Marauder is all I can say.

    And I bet the way its equiped and the weight it did gain makes it set in position like a rock.

    I bet this gun will be very accurate just for the fact it should stay in place well.

      • BB
        You have any plans to take this out for a 100 yard accuracy test. Also are you by chance going to be able to shoot the new JSB 33.95 grain pellets for accuracy or are you not able to get them yet as I have some on preorder.

        I just acquired a 25 at a deal I could refuse and plan to tune it for long range shooting to have some fun at our FT club sight in range as last weekend I got to shoot a Rapid HM 1000x tuned and modified with a suppressor that made it the quietest air gun I have ever heard as you could be 20 feet from it and not hear it shoot. It would also ring the 100 yard spinner we have over and over with what seemed like you were shooting at 25 yards. It was shooting the JSB 25 grainers at 930 fps.

        I know the 25 Mrod can not compete with its shot count of 60 shot per fill since it is a regulated 500cc bottle but I do believe it can compete with the same accuracy at 100 yards. with hopefully at least 16 shot ( two magazines) or maybe even 20 shots at the tune I am doing to shoot 31 grain H&N barracudas at 900 plus fps and the new JSB 33.95 grain pellets as well.


          • BB
            Sound good and will be waiting to see your results as I was hoping you would stretch its legs,

            That Rapid I got to shoot was using the kings as well so it would be a good comparison to see if a 600 dollar gun can compete with a 2500 dollar custom made Rapid. As I said I am tuning my 25 to do just that as he said that a Mrod cannot get even close to the accuracy of his Rapid at 100 yards so I am planning to prove him wrong.

            He does have a very fine rifle in that rapid but just because it cost 5 times as much as a Mrod does not mean it is any more accurate. He is one of our WTFT shooters and is a very good shot but then when you have 3 Rapid , two 177s and the one 25 it does make it easier to shoot good .


  4. I really like the lines of the gun but it’s already too heavy for me to carry comfortably, if there were a simple conversion to a larger bore readily available it would make it a more difficult decision but I guess if I wind up with one I’ll be leaving it alone for a while.


  5. Another new gun to look at is a Sig Sauer MPX co2 rifle. I can get co2 a lot easier than HPA. If it could shoot 7.9 lead pellets at 750 FPS I would be interested but maybe that’s unrealistic for co2.

  6. I’m very impressed with the offerings from RAI. The modularity of this stock/chassis is almost overwhelming. If any airgun deserves this stock with these mods it’s the Marauder .25 caliber with the green mountain barrel.

    I’ve shot Erik’s quite a bit on several occasions and that gun is accurate. Not just accurate at a price point but I would put his gun up against any .25 caliber airgun platform.

    Don’t know if B.B.’s Marauder will outshoot his .22 caliber Talon ? at 100 yards but suspect it will give it a run for its’ money.

    I received the UTG 2-16X44 Accushot scope from Pyramyd AIR last week. Had a chance to mount it on a pcp, get it sighted in and mark yardages. Probably spent an hour with the scope. I’m impressed. It requires a very specific eye relief for focus. I like this since it aids me with a consistent cheek weld. Leapers has etched a decent reticle in this scope. Not to fine and not fat like may of their previous scopes I’ve owned. I had sun behind me when I was shooting and the glare was noticeable but not overly annoying. The coatings are good for a scope at this price point. It does well in dark shade. I put a sidewheel on mine and would strongly suggest it since the side AO needs fine adjusting for focus. I REALLY like the range of 2x-16x and the sidewheel AO. Perfect for my pesting needs. Even on 16x this scope is clear out to the edges. Wish they would put a locking ring on the ocular but it’s not a deal breaker for me. After I adjusted it I just put some electrical tape on it.

    PA had one of these scopes left I after I ordered mine. Hope they get more in stock because I think when the word gets out on this scope they’ll go quickly.


    • Kevin
      I don’t like the scopes without a locking ocular lens option, but I use o ring that I place in the groove once I get the ocular lens set where I want it I use two or three o rings to fill that gap and allow the lens to be snugged against the o rings to prevent accidental movement.


    • Kevin,

      Thanks for your report on the UTG scope. Not too fine and not too fat is a good description of the reticle lines. And I agree that at the price this is a very sharp scope.

      I am glad you like it.

      As for my new Marauder, I see the seeds of greatness in the gun. and not just for the money — at any price.

      We shall see.


  7. BB,

    Nice setup, I love to see how it handles and shoots. Can you also comment on the feel after you have shot it an entire day? Some rifles handle much better than others.

    As I see the layout of parts you used, I can not see where the difference in weight comes from. Can you weight the original stock and if it is still possible the parts which you used? There must be something out of the ordinary to get a difference of 1.7 lbs.



    • August,

      I will comment on how it handles.

      As for the weight, the adapter weighs about a half pound, the new metal modular stock weighs a couple pounds, the butt with extension tube weighs over a pound.

      The factory synthetic stock weighs 2.25 lbs, so it’s lighter than the modular stock chassis. And that is before adding the extendable butt, and the pistol grip.


  8. Off topic question for you BB and others. What bb gun (not pellet, but just bb gun) would you say would hold up the best under heavy use? By that I mean holds up shooting thousands and thousands of bbs? Daisy 499? Red Ryder? Model 25? Thank you.

    • Al,

      Welcome to the blog.

      I can actually answer that. In the 1960s and into the ’70s, the U.S. Army training centers used Daisy BB guns for their Quick Kill instinct training. Those guns had not thousands but millions of shots fired through them. They did have to replace firing plungers and shot tubes on some guns, but the guns lasted so well that they didn’t have to buy replacements.

      Those guns were very close to a Red Ryder in design. Not a Red Ryder of today, but one that was selling about 50 years ago.


  9. Al
    I have a Red Ryder that I have owned for 40 years and have no idea how many BBs it has shot but it is still shooting well today with just the occasional oiling and wipe down of the outside of the gun.

    I cannot comment on the others,


  10. I will also vouch for the durability of those old red ryders. Had one as a child that belonged to my grandfather when he was a child, I believe it would be early 40’s vintage, I must have shot tens of thousands of BBs through it and it still shoots today. I know it was well used, because it has numerous checks in the stock, one for every rabbit or pheasant they shot with it.

  11. BD I have a Red Ryder, still shooting my dad gave me when I was 6 years old that was 60 years ago. They are hard to put down. Plan to pass it on to grandchildren in the family.

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