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Ammo R.A.I. adjustable AR stock adapter: Part 2

R.A.I. adjustable AR stock adapter: Part 2

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

Part 1

Today, I’ll begin testing the R.A.I. AR adjustable stock adapter from rarmsinnovations.com with the UTG Pro 6-position adjustable stock attached to the Benjamin Marauder pistol.

Length of pull
Before we begin, I want to say a word about the length of pull you get with this adapter. I gave the range of lengths in Part 1 as 14-1/8 inches to 17-1/8 inches, and that turned off many readers. In terms of conventional stocks, that pull range is very long! But Dave Rensing, who invented this adapter, made it for his 8-year-old son and his 7-year-old daughter. The son uses it conventionally, but the daughter collapses the stock past the first detent so it’s even shorter. Fully collapsed, the pull length measures exactly 14 inches but feels like 11 inches.

The AR adjustable stock is not very ergonomic. It stretches and contracts okay, but it doesn’t move in the other directions. It’s a one-size fits none kind of deal — at least from a rifle marksmanship standpoint. While it works very well for fast maneuvering and climbing in and out of tight places, your body has to adapt a lot to make it work.

On the other hand, when the R.A.I. adapter is added to it, the stock becomes almost universal! You can adjust the positions of the comb and the angles of the buttstock through a wide range of attitudes and make it fit almost anyone — young or old. I found when shooting from the bench that even the 15-1/8-inch pull I had initially set up was too short. I had to move the stock back until the pull was 15-7/8-inches before it felt natural again. However, in the offhand position, the 15-1/8-inch pull is the right one. That demonstrates why the adjustable stock works so well on this pistol! You can adjust it to whatever you need in the blink of an eye.

I discovered why this is. The AR adjustable stock has no width. The narrow tube is where your cheek rests, so your eye is closer to the centerline of the pistol than it would be with a conventional stock. The stock also does not drop at the butt, so your head thrusts forward farther than it might with a conventional stock. Instead of sticking up to rest on the cheekpiece, your head tilts forward, along the straight tube. Hence, 14 inches feels more like 11 inches. The Marauder’s pistol grip and close trigger enhance this feeling.

Benjamin Marauder Pistol Tom holding offhand
Here I’m holding the carbine offhand. The pull seen here is 15-1/8 inches, and yet the rifle feels perfect. You can see that my head has gone forward on the stock because it’s so straight.

Scope and mounts
I wanted to test the pistol with a really good scope; and the last time I tested the Marauder  I used a CenterPoint 3-12X44 compact scope. Leapers was making CenterPoint scopes back then, so this time I attached a UTG 3-12X44 compact scope. My scope is older than the one I linked to, but the optics and overall size are the same. Not only does this scope fit the carbine very well, it gives a crystal clear sight picture that makes aiming so easy.

I needed to get the scope high off the receiver because the Marauder pistol has a circular 8-shot magazine that sticks up above the receiver top. You can see it in the above photo. Also, the stock’s straight line puts my head higher than it would normally be. So, high scope rings are in order. I selected a pair of BKL 30mm high rings that have a single-screw top strap. The Marauder pistol doesn’t recoil, so these rings can be made thinner and still be strong enough to hold this scope. Once they were mounted, I noted they brought the scope’s exit pupil directly to my eye, making them the perfect height.

Testing the Marauder carbine
I tested this Marauder pistol extensively, back in 2010/2011. I already knew the right fill pressure (2,900 psi), the best pellet (.22-caliber Beeman Kodiak) and the effective number of shots per fill (32). Since it has an 8-shot magazine, I shot 8-shot groups instead of 10.

Sight-in went quick, and then I backed up to 25 yards and started shooting. The first group of Kodiaks was the second-best of the session, putting 8 into 0.554 inches. Looking back at the tests I did years ago, I wasn’t shooting as well on this day as I did back then. I shot a total of six 8-shot groups, and the largest one was 0.607 inches, while the smallest was 0.504 inches between centers.

Benjamin Marauder Pistol first group
The first group was 8 Kodiaks into 0.554 inches at 25 yards.

Benjamin Marauder Pistol largest group
The worst group of the day was 8 Kodiaks in 0.607 inches at 25 yards.

Benjamin Marauder pistol smallest group
The best group of the day was 0.504-inches for 8 Kodiaks at 25 yards.

While these groups are okay, they aren’t as small as the groups I shot previously. I don’t think it was me or the gun. In this case, I think it was the pellet. I used a different tin of Kodiaks in 2010, and they grouped much tighter in this pistol than these did. The best group back then was 0.405 inches between centers. Maybe they had larger heads, or maybe they were just different in some unquantifiable way.

Other pellets
I tried a number of different pellets in the Marauder pistol, but none of them did very well. JSBs of various weights, which I thought would do well, sprayed all over the place. I know from testing the gun that it wants a fat pellet, and the Kodiak is a good one for that. It’s slow, at an average 584 f.p.s., but even at that it produces about 16 foot-pounds of muzzle energy. That’s pretty good for an air pistol! Certainly enough for some hunting and pest elimination.

The rest of the test
I plan to take this pistol to the 50-yard range, so you’ll see the results of that. But I don’t think that’s quite the right way to test the R.A.I. adapter and adjustable stock. We already know how well the pistol performs. Now, we want the focus to be on the adapter and the stock.

Maybe I can put the gun in the hands of some other shooters and see how well it fits them. Perhaps, that’s the best way to evaluate this item. I don’t know, but I guess we’ll see.

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.

32 thoughts on “R.A.I. adjustable AR stock adapter: Part 2”

  1. Hello B.B. and Fellow Airgunners
    I have not paid much attention to the Marauder pistol in the past. Because of it’s length and weight, I could not see it used as a pistol. It needed something something better then Crosman’s pistol stock to make it usable, and still look good. From the picture of you as you aim the gun, it looks like the R.A.I. adjustable stock, and the Marauder pistol were made for each other. With your claim of 32 usable shots, and the pictures of tight groups at 25 yards might make this combination my first PCP. Of coarse, the Marauder pistol is not for sale in Canada. However, the fact the Marauder rifle has just recently landed in our stores, and are selling like hotcakes, gives one reason for a dash of hope. Change is slow to come when it applies to firearms laws.
    Having other shooters at your range test this combination is a great idea. We all have differing body shapes and shooting styles, so it should show just how adjustable this stock is.

  2. BB,
    I think the best way for you to evaluate this setup is to send it to me. Seriously.

    Should I ever buy a “P-Rod”, the RAI adapter and an Airgun Lab double reservoir would be a must.

    • RR
      If you ain’t got one you should. I’m pretty sure you would like it.

      And I got a nice little trick to quiet down the Crosman/Benjamin Marauder style guns using the factory Marauder style shroud. And you don’t alter anything. All you do is add a spring and the gun is way quieter. ( and no you don’t even add steel wool or anything) Take the spring out and slide the shroud back and the gun is back to original.

      I showed Dave the trick when he was putting the adapter on my gun. I think he was surrprised how quiet the gun was.

      • It might happen, but I doubt it. I have the TSS carbine that I am building to fill that slot. Now if I could scrape up enough change, I would like to get an Edgun Leyla. I would also like something along the lines of a HW/Beeman R10 for when my grandson is a little older, but I do have an Edge that would probably work well for him. I would also like to build a Leige. Add to this my 1906 BSA and my Izzy, I will have pretty much all my shooting desires covered.

  3. My set up went a little differently then what BB’s set up is like.

    I already had my scope mounted and set on my .25 cal. Marauder rifle with the 1399 stock. I use short scope mounts on it. I don’t use the magazine. I use the single shot tray so I can get away with the shorter mounts.

    So basically after meeting with Dave and he set the adapter for me with his AR stock because I didn’t have mine yet. When I put my UTG AR stock on when I got it I didn’t remember what click of adjustment I had the length of pull set at. So I pulled the stock out to its longest length of pull. And put the gun up to my shoulder. I couldn’t see the sight picture in the scope. I had to go 3 clicks closer to shorten the length of pull.(and I have long arms) After that quick little adjustment I could put the gun to my shoulder and everytime have a perfect sight picture with my scope.

    I mounted the gun to my shoulder and unmounted then mounted it again multiple times and I was amazed at how fast I could now lock on to a target with my scoped gun. Yep fast acquisition with a scope. I like that. And whats nice is it just so happens that the stock is set in the middle of its adjustment. And I let both of my daughters try it with the stock adjusted at its shortest setting. They can sight the gun a lot better now. Before with the 1399 stock they had to hunch their self forward to pick up the sight picture. I guess the scope could of been moved back to help them out with the 1399 stock. But then the scope would need resighted and then my sight picture would be wrong. I would have to hold my head back to get the sight picture right for me.

    All I can say is my .25 cal. Marauder is a mean looking rifle now. If I took the Marauder script off of the receiver. And now with my barrel shroud slid forward 6″ and is fully floating with no barrel band
    clamp. I bet it would be hard for somebody to tell what kind of gun it is. They might even think it is some kind of tactical gun and be scared of it. Darn anyway I hate when that happens.

    Then hopefully Lloyd will have something worked up in the near future with a double air tube for the Marauder rifles. I know he will get a kit figured out for the normal stock. But I definitely would like to see what my Marauders going to look like with the extra tube added on to my setup.

    Well it looks like 2014 is turning out to have some innovative air gun ideas. All I can say is I’m excited. 🙂

  4. This looks like the gun I should have purchased! That is with this stock and adjuster. I have the old Marauder with the wood stock. It is amazingly accurate. I shoot tree rats in our back yard and even at around 60′ I can get head shots. Unfortunately, this gun is a bit too heavy, and I suppose I could have gotten a lighter scope. Since things are developing at Crosman, I’m waiting to see what comes next in the pistol. The new Marauder looks fantastic (with the plastic stock), but I just can’t keep buying the latest version. I’m watching, and I can’t wait to see the new developments in the pistol, which is what I should have waited for originally. I am sure Crosman is working on it, but are there any new developments you can hint at? 😎
    Michael in Georgia

    • Michael,

      I don’t know anything for sure, but I feel Crosman will give the $100 PCP some serious thought. They also have the MAR 177 that could be turned into a more powerful sporter or even a semiautomatic.

      There might be a fun new pistol coming next year. We will just have to wait and see.


  5. I shot Erik’s Marauder pistol quite a bit. We had to clean that factory barrel often to keep groups tight. He installed a lothar walther aftermarket barrel on that pistol and it didn’t improve the accuracy over the crosman barrel but it didn’t need to be cleaned often to maintain the accuracy.

    The addition of the RAI adjustable stock to the marauder pistol gives other carbines, like the ranchero, a run for their money at a fraction of the cost. It’s sure nice to have talented aftermarket modders bring these options to the market. Thanks RAI and Lloyd Sikes for creating options.


  6. Thanks for taking a closer look at the length of pull, B.B. It sounds like this could be a really nice solution for my seven- and ten-year-old boys (and their 41-year-old old man!).

    Better mail the thing to me so I can test quick changes between these different lengths of pull for you. I’ll have to hand onto it for a while, though, since the DIFTA range is currently closed due to snow!

    Since I’m too lazy to review Part 1, do I recall correctly that this adapter also works with the 1720T? And the Silhouette?

    PS, B.B., when you did your shooting for this report, how did you have the RAI adapter adjusted relative to the centerline? I can’t quite tell from the photos whether you have it off center and/or canted.


  7. The gun looks great with that stock, no rods here but they look a little front heavy? Did the stock improve balance in any way? I pretty much target shoot so the small game don’t suffer… Love carbines, Ill buy lower priced Chinese rifles and cut em down every time, see which ones work. Saving for a beeman R11, don’t think I’ll be cutting anything on that though! My next will be a 34p compact

  8. I have the adapter on my marauder pistol along with an ATI adjustable stock, UTG 10/22 commando rail system, angled foregrip, AR style UTG iron sights (no scope), and a sling. It weighs about 5.5lbs but can get a little heavy when shooting offhand for loong periods (which is all I do with this gun). The sling enables crazy tight groups. This is probably my favorite gun to shoot, and I have many…and many more expensive at that!

  9. I should think that a valuable test of this adapter would be to have a number of different sized people use it,, off hand. When shooting benched,, small accommodations to misfitted stocks may not be as noticeable. Offhand, the small variances will be multiplied, and much easier to see. In some of the matches I shoot, I have noticed a number of other shooters spending more time making the adjustments to their stocks than to shoot the 20 plus sighters needed. Even at these levels, the small things tend to grow large.

  10. BB,
    Thanks for putting that picture of you shouldering the gun for firing. I can now see how the conventional Length of Pull rules go out the window.
    It also makes it VERY easy to see how you used the adjustability in the RAI adapter to drop the butt stock almost an inch lower than where a plain straight-thru adapter would have put it. It all seems to work as a nice ergonomic package.

  11. Shot the.25 cal. Marauder today with the R.A.I. adapter and UTG AR butt stock. All I can say is amazing.

    Its like the gun locks into a hold the same everytime I put it to my shoulder to shoot. And my groups were more consistent. Was going to let my daughters try it to see how the a adjustable length of pull worked out for them but they are both sick right now along with my wife with that coughing headache thing going around. Hopefully they will be better before the weekend and they can give it a try.

  12. Hi there.
    I try to go to the RAI website and it doesnt work.
    do you have any idea if this person is still selling this adapter? O maybe another way to contact him?

  13. The website was in the process of being upgraded and we had some unexpected issues. We have everything working now with some new additions also. Thank You all for your patience.

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