R.A.I. adjustable AR stock adapter: Part 1
by Tom Gaylord, a.k.a. B.B. Pelletier
Wives, I want to warn you — today, I’m going to be The Great Enabler! Last year, I was sent a product to test for Pyramyd Air — an AR stock adapter for certain Crosman pistols by R.A.I. It lets you turn a pistol like the Benjamin Marauder into a carbine by adding an M4 telescoping stock to the back of the gun.
But why would you want to do that? Well, Dave Rensing, the owner of R. Arms Innovations — rarmsinnovations.com — wanted to do it so his young son could shoot his Marauder pistol. The big pistol is heavy for a youngster, especially when it has a scope mounted; but with an adjustable carbine stock, the youngster can size it to fit and then rest it on any convenient place and shoot it like a rifle. And because the M4 stock adjusts for length of pull, Dave can adjust it for himself in seconds. If 2 or more people can shoot the same airgun, the $400 price tag gets spread around and diluted.
The Marauder pistol does come with a factory shoulder stock that turns it into a carbine, so what does this adapter do that the factory stock doesn’t? It all comes down to adjustability. The R.A.I. adapter allows the adjustment of the stock to a wide range of positions that should fit most shooters. Not only is the pull length adjustable because of the M4 extendable stock, you can also raise and lower the stock line (the amount of comb drop), which affects the height of the butt; and you can have a wide range of cast-off and cast-on stock positions (where the stock angles away from you or toward you). And it doesn’t end there. You can also rotate the angle of the butt from straight up and down to where the toe is slanted in toward you or out, away from you.
The R.A.I. adapter helps make the Marauder pistol (and some others others I’ll mention later) into a small carbine that fits the shooter. And let’s not forget that it attaches to a telescoping M4 stock. What that does will differ with each brand; but for this test, I’m mounting a UTG PRO 6-position mil-spec stock assembly that has 6 different lengths of pull. On my test pistol, the length of pull runs from 14-1/8 inches to 17-1/8 inches. This is a rare occasion where I find the length of pull is adjustable to my liking!
The R.A.I adapter
The R.A.I. adapter is made in 3 pieces. Two are machined aluminum, and the third is the bolt that holds everything together, plus attaching it to the gun.
The R.A.I. adapter consists of these 3 parts.
This view reveals the essence of the R.A.I. design. That elongated hole, which can be positioned at any angle around a full circle, allows the smaller piece to slide out to the edge of the larger piece.
The bolt fits through both machined pieces and threads into the hole at the back of the Marauder.
Here, the adapter is installed. The bolt runs through both machined pieces and fastens them to the pistol. The smaller piece fits over the Marauder end cap.
That elongated hole in the large piece allows the adapter to be rotated up.
Here the adapter is shown rotated down. It can be rotated to any position around a full circle!
Now that you understand how the adapter works, let’s look at the stock that attaches to it. I used a UTG PRO mil-spec stock assembly that has 6 positions for length. The mil-spec designation means the stock tube size conforms to military drawings.
This stock comes from Leapers as a complete package that’s ready to install. The buffer and buffer spring are shipped inside the stock but are not needed for the airgun application. The flange that locks the stock to the AR receiver to prevent it from rotating on the firearm can also be removed.
When the stock is screwed into the adapter, the castellated locknut that tightens the stock can be used to lock it in any orientation you want. Regardless of how the adapter is positioned, the stock can be snugged down. This makes the R.A.I. adapter a very adjustable item!
This castellated locknut allows you to lock the stock in any position. The adapter can be rotated however it suits you, and the stock can then be locked to it in any position.
I found this adjustability to be a blessing! As I’ve mentioned more than once, I usually have to adapt to the rifle I’m testing because not many rifles adjust. Most stocks are too short for me, and most combs are too low. I’ve learned to put up with just about anything to get the job done, but it’s rare that I get to shoot a rifle that actually fits me. This R.A.I. adapter may change that with the Marauder pistol.
I’ve now adjusted the stock so the gun comes up fast and feels fine against my shoulder. I won’t know for sure if I have it adjusted right until I shoot the carbine several times — so guess what’s coming?
With the stock mounted, I find that I can position it exactly as I like it. This might work!
I was surprised to find that the stock’s pull was 15-1/8 inches when I had it adjusted the way I like. I always knew that I liked a longer pull, but this was even longer than I’d suspected.
I also have the comb’s drop set at the maximum; but since this is a straight-line stock, it’s perfect. The cast is set straight for me. And I have the toe of the butt canted into my collarbone. It will require some shooting to establish if this is the best fit for me, but right now it feels good.
What else will it fit?
Besides the Benjamin Marauder this adapter also fits the Crosman Silhouette pistol, the Crosman 1720T PCP Target air pistol, and the Benjamin Marauder Woods Walker. These PCP pistols are all expensive, so the R.A.I. adapter offers a way to expand the utility of each of them across a wide spectrum of shooters.
Is it worth it?
The R.A.I. adapter costs extra, and so does any extendable AR stock you’ll need to purchase with it. The Marauder already comes with a shoulder stock, so is this setup worth the extra expense? It is if you want your carbine to fit a lot of different shooters. If you want to share your carbine with your wife or your children, then this adapter makes that possible, with the gun adjusting to fit everyone. It’s also something to consider if the regular stocks don’t fit too well. I can’t say this one is universal, but it does cover a pretty wide ranges of needs.
This accessory is unlike what I usually test. I’ll be shooting the Marauder pistol to see if I like how the stock makes it shoot for me. That’s a little different than my normal type of test, but I think it should be very interesting and perhaps even informative. Stick around — there’s more to come!