R.A.I. adjustable AR stock adapter: Part 2
by Tom Gaylord, a.k.a. B.B. Pelletier
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.
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.
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.
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.