Powder River Rimfire
Assembling PRP’s Rubicon .22 LR
Powder River Precision’s machined rimfire receiver, assembled with a Hogue Stock and Briley barrel,
is a high-performance, lightweight package weighing around 4 lbs., with no mag or optic.
The starting point: Powder River Precision’s Rubicon .22 receiver,
Hogue over-molded stock, Briley lightweight barrel and PRP lockwork.
A gun is a “standard” when you can build one using parts made entirely by people other than the original manufacturer. The 1911, AR, GLOCK and others come immediately to mind, as well as Ruger’s MkIV and 10/22. And make no mistake, the Ruger .22s are the standard. Since its introduction nearly 60 years ago, the 10/22 has been the first gun for generations of boys (myself included) and served in cloak-and-dagger applications here and overseas. It does all of this well enough to have earned a strong aftermarket, including custom receivers.
The tools: punch set from PRP, blue threadlocker, torque wrench
and barrel wedge tool and Brownells screwdriver. Jeremy prefers
the short-handled screwdriver because it seems to give better control.
Machined from 6061 aluminum barstock, the Rubicon receiver
is standard in anodized black. It has an integral Picatinny rail
cleaning-rod hole and has been designed to accept a more
efficient centrally located recoil spring.
The sleek receiver profile of the Ruger 10/22 leaves no room for
a recoil spring above the bolt, requiring that it be offset to the side of the bolt.
The extra room afforded by the Picatinny rail allows PRP to use a
centrally located recoil spring, which is more mechanically efficient
and removes the risk of bolt cant.
PRP’s bolt is machined from 416 stainless barstock and through-hardened.
Barrel installed, showing where the bolt makes contact with
the rear of the breechface — hence the importance of that
steel barrel shank.
Rubicon Receiver
Those who tinker with Springfield’s popular XD are already familiar with Powder River Precision (PRP). Owner Daniel Batchelor, current president of the American Pistolsmith’s Guild, was an early adopter and manufactures a variety of popular XD parts. Having turned his eye to rimfire rifles, the newly introduced Rubicon will also look familiar.
While a small number of complete rifles may be on the horizon, the trademarked Rubicon is now available as a .22 LR receiver incorporating custom features such as a cleaning-rod hole in the rear of the receiver (you clean a rifle from breech to muzzle, the same direction the bullet goes), as well as an integral Picatinny rail — and herein lies a story.
The 10/22 has a low, rounded receiver top that helps create the overall sleek look of the rifle and gives good sightlines for the barrel-mounted irons. This low receiver also means the recoil spring and guide rod are mounted to one side of the factory bolt. While a recoil spring directly in line with the force of the breechface is more mechanically efficient, the 10/22’s firing pin passes through the middle of the bolt, leaving little room for a spring. A centrally mounted spring would have to go above the bolt, requiring more vertical room than is available. The Rubicon’s integral rail creates enough room for a centrally mounted recoil spring, reducing the friction from having an offset recoil spring and eliminating any possibility of the bolt canting.
Machined from 6061 aluminum barstock, the Rubicon is standard in anodized black. This one arrived at the FFL with PRP’s bolt, machined from 416 stainless barstock and through-hardened. It has a round firing pin rather than the customary flat one (a change Walther also made in its P38, for those who follow such things), and the length has been carefully engineered to avoid striking the rear of the chamber if the gun is dry-fired — a hereditary problem affecting all rimfires.
PRP’s Delta extractor kit comes with three extractors, each
with different size hooks for tuning individual guns. They fit 10/22s
and Mk-series pistols as well as clones. The extractors push out
easily with a thumbnail, and the hook serves as a disassembly tool.
The barrel wedge fits into an angled slot on the barrel, clamping it into the receiver.
The PRP wedge is made of aluminum rather than steel to avoid marring the receiver or aftermarket aluminum
barrels and comes marked with the correct orientation and torque value.
Internal Extras
The bolt comes assembled with PRP’s precision extractor. Cut by wire EDM rather than the more common stamping, the extractor (like all the other parts) is intended to be interchangeable with other manufacturers’ rifles, as well as Ruger Mk-series pistols and clones. There’s also a Delta kit available with three different sized extractors for tuning your gun, as well as integral disassembly tool. Hold that thought; we’ll see this extractor again.
The receiver also came accompanied by PRP’s 6061 aluminum barrel wedge, intended to avoid the risk of a steel block distorting the aluminum receiver and the corresponding locking cut in today’s aftermarket barrels, which are also often made of aluminum. The wedge comes with two installed steel washers and is marked with its 23 inch-pounds torque value and an arrow helpfully pointing “up.”
Unlike other lined aluminum barrels, the Briley Raptor’s barrel shank and ½x28 muzzle threads are made of stainless steel to withstand
the constant impact of the steel bolt and protect from deformation with the expected suppressor use.
The flutes on Briley’s 16.5" Raptor barrel keep it stiff and help aid
cooling while still being lightweight. The lined aluminum barrel
weighs over a pound less than the factory tapered barrel.
Briley Barrel
I used a 16.5″ Raptor barrel supplied by Briley that weighs over a pound less than the factory-tapered barrel. Like other aluminum barrels, it has a rifled steel liner. Unlike some others, the barrel shank and ½x28 muzzle threads are made of stainless steel, which helps the breech withstand the constant impact of the steel bolt and protect the muzzle threads from deformation with the expected suppressor use. Even so, it comes with a knurled thread protector. Both tapered and fluted, it is shockingly light, helpful for speed shooting (heavier rifles take longer to pivot) and for younger shooters.
The stock, a Hogue over-molded one in black to match the overall subdued appearance of the finished rifle, is similarly light while still retaining the “big gun” feel of the 10/22 that distinguishes it from the smaller dimensions of many rimfire rifles.
PRP’s glass-filled nylon trigger housing comes with machined
aluminum and stainless parts including wire EDM’d lockwork.
Spring assembly seated correctly in its slot before inserting the bolt.
Once the bolt is in and able to move freely, insert the buffer
that limits rearward bolt travel so it can’t come out while cycling.
PRP’s buffer is a stainless steel pin inserted in elastomer tubing
that cushions the impact on the receiver and reduces action noise,
important for those running suppressors.
PRP Trigger
Powder River has long been known for its trigger components, so I was not surprised to receive an assembled trigger housing. Molded from glass-filled nylon, the housing is packed with machined aluminum and stainless parts from PRP, including wire EDM’d lockwork designed to deliver a crisp trigger pull in the 2.5-lb. range. This one averaged 1 lb., 12.5 oz. on my Lyman digital scale, but the flat trigger face could have affected this reading.
Hogue supplied its overmolded stock for this build. Lightweight
but still retaining the traditional “big gun” feel of the 10/22, the
grippy texture and mild palmswell make it very comfortable to handle.
Neither the Briley barrel nor Hogue stock has any provision for a
barrel band. The two are held together with this takedown screw,
which is the only Ruger part in the gun. Make it snug, but don’t clamp it to death.
PRP offers an auto-release bolt latch and ejector with a spare extractor built into the part for emergency field repairs.
Bolt Latch & Mag Release
The bolt latch has a spare extractor designed into it. It can be punched out when needed, a patented feature (there’s also an ejector available separately that incorporates a spare extractor). While PRP didn’t design the auto-release bolt latch, it’s still a nice feature for those who remember fumbling around on the stock latch trying to find the right side of the rocker motion. While the latch still has to be manually activated, just pull the bolt handle back to release it.
The extended magazine release, which is intended to be operated with the shooting hand, can also be activated like the original flat 10/22 mag release and has a helpful scallop to give ready access to the bolt release. While the curvature of the trigger guard is a little different than the stock one, the mag release will also work on a factory trigger housing. Fully assembled, the trigger housing weighs 4.5 oz., about two less than the metal one on my 30-year-old 10/22, and which has since been replaced on Ruger rifles by a polymer one.
If you think these all sound like premium components, you are correct. While they can all be used separately to enhance other factory rifles, the Rubicon is not intended as a 1:1 competitor for factory Rugers, but a high-end precision tool for demanding applications. As they say about cars, speed costs money, and this is a gun for people who want to go fast.
The spring assembly fits into its obvious slot, at the rear of which
is a divot into which the base of the recoil spring guide rod sits.
This view shows the rear of the receiver. Note cleaning-rod hole.
Taking care not to let the recoil spring guide rod come out of its divot, draw the cocking handle back against spring pressure and hold it.
With the charging handle held back, the bolt can be inserted at the
rear of the receiver and pushed down until the bolt handle mates with
its slot across the top of the bolt. Once it’s seated all the way, the bolt
will be able to move forward and engage the guide rails on which it travels.
Here, the charging handle is only partially in its slot in the bolt.
Bolt Assembly
For those who haven’t been inside a 10/22, assembling the gun with completed sub-assemblies is fairly straightforward.
Start by inserting the recoil spring/cocking handle assembly through the ejection port of the upside-down receiver. The spring assembly will fit into its obvious slot, at the rear of which is a divot into which the base of the recoil spring guide rod sits. With the rod buttressed against its divot, pull the charging handle back against spring pressure and hold it there. The bolt can be inserted at the rear of the receiver through clearance cuts in its guide rails that hold it in place when it is forward. As the bolt drops down into position, line up the bolt handle with the slot cut across the front of the bolt and push it down until it mates. This is one of the fiddly bits, so it may take a couple of times.
Once the bolt is in and can move freely backward and forward, insert the bolt buffer that limits the bolt’s rearward travel so it can’t come out while cycling. I used the PRP buffer, a stainless-steel pin inserted in elastomer tubing. In addition to cushioning the impact on the receiver, it reduces action noise, which is important for those running suppressors. I first saw something similar over 20 years ago on an integrally suppressed prototype rifle built for an alphabet agency.
Once the bolt is installed, check the orientation of the extractor
to make sure it lines up with the extractor recess in the barrel
before barrel installation.
Align the barrel so its locking slot lines up with the matching
cut in the receiver so the barrel wedge will bear equally on
both parts. When it does (assuming the extractor still clears),
line up the wedge.
Don’t forget to put blue threadlocker on the barrel wedge screws.
Torquing the screws requires a tool with three things: a ball
hex head that can tighten the screws at an angle; a long enough
shaft for the head of the torque wrench to clear the barrel; and
an interface that will fit the ¼" drive on an inch-pound torque wrench.
Barrel Installation
Next comes the barrel. First, check to make sure there’s no interference between the extractor and its clearance cut on the barrel shank (hence why the bolt went in first), then align the barrel so its locking slot lines up with the matching cut in the receiver. When it does (assuming the extractor still clears), line up the barrel wedge that will lock it in place. I chose to put a bit of blue threadlocker on the threads of both screws before I installed them: I’ve not shot one loose, but it never hurts.
Torquing is the fun part since it’s challenging to reach the screws with a torque wrench. This means you need a tool with three things: a ball hex head that can tighten the screws at an angle; a long enough shaft for the head of the torque wrench to clear the barrel; and an interface that will fit a ¼” drive, which is what my inch-pound torque wrench uses.
Unable to find anything at the local hardware or auto-parts store, I bought a set of ball-end hex keys and sacrificed the 4mm one that fit the screw heads by cutting it to give me a long shaft, which I then inserted into a 4mm ¼” drive socket (thanks, Autozone!) and glued lightly in place with threadlocker. The threadlocker may not last forever, but it will at least keep those two pieces together in my toolbox. With the vernier scale on my torque wrench set to 23, I slowly tightened each screw alternately until the wrench clicked, and I was done.
Options include flat aluminum triggers in red or black and
machined aluminum mag releases in the same colors
and red cocking handles.
Part of the magic in the PRP trigger is the ball bearing
trigger reset system. You do not wanna get inside of this:
Buy it with the trigger you want already installed and leave it alone.
Trigger-Housing Installation
If you buy the trigger housing fully assembled (which is how it comes), installing it requires only pushing in the two receiver cross pins holding it in place. I used the two precision ground stainless pins from PRP, which are slightly oversized (0.0015″) for a tighter fit. If you are swapping parts on a factory housing, such as the bolt catch or mag release, you’ll need a pin punch. Start with the pin nearest the top of the housing, work your way down and be careful. The PRP housing comes with a curved polymer trigger, with optional straight aluminum triggers in red or black. Word to the wise: These should be ordered as options with the housing, not swapped later. Part of the magic in the PRP trigger pull is a pair of ball bearings in the reset spring assembly, and you do not wanna get sideways with those. They’ll launch into orbit by the time you know they’re there, much less getting them back in place for reassembly. Best to only swap parts in the top half of the housing.
The Hogue stock has raised contact pads that may need to
be filed or sanded for a proper fit, but no adjustment was needed on this gun.
Before installing the barreled action in the stock, push the
safety plunger to a halfway position; otherwise, it won’t clear
the stock. Then insert the rear of the receiver down into the
stock and rotate the barrel down into its channel.
Receiver to Stock
Once the trigger housing is in place, move the safety plunger to a halfway position (otherwise, it won’t clear the stock) and insert the rear of the receiver down into the stock. Once it’s seated, rotate the barrel down into its channel. The Hogue stock has raised contact pads that may need to be filed or sanded for a proper fit, but this gun needed no adjustment. Screw it all together with the takedown screw (the only factory Ruger part in the gun), and it’s time for the optic.
Vortex’s lightweight Sparc Solar came with two 2032 batteries,
an optional mount that adds 18mm in height and a handy tool
for mounting and zeroing.
Vortex
At Batchelor’s recommendation, I reached out to Vortex. They sent a Sparc Solar red dot for the finished rifle. Tipping the scales less than 4 oz., it fits with the leitmotif of the rifle (pun intended), which, with no optic or magazine, weighs 4 lbs. The Sparc and a Ruger 15-rounder add 11.5 oz. The Sparc has a 2 MOA dot with 12 brightness settings and both auto-off and “shake awake” features. Powered by a single 2032 battery (it came with two), it also has an auxiliary solar panel to reduce draw from the battery, which is advertised to last 150,000+ hours when the two are combined. At its best, you’d be changing batteries in 2039, but more regularly is probably wise. And the battery housing is a handy place to slip one of the rubber lens covers to keep it out of the field of view.
This rifle is going to spend a lot of time being shot …
For more info:
PowderRiverPrecision.com
Briley.com
Brownells.com
HogueInc.com
VortexOptics.com
