Gun Review: JR Carbine


JR stands for Just Right. And boy did I want this pistol caliber carbine to be JR. I wanted so badly for it to be JR. But it wasn’t JR. It was really only POK (pretty OK). But POK Carbine doesn’t roll off the tongue quite like JR Carbine. The JR may not be quite right, but it’s totally salvageable. With some work, I think the boys from Canandaigua could have a truly awesome gun on their hands. Sticking to our newly debuted review guidelines, I’m going to build it up and tear it down . . .


If you are a regular reader, the JR should be stirring a bit of déjà vu in your brain space. Our man Dan did a preview back in December that never made like Red Bull and got wings. Turns out that running the operations of the most popular gun blog in the universe eats into your range time.

So Dan the Man called me up and asked if I’d be willing to give it a go. He had already put a few hundred (or maybe thousand) rounds down the tube, and left it dirty. Without realizing it, Dan had set something in motion and found a platform for me that I needed without knowing that I needed it. A pistol caliber carbine? Genius! A pistol caliber carbine that uses AR furniture and Glock mags? Bloody brilliant!

In its cold, black heart, the JR carbine is a pistol caliber (9mm for this test) carbine loosely built on the general design of the very popular AR platform. However, the JR shucked the gas impingement system for a much more simple blowback design. This allowed the guys at JR to give the gun ambidextrous bolt and ejection options.

In addition, you can swap out barrels and bolt assemblies to switch calibers. And looking at the product specs, you can tell the designers were bitten hard at some point by somebody using proprietary technology. Users can deploy standard AR furniture and trigger components… all while using Glock or 1911 mags. Add that to the threaded barrel that’s suppressor-ready and you have a platform that will actually complement your collection instead of adding another dimension of accessories and headaches.

Overall Appearance & Fit/Finish 

The JR is obviously built to a very high standard. I was hard pressed to find any machine marks, defects or mis-alignments in the entire platform. The barrel and receiver finishes were defect free and managed to handle being thrown around the truck without too much fuss. The top rail happily accepted an EOTech sight and the whole rig is without rattles or any of that “cheap” feeling that can sometimes come from new-to-the-market manufacturers.

I’m giving four stars because the bolt internals aren’t chromed and started to look a little dingy as time and cheap 9mm ammo took their toll. Another small item is the use of Phillips head screws on the ejection port blockoff plate. Seriously? Phillips button head screws? Those need to be upgraded to Allen heads ASAP. As you can tell, I’m really looking for things to ding the JR on here.

Ease of Use 

I giggled at the bolt lock system when I first saw it because for the first time I’d be able to do that cool bolt-catch slap thing every B movie actor does while running an MP5. Then I shot my first mag and realized that the bolt doesn’t hold open when done. I realize we’re not tacticool mall ninjas. I get that. Really. But I don’t think it’s too much to ask to have the bolt lock open when a mag’s empty.

I think this is a practical limitation stemming from the fact that the JR was designed to use a few different magazines to achieve compatibility. Even if the JR was standardized on the Glock mags, I doubt it would have the bolt hold open as that would add manufacturing complexity (read: cost) to the design.

The second nit that needs picking is the magazine release. For those familiar with the AR platform, you are going to be sorely disappointed when you try to use your right index finger to drop a mag. No such button exists over there. The mag release is over on the left hand side of the interchangeable magazine well. For us righties, it isn’t the end of the world, but it does mean that quick mag changes aren’t happening. For southpaws, this problem is only amplified as you’ll have to hold the rifle against your shoulder with your support hand and manipulate the magazine release.

In a perfect world, this gun has a bolt hold-open and a much better control layout. But we don’t live in a perfect world, bummer though that may be. In the video above, I bitch about how the Glock mags won’t drop free. I don’t believe this to be JR’s fault. I’m blaming the plastic magazines and a very dirty gun.

Ease of Disassembly 

In a word, nope. Not easy at all. Pistol ammo is gross. I rank it right up there with .22 LR for dirtying up a fine firearm lickety split. Especially steel-cased TulAmmo. Keep in mind that I got the gun dirty and continued to run it that way. So when I finally did clean it up in anticipation of its eventual return, I was shocked to discover how involved the field stripping process was.

First, you have to remove the shoulder thing that goes up, and then remove three Allen screws to separate the upper from the lower. At that point the bolt, buffer and spring fall out. If you are truly serious about cleaning, you’ll remove those aforementioned Phillips screws on the ejection port cover and scrub everything down. And you’ll need to. The JR will get dirty.

This disassembly process is a little worrisome. From a metallurgy standpoint, using finely threaded Allen screws in an application like retention of the upper has potential for heartache. If you don’t ever clean your gun, disregard this portion of the review.

I’m a neat freak when it comes to my guns. That means I’d be disassembling the upper and lower after every range session and at some point, I’d wear out the threads on those screws (best case) or on the lower (worst case). Not to mention the fact that you have to unscrew the buffer tube for every field strip. JR 2.0 needs to incorporate the pin system that ARs use for long-term reliability.

Handling Characteristics 

At 6.5 lbs stripped, the JR is on par with a standard M4 style AR-15. It’s very well balanced and handles like any similarly equipped AR. Other than the aforementioned bolt handle and mag release issues, the ergonomics are very good. The six-position stock will allow you to adjust length of pull to fit smaller shooters or shoot with bulky clothing or armor. The JR is not supplied with sights, but has plenty of rail space to accommodate irons, red dots, and magnifiers.

The trigger is typical milspec. It breaks consistently at 6.5 lbs, but the road to get there is fraught with false breaks and some grit. You can actually see in the video where I let out a little “whoop!” before the shooting starts. I found the first false break and jerked one off to the side. After a thorough cleaning, things got a little better, but if you are considering a JR, consider a trigger kit to match. From what I can glean, the JR will accept standard AR triggers. My Timney is married to my AR so I didn’t test JR’s claim.


What you see here is a five shot group from 50 yards off a solid rest using an EOTech red dot sight. Keep in mind that at the time, the JR was hot, dirty and flinging TulAmmo. So what you see is literally the worst possible scenario for accuracy. My best group managed a maximum spread of two inches. That’s easily within the realm of reason for what this gun is. Better ammo, a clean gun and magnified optics could easily help that number drop closer to one inch.


I had absolutely zero issues with reliability using the cheapest ammo possible in arguably the dirtiest gun I’ve ever received for T&E.

Applicability for a Given Situation 

This gun would be perfect as a casual plinking gun for those not in love with dropping 5.56 money to shoot at 50 yards or less. For those with Glocks galore, you’ll love the fact that you can use those magazines in the JR. And with a suppressor attached, this would make an excellent platform for teaching new shooters as the muzzle report and recoil are pretty negligible. This gun would also be awfully comfortable as a home defense or trunk/bug out gun.

Available Aftermarket Options 

The JR takes AR furniture, Glock magazines and has a gang of 1913 rail space. There’s not much you can’t mount to this gun if you want to. And with the proliferation of 30+ round Glock mags, you can feed the JR with relative ease. Add that to the ludicrously inexpensive ($279) conversion kits to take your JR to another caliber, and you have the makings of an uber-modular gun.

Favorite Feature

It shoots 9mm! How cool is that? Honestly, the ability to take AR parts and Glock mags is absolutely awesome.

Least Favorite Feature

It’s a tie between the lack of bolt hold open and the location of the mag release.

Specifications: JR Carbine

  •  Semi-automatic pistol-caliber carbine
  • Ambidextrous bolt – configurable for left or right-hand ejection
  • Converts to other pistol-calibers
  • Magazine included – Glock or 1911 depending on model
  • 16-1/4″ barrel
  • Free-floating quadrail forend
  • Picatinny rail machined into top of receiver
  • Telescoping 6-position collapsible M-4 style buttstock
  • Utilizes standard M-4/AR-15 furniture and trigger components
  • Weight: 6.5 lbs.
  • Overall length: buttstock extended 33-1/2″, collapsed 30-1/4″
  • Made in the USA
  • Price: $500-$700 on the open market

Overall Appearance, Fit and Finish * * * *

The build quality here is excellent and shows the mark of some true craftsmen. However, I’d like to see a bit more work on the internals to resist dirty 9 mm ammo. Additionally, standardization on one type and size of screw would be welcome. Phillips screws are for decking.

Ease of Use * * *

That lack of bolt hold open and easily accessible magazine release mean that this gun is forever relegated to plinking range toy duty instead of a competition gun or even home defense weapon. Even though the controls aren’t laid out nicely, though, they do work well.

Ease of Disassembly * *

Easily, the worst aspect of this gun is breaking it down for cleaning. Field stripping requires the removal of the entire buttstock and the lower is held to the upper with three finely threaded Allen screws. In my opinion, this is a recipe for disaster.

Handling * * *

From a comfort standpoint, the JR is quite nice. I have small hands so the front handguard was a touch too big for me. The three star rating comes from the rough and gritty trigger. After some cleaning it got less gritty, but it’s still pretty bad. Definitely consider upgrading this if you are buying one.

Accuracy * * * *

I was pleasantly surprised by the accuracy I saw out of the JR. I consider our test conditions to be the least ideal for getting a good feel for accuracy. We shot the JR hot, dirty, used cheap ammo and without a magnified optic. All that, and it still managed a 5 shot grouping with a 2 inch max spread. Sub inch and it would have gotten 5 stars. I’m mean like that.

Reliability * * * * 

I had zero issues, but did not get the opportunity to burn thousands of rounds so I’ll go with a conservative 4 star rating.

Available Aftermarket Options * * * * *

The JR is standardized on two of the most popular gun platforms around, the AR and Glock pistols. Between the two, you should be able to customize the JR to your heart’s desire. Add the ability to convert calibers for less than $300 and you have a five star winner on your hands.

Final Thoughts * * *
The JR Carbine fills a niche. If you get the chance to shoot a pistol caliber carbine, you’ll see why. They’re light, fun to shoot, inexpensive to operate and in the case of the JR, compatible with a lot of other guns and accessories you likely already own. That said, my opinion is that the JR is not quite JR as it stands today.
Two design changes need to happen. First, the they need to do away with the threaded pin system for attaching the upper and lower. This won’t stand up to frequent cleaning as the pinned AR lower style system will. Second, they need to chuck the modular magazine well and standardize on Glock magazines. This will allow them (hopefully) to relocate the magazine release to a better position so the gun will have a manual of arms similar to America’s favorite modern sporting rifle.
As I said in the beginning, the JR Carbine has the potential to be absolutely badass. Maybe they have to bite the bullet and use a stock AR lower instead of their homebrewed design. That sucks, I’m sure, but as a buyer (and reviewer), having the buttons in all the right places with a proven structural design gives me the comfort to plunk down a fairly reasonable sum of money and put one of these in my safe.