A Dedicated 9mm AR-15
There are 9mm conversion kits and parts for AR-15’s, but what if you designed one from the ground up to use a dedicated 9mm receiver with as many bolt on AR-15 advantages as you could get? Well, you’d get a Just Right Carbine! The JR Carbine is a dynamite little 9mm rifle, and is often more inexpensive to buy than to outfit a true 9mm AR. Handily, for Canada at least, it’s also non-restricted. For another take on the JR and parts swap, check out Matt Capranos’ article.
Just taking in parts compatibility with popular AR-15 aftermarket parts, you’ve got compatibility with:
- Forends (with some adjustment or shims necessary)
- Commercial spec buttstocks, though you can swap out the buffer tube if you prefer milspec.
- Trigger groups
- Magazines (Glock and 1911 mags depending on your rifle)
- 9mm muzzle brake or flash hider
From the factory, the JR carbine comes with a more standard M4 style adjustable buttstock, but is perfectly happy taking on popular buttstocks like the many products from Magpul. The included forend is a free float (no gas tube, no gas block), quad rail affair. Not bad, but I felt a longer tube style forend would work better in the brush and I had one handy. The stock A2 style pistol grip was tossed for a more rubbery one from FAB Defense. For fast, short range action, a red dot was chosen for the optic. That’s a lot of options for a pistol caliber carbine! Indeed, compare the look of the JR carbine above, to the one that Matt Capranos built. The trigger on this particular JR Carbine wasn’t too bad, so a new trigger group wasn’t deemed to be necessary.
Function and Use
A few things look a bit out of sorts on the rifle until you use it. For example, the mag release button on the left: that’s the wrong side! Oh, until you pull the mag out and see that the button is easily actuated with your thumb. A minor annoyance is the lack of an automatic last-shot bolt hold open, but it’s quick enough to rip a mag out, replace it with a new one, rip the bolt back, and keep firing. What should the JR Carbine be used for? I think it makes for a cracking home defense weapon, or as a short range small game rifle. 9mm is cheap, low recoil and when fired out of the long barrelled JR Carbine, isn’t too bad without hearing protection when you’re out hunting (always use hearing protection when plinking or at the range though). Those attributes also make it great as a rabbit gun with more stopping power than a 22.