UPGRADING A 6MM ARC HOWA MINI

Recently, I decided to discover whether all the fuss about the 6mm ARC is warranted. Unfortunately, there aren't a lot of factory bolt-action rifles chambered for this cartridge, with Savage and Howa representing a good chunk of the market. Of course, going the custom route is always an option, but my gun fund was in no shape to go that route, so I turned my thumbs down on having a gun built. In the end, a fortunate encounter at a trade show put a Howa 1500 Mini bolt-action rifle into my hands at a very reasonable price.

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Mine is the basic model with a black synthetic stock, 20-inch barrel, and five-round detachable magazine. For those unfamiliar with the Howa Mini, it's a push-feed, flat-bottom action with an integral recoil lug. The action is about ¾-inch shorter than a Remington 700 short action, while the bolt is 0.080-inch smaller in diameter, making for a significantly trimmer rifle. That bolt has a two-lug design, sturdy extractor, and a typical plunger-type ejector. The rifle is about 39.5 inches in overall length.

The barrel is reportedly hammer forged, and a borescope inspection showed a smooth bore, free of toolmarks, promising good accuracy and easy cleaning. As is common these days, the muzzle is threaded, making installation of a brake an easy DIY project. The barrel measures 0.730-inch at the muzzle, giving it some heft

As usual, I started shooting the rifle with some factory ammo to get a handle on this rifle's potential. Howa claims sub-MOA accuracy for three shots with quality ammo, so I tried some Hornady Black ammo launching 105-grain BTHP bullets at 2565 fps. I fired five consecutive 3-shot groups to test Howa's claim, and every group met that standard, with the average being 0.61 MOA. That's stellar performance and sets a high standard for trying to be equal with handloads, also giving me the go-ahead to make some modifications.

The Cartridge

The 6mm ARC has an interesting history in that it was developed by Hornady at the request of some US military units to increase the reach and lethality of the standard-issue AR platform and 5.56mm NATO ammo.

Because ammunition manufacturers have no control over which rifles their ammo is used in, it all must be loaded to a minimum safe level. The 6mm ARC, about 52,000 psi, is the maximum safe pressure for semi-auto rifles chambered for this cartridge. Bolt guns, however, can easily handle 62,000 psi, meaning the only way to get maximum performance from the 6mm ARC in a bolt gun is to handload. Available literature suggested the extra 10,000 psi should yield an additional 100- to 150-fps in barrels of equal length.

Modifications

Everything suggested the rifle was worth a few upgrades, so for some one-stop shopping, I went to MDT. The big-ticket item was a new stock in the form of MDT's ORYX chassis system. It adds solid bedding, some needed weight, an adjustable cheekpiece, lots of M-LOK slots, a buttstock adjustable for length, and an AR-style grip.

A Pic rail for solid scope mounting came next. MDT's rail for the Howa Mini has 20 MOA of incline built in, is Mil-Spec, and has plenty of length.

The last item was a muzzle brake in the form of MDT's COMP Brake. It's the only one with adjustable top ports allowing the shooter to fine-tune muzzle rise. So, it earned a spot on the Howa's barrel.

The trigger on the Howa Mini is a two-stage type with some adjustment capability, and while many users have reported excellent results with it, I couldn't get some creep out of the final stage. This prompted me to order a Timney replacement and swap it for the factory trigger. Installation took only one minute and the removal/replacement of a single screw. However, the safety wouldn't move to its most rearward (bolt locking) position. This necessitated shortening the tab that locks the bolt handle via some careful grinding and polishing. It was a quick-fitting job, and now all three positions work properly. As I've come to expect from Timney, this trigger has been performing flawlessly.

In my initial testing, I had dropped a Vortex Light Hunter scope on the rifle. While it was a great match for the rifle in its factory configuration, its maximum 10X magnification isn't enough for stretching out this rifle. I had an older Leupold VX-3 8.5- 25x50 sitting unused, so I mounted it. With target knobs, a fine reticle with a good assortment of MOA-based hashmarks for elevation and windage, as well as side-mounted parallax adjustment, it's been working great.

Results

I've been banging steel with the rifle in its modified form during multiple range trips so far. Ammo has been handloads using Hornady's 108-grain ELD-M bullets, LEVERevolution powder, Hornady cases, and Federal 205M primers. Muzzle velocity is 2645 fps.

I'm finding it's possible to spot my own misses in the rifle scope, mild recoil is cheap to shoot for a centrefire, and I'm getting good audible and visual feedback when I make a hit on steel. So, I'm calling the project a success. Of course, I can't leave well enough alone, and some further tinkering with this rifle is in order, as I'd love to replace the 20-inch factory barrel with a heavier match grade tube at 22- or 24-inches. However, that's not in the budget right now.

If you're looking for an excuse to build or buy a new rifle, consider the Howa Mini as a platform with a lot of capability.

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