ATI .22LR upper for Omni Lower


ATI .22LR upper for Omni Lower

The ATI rimfire AR upper is, at first glance, an odd design. Surrounded by a quad rail, this polymer frame upper defies categorization, being neither a bull barreled target precision rig nor a light, quick-handling trainer. The barrel is of medium weight, and the hefty quad forend bring “tactical” configurations of decade ago to mind.

The Omni Hybrid lower, mainly polymer with metal-reinforced buffer tube housing, comes with a surprisingly good trigger. In general, ATI supplies their ARs with triggers a grade above milspec. Like other polymer lowers, Omni Hybrid requires an effort to mate with the upper. The pin spacing is sloppy but workable. My second, newer Omni lower fit a 5.56 upper perfectly, so it looks like the fit issue has been addressed. The fit and the design is considerably nicer than budget polymer lowers. Unlike GWACS lowers I’ve used on a number of rifles, ATI lower supports telescoping stocks and the buffer detent area is also reinforced with metal.


The upper ships with a Chiappa-branded 28-round magazine. It has quite a bit of play in the mag well, which works fine unless the magazine is rested against the shooting bench. After several mis-feeds, I gave up on it and switched to Black Dog Machine 15-rounder. Chiappa rimfire magazines are hit and miss in general, and more so in this lower because of the wide mag well. BDM magazines worked 100%.

The rifle lists for $494 on the ATI site, which is not cheap for a .22. My first impression of it was unfavorable: the medium barrel combined with the quad rail make it distinctly front heavy, and the quad forend is rough on the support hand unless covered with rail covers. I mounted a Primary Arms 5-power prismatic scope on it, a typical optic for the centerfire counterpart, and took it to the range just to see if it had any redeeming features besides the good trigger. Turns out it has a big feature called ACCURACY. Serious, consistent accuracy.

Five shots at 26 yards, with all bullets impacting pretty much on top of each other. That's how this rifle shoots consistently with Aguila, Eley and CCI match ammunition.
Five shots at 26 yards, with all bullets impacting pretty much on top of each other. That’s how this rifle shoots consistently with Aguila, Eley, and CCI match ammunition.

At 25 yards, which is all I had available indoors, it shot 1/4″ groups with CCI Mini-Mags. 1MOA with High-velocity ammunition is respectable for a heavy barrel bolt action, much less a semiauto. With Eley Match, CCI Green Tag, and Aguila Rifle Match, groups looked more like single holes and measured around 1/6″ or 2/3MOA. I am not a particularly great shooter, but I was able to fire numerous groups of that size easily. Even better, the rifle showed minimal shift of impact between ammunition brands. Predictably, hypervelocity ammunition (CCI Stinger) grouped closer to 1.5MOA–entirely adequate for varminting at realistic ranges. All that with a scope focused at 100 yards! The rifle might well do even better with a parallax adjustable optic.

So this oddly configured rimfire upper proved reliable and extremely accurate. I originally planned to swap out the forends, but I don’t want to mess with proven high performance. A semi-auto match rifle under $500? That’s not a bad niche to fill.

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