I recently picked up one of the Hammerli R1 rifles, more or less on a whim. It was relatively cheap, and I like the aluminum furniture. I bought extra 20-rnd magazines for the thing on sale for something like $13/each.
After fixing the ridiculously heavy (NINE pound) out-of-the-box trigger, I get a surprisingly crisp 4# break, and surprisingly good accuracy. Threw an old Comp M2 red dot on top, dumped the amazingly crappy factory flip-up sights for some Magpul slightly less crappy BUIS I had lying in a box o’ parts, popped a spare Blue Force two-point rig into the (correctly sized) QD sockets, and found it to hold about 1 MOA at 100m with a fairly hot Aguila 38 grain hollow point. It will shoot one ragged hole off a bench at 25m.
Added a bit of weight to the fore-end to get it to a similar weight and balance as my Colt M4A1 SOCOM, and I can say that while it doesn’t have the exact same manual of arms as a real AR (specifically, the bolt drop maneuver), it is a useful training device for me, with good accuracy and reliable function with everything I’ve fed it- the aforementioned Aguila, some quite good 40-grain GECO, 36-grain Winchester, 38-grain American Eagle, and a bunch of other 20-year-old detritus from the bottom of my old .22lr pistol range bag.
I’ve put ~750 rounds down range with the silly thing and it has gone bang each and every time. I find it useful for keeping my offhand and improvised field position shooting more or less flexed, and it lets me do things like pistol transitions and sling manipulations that carry over quite agreeably to my real poodle-shooters.
It is also surprisingly fun to shoot- it’s been years since I’ve shot much rimfire. And I have a good supply of those little .22 LR bits of ballistic wampum. So, cheap fun with a bit of practical utility for training.