One of my commenters here pointed out that the Mini-14 doesn’t wobble like an AR does. My response to him included the wording of the title of this post. I couldn’t help my urge to turn it into a title. I have heard that I have impulse control issues. Anyway, no matter.
If an AR wobbles, it’s generally in one of two places, sometimes both. The upper and lower fit and/or the traditional handguard. We now see some AR receivers with built set screws to addressing this but in many cases, just buying a decent grade AR helps.
The slop in upper to lower receiver fit is one reason I’m not a huge fan building ARs with uppers and lowers from different companies. Occasionally things can go the opposite direction and you can find that the fit is too tight. Such as the case between a Spike’s lower and an upper whose origin I’ve since forgotten.
Now, if you have a sloppy hand guard, you have two options. Live with it or replace it with a free float unit. Should you choose to replace your handguard ALG has some affordable options available. Though if you don’t have the expertise to address it, you will have installation costs. In the end, it comes down to what the desired purpose of the AR is.
One last thing, if you’re buying an AR and it wobbles, and that bothers you, don’t buy it. You have lots of good options, right now, for cheaper than they’ve been in years.