The vast majority of variable makes and models AREN'T reliable.
Sorry, I don't agree with that, today.
20 years, ago, maybe.
I've manage to take pretty good care of mine, but as they say, schitt happens.
I've had to get off a horse in a hurry & bang the scope hard & I've had horses lay down & roll with the rifle in a scabbard & the scope has survived & I've never had a variable go bad under any other circumstance either........but as you say it does happen.
And & at some remote statistical level, I'm sure variable do fail more frequently than fixed scope do........but that's a very low calculated risk.
Prolly 20-30x the number of variables sold today vs fixed; unfortunately, lots of cheap, really cheap, variables make up a high % of those sales, which likely have a slightly higher failure rate than, say, NS, or even Leupold.
