If it's the only can someone has, there's a good reason.
If it has little to no POI change, there's a good reason.
Those are not reason to buy them, those are reasons to use it if you already own it for another rifle. There are 10+ great rifle cans that won't screw with POI and will give better performance is basically all other metrics to choose from if you are buying specifically for a bolt gun as OP probably is. if you are not and you are buying for another host that isn't an AR but is semi auto (like say a Tavor) primarily, but also plan to run the OSS on bolt guns then sure, fine, that makes sense. But that isn't the situation I'm describing or OP is describing, and therefore isn't a reason to buy one if you are primarily getting a suppressor FOR a bolt gun (or AR).
I have a titanium OSS can in 7.62 (HX-QD 762 TI ) for my 6.5 Creedmoor Tikka T3x TAC A1, 6.5 Grendel AR and my 5.56 AR. Works like a champ, I did not have to adjust my adjustable gas block for the gas guns, no gas in my face, no POI shift and it's quiet. I tend to keep my mouth shut when I do not know anything first hand, I certainly do not keep Internet rumors and myths alive.
Yeah I'm not saying they don't work, or won't work on bolt guns or ARs, far form it. I'm saying you can have a shorter, lighter, less expensive can that does a better job suppressing flash AND noise to the shooter and the environment for a bolt gun (or AR). There just isn't a case for someone who is buying a can specifically for a bolt gun or an AR with an adjustable gas block (outside of some very small niche cases) to buy an OSS over the other superior options out there as mentioned above.
I actually like their cans quite a bit and they perform very well for what they are, but it is an niche product at its core. Unless you like spending more to get an inferior product there are simply better options for most uses. Again, if you have one and you use it on hosts for which it is non-optimal, it isn't like it just doesn't work, far from it. It works quite well, just not AS well as something else might.
The internet myth here is that the OSS cans are great cans which are superior to everything else in all situations. The reality is quite the opposite, the two most popular rifles in the US (bolt guns and ARs) are almost always better off with something else. There are still huge swaths of the market for which OSS is a superior suppressor like on M14s, Garands, Mini 14s, AUGs, AKs, and so on. But that is by definition a niche.
