I don't believe the round count is going to necessarily help you because there is a possibility that BM has changed the size of the Gas Regulator "GR" port hole from the first rifles shipped/released. You might have to consider the serial number/date of manufacturer of those rifles as it relates to the round count - to see if the rifle is having any stoppage issues. I think it's fair to say that any issues that have been brought up previously in this forum have primarily stem in dealing with the GR if any at all.
So you would have to take into consideration, date of manuf, round count and if you want to get really specific what type of ammo, type of magazines, and are you using the S/U or new H/L GR. But, round count and date of manuf would get you started.
There is a new H/L "GR" that BM has available that might correct issues with earlier rifles, and then again there are those that have other/newer S/N's who have not had any issue at all. Other members here have been posting the size of their GR ports, and from I have been able to figure out, we have different dimensions gas ports on their GR's, which might support my theory.
I personally don't have a lot of data to support this but my belief is...all based on assumptions, is that BM has been tweaking the size of the GR port hole that drive the gas piston back from day one to find the sweat spot. I'm basing this, because there have been many that have NOT had any issues with several thousand rounds down range with newer S/N's. Then you have to consider are they firing .223's or just 5.56's...it's all about pressure and cycling of the bolt carrier group. So, until BM comes out with a press release, that's my story and I'm sticking to it. This one man's opinion.
I just got off the phone with BM customer service to see if I could get any conformation, one way or the other before I posted this reply...and nothing. I got through, but they have their own issues to deal with this month. BM closed their facility in Maine and moved the call center to NC (I believe) in any case they are all new to this weapon and have no history of this rifle from a learning curve respective, or who to go to with for information. I tried to confirm whether or not there have been any running changes, with negative results. All they ("they" meaning customer support people who are usually kept in the dark) have to say is that they will stand behind their product .... and honestly... I believe them.
I also passed on that they need to make it clear and debunk these stoppage issue concerns going forward if they want to increase sales for the ACR. They will only have happy current and future owners of this rifle if they are truthful. They only need to look at the XCR on how NOT to market the sale of a new rifle. I'm keeping my fingers crossed.
Having said all this, I believe the ACR to be an excellent rifle and one what can be easily fine tuned if there is an issues with stoppages or cycling. There are a lot of people on this forum that will concur who have LE and military to back this up.
They are some gremlins in dealing with this topic, but it will all be worked out. I hope this helps.