I always see don’t clean your rifle until the accuracy starts to fall off.  

So how many rounds does it take until accuracy becomes unacceptable for you?

I see a noticeable drop around the 175 mark for my bolt gun and 300 or so in my AR15.

Factors I think come into play:
1) How accurate was it to start with?
A 0.25moa rifle might show visible losses after 40 rounds, but you might not notice any degradation in a 1moa rifle for 300.

2) The chambering and type of barrel have an impact. A rimfire with a lapped barrel will go hundreds of rounds with no change while a rough button rifled .300wm might foul up in 40 rounds.


Personal experience:
My 1moa factory-barreled “normal” rifles start to get loose around 120 rounds. At least that’s where I begin to notice.

My precision rimfire will go at least 300 rounds before it starts to open up and I need to scrub just a few inches past the chamber.

My single-point cut rifled, lapped 5.56 SR that shoots 1/2moa starts to build excessive pressure from carbon ring before I notice accuracy falling off, and that happens around 130 rounds.

So my policy is 120-140 rounds as a general rule.

My personal experience is that my .5 MOA rifle will open up to .75-1.00 MOA around 150 rounds and after 175 rounds it won’t hold 1 MOA with the same load.  

It seems like your experiences are similar to mine.

I dunno what kind of <expletive> y'all are shooting but I'm going to bet you're talking about guns with factory button rifled barrels. Once you ditch the machine mark riddled factory barrels then the world opens up to you like an oyster sick of carrying its pearl.

The last PRS match barrel that I burned up and replaced went 1800 rounds on an expected life span of 1300 rounds as a .243AI spitting 115's at 3200fps. It was cleaned twice in its life and shot 8-10 round strings rapid fire its whole life. My metallic silhouette match rifle's barrel in 7BR has something like 7,000 rounds through it and is still kicking though it has slowed down a little, accuracy is unchanged. It's been cleaned 4 times in its life. A 6XC barrel I retired and replaced had 2000 rounds on it and had just begun to slow down but was still making bughole groups. It was cleaned after every single time it was used. My 2 current 6XC's each have ~400 rounds through them now, they've never been cleaned and are just as good as they were at 20 rounds.

A buddy of mine has a .30-378 Weatherby which saw the original barrel completely poop the bed before 600 rounds which sucked for him since he used that rifle for everything from squirrels to brown bear so he had used most of his barrel's life developing loads for everything from varminting to large predators and barely got to shoot the thing at anything but paper before its throat was 5 miles of gravel road. He re-barreled it in the same chambering but then bought a few more rifles and now enjoys life without a persistent TBI from blast overpressure.

I literally shot my last barrel out at 3600 and never cleaned it. I dont clean until accuracy opens up normally and that's probably a few times at most in a barrels life. I mean why clean it if its working.

My luck would have it go to poop when I need it to perform. Unless using a rough bore or big bad powder charge and bullet combo, just give it a little love every few hundred rounds to stay ahead of the dip.