Some rifles require fouling before grouping settles... sometimes only one shot, sometime more. You just need to learn your rifle... a bore scope is certainly not a requirement... it's just the latest toy.
I have three center fire rifles that will shoot to point of aim from a freshly cleaned bore. That's out of literally going through over a thousand rifles to find them. One is an off the shelf Tikka T3, the other two are custom rifles, one made by an unknown smith and one by me. These rifles are relatively rare exceptions to the herd.
There just aren't many rifles out there that will shoot to point of aim, reliably without the amount of fouling they like.
Some rifles will shoot hundreds of rounds without cleaning but they're very rare as well. The Tikka T3 I have will shoot well over a hundred rounds consistently, before it needs to be cleaned and fouled again.
Most rifles will take at least three to five rounds to settle down to the point they can be trusted to shoot consistently to POA. It's up to the shooter to learn where this sweet spot is.
For most rifles, the sweet spot will give you 20-25 reliably consistent shots.
guntech drops these little gems here and this is one that should be engraved into a newbies memory.
Just fouling the bore isn't quite enough though.
When sighting in a rifle properly, each shot should be taken from a COLD or at least ambient temperature barrel. Ten to fifteen minutes of cooling time between rounds is the norm. Again, not all rifles require this. Some barrels have been specially heat treated or cryogenically stabilized (expensive) to eliminate this issue.
Think about this for just a second, when you're hunting game, your shot will very likely be from an ambient temperature bore. That's the one shot that really counts, so practice in that sweet spot.
How often have you been to the range and a shooter starts blasting away, without allowing his rifle's barrel to cool??? Then looks through his spotting scope and starts adjusting his telescope's crosshairs after every shot.
Most barrels will hit a sweet spot after ten to fifteen quick shots and stay there consistently, as long as you keep shooting.
Most shooters, that don't know what's happening pack up their rifles and leave, right after doing this.
Guess what happens to their first shot on a game animal from an ambient temperature barrel??
I don't mind if they miss completely, it's the wounded animal that runs away, sometimes taking days to die, that bothers me. One of the main reasons I became an accuracy freak.
