5R rifling is a type of rifling that has grooves with tapered edges instead of 90 degree edges.
The 5 is the number of grooves and the R stands for Russian. The Russians were the first folks to pioneer it but “Boots” Obermeyer was the first guy in North America to use and perfect it.
According to some 5R rifling gives you a couple of advantages. First off the odd number of grooves ensures that that the lands aren’t lined up directly across from each other in the bore. The theory is that this provides less “squeeze” on the bullet as it enters the barrel. Some find that 5R barrels run a little faster(more velocity for the same powder charge) than 4 or 6 groove barrels.
Secondly, some also find that 5R barrels clean up better. The angled groove edges, instead of the 90 degree edges may allow the patches and brushes to remove fouling easier.
Yes we offer it! And we don’t charge you more for it. If you order a 5 groove barrel from us it will be a 5R barrel unless otherwise stated.