http://accurateshooter.wordpress.com/2009/10/16/krieger-barrels-now-offers-5r-rifling-option/
Krieger Barrels, respected maker of cut-rifled match and hunting barrels, announced it will offer 5R rifling for 6mm, 6.5mm, 7mm, and .308 caliber barrels. This kind of rifling features 5 lands and 5 grooves, but the lands are angled (slanted) on the sides (rather than 90°) for a gentler transition between land and groove. Krieger’s 5R rifling slants BOTH the leading and trailing edge of the lands (unlike “ratchet” rifling which is angled on one side only). 5R rifling also places each land opposite a groove. Having lands opposing grooves, along with slanted sides on the lands, is thought to give a better gas seal and reduced fouling. Additionally, some folks believe 5R rifling reduces jacket deformation by displacing less jacket metal. Overall, proponents of 5R rifling say it helps a barrel foul less and deliver more velocity than conventional rifling.
5R rifling will add $30 to the cost of a Krieger barrel. Krieger will NOT offer 5R rifling for gas gun barrels. Additionally, 5R rifling is offered only for constant twist-rate barrels. So, you can NOT get a gain twist barrel with 5R rifling. At this time 5R rifling is limited to 6mm, 6.5mm, 7mm, and 30 caliber bores, as listed in Krieger’s official announcement:
“<span style="font-weight: bold">Thanks to approval by Boots Obermeyer, Krieger Barrels, Inc. is now offering the true Obermeyer 5-R rifling pattern as an option on limited calibers with our barrels.</span> We are very proud of the fact that Krieger Barrels was chosen as the only Obermeyer-approved maker of his style of 5-R rifling in North America. At this time we are limiting the 5-R option to the calibers listed below, but may offer others in the future as greater demand arises. There is a $30.00 up-charge to the base cost of the barrel for 5-R rifling. Currently available calibers:
- 6mm (.236″ & .237″ bore diameters, .243″ groove)
- 6.5mm (.256″ bore, .264″ groove)
- 7mm (.277″ bore, .284″ groove)
- .30T Palma (.3065″, .3070″ & .3075″ groove diameters)
- .308 cal (.300″ bore, .308″ groove)
5-R rifling is ONLY available in standard bore/groove dimensions listed and standard twist rates at this time. Please call if you have questions about availability of a certain caliber/twist combination. Please note, we are not, and have no plans to offer 5-R rifling in our finished ‘Gas Gun’ lines of M14, M1 Garand, AR-15, and AR-10 variants.”
Krieger Barrels, respected maker of cut-rifled match and hunting barrels, announced it will offer 5R rifling for 6mm, 6.5mm, 7mm, and .308 caliber barrels. This kind of rifling features 5 lands and 5 grooves, but the lands are angled (slanted) on the sides (rather than 90°) for a gentler transition between land and groove. Krieger’s 5R rifling slants BOTH the leading and trailing edge of the lands (unlike “ratchet” rifling which is angled on one side only). 5R rifling also places each land opposite a groove. Having lands opposing grooves, along with slanted sides on the lands, is thought to give a better gas seal and reduced fouling. Additionally, some folks believe 5R rifling reduces jacket deformation by displacing less jacket metal. Overall, proponents of 5R rifling say it helps a barrel foul less and deliver more velocity than conventional rifling.
5R rifling will add $30 to the cost of a Krieger barrel. Krieger will NOT offer 5R rifling for gas gun barrels. Additionally, 5R rifling is offered only for constant twist-rate barrels. So, you can NOT get a gain twist barrel with 5R rifling. At this time 5R rifling is limited to 6mm, 6.5mm, 7mm, and 30 caliber bores, as listed in Krieger’s official announcement:
“<span style="font-weight: bold">Thanks to approval by Boots Obermeyer, Krieger Barrels, Inc. is now offering the true Obermeyer 5-R rifling pattern as an option on limited calibers with our barrels.</span> We are very proud of the fact that Krieger Barrels was chosen as the only Obermeyer-approved maker of his style of 5-R rifling in North America. At this time we are limiting the 5-R option to the calibers listed below, but may offer others in the future as greater demand arises. There is a $30.00 up-charge to the base cost of the barrel for 5-R rifling. Currently available calibers:
- 6mm (.236″ & .237″ bore diameters, .243″ groove)
- 6.5mm (.256″ bore, .264″ groove)
- 7mm (.277″ bore, .284″ groove)
- .30T Palma (.3065″, .3070″ & .3075″ groove diameters)
- .308 cal (.300″ bore, .308″ groove)
5-R rifling is ONLY available in standard bore/groove dimensions listed and standard twist rates at this time. Please call if you have questions about availability of a certain caliber/twist combination. Please note, we are not, and have no plans to offer 5-R rifling in our finished ‘Gas Gun’ lines of M14, M1 Garand, AR-15, and AR-10 variants.”
