View Full Version : 5r rifling is it fad or the real deal
May 1, 2009, 01:11 AM
getting ready to build my first rifle and in my research i am reading a lot about canted land rifling. in theory it sounds like the best thing since sliced bread i am wondering if any of you guys have any experience with or opinions on these barrels. i am rebarreling a rem 700 adl in 243 win circa 1978 ,to 308 win in a rem varmint contour to be cut down to 22 inches. PT&G bottom metal,HS PRECISION pst 82 thumbhole stock,haven't decided on scope or mount yet
May 1, 2009, 04:11 AM
All the sites selling 5R barrels claim they will shoot forever and butter your toast between shots. I haven't heard of any matches won with them yet, but that is really the test.
May 1, 2009, 04:49 PM
Barrett (Boots) Obermeyer, cut rifled barrel maker in Wisconson, designed the 5R rifling shortly after the 7mm Rem. Mag was introduced. Sierra's 168-gr. Match Kings that came out in 1970(?) had a pretty thin jacket compared to their 30 caliber bullets. Conventional rifling shapes cut deep enough in jackets that when bullets were spun too fast, they would come apart shedding their jackets. Sierra has since used slightly thicker jackets on their 7mm bullets.
Obermeyer 5R barrels have won lots of highpower rifle matches setting occasional records along the way. I've worn out 3 of them myself shooting matches and winning some; two in 30 caliber magnums and one .308 Win. Accuracy is as good as it can get. Conventional shaped rifling will shoot the same; either one is just fine.
There's a few copycat versions of his 5R rifling made by other barrel makers and they should do as well as Obermeyers providing the bore, groove and twist uniformity are excellent and properly sized for the bullets to be used.
Be very cautions about anyone claiming a barrel will shoot forever. They probably will, but accuracy will diminish after about 3000 rounds in a .308 Win. and 1200 rounds in 30 caliber magnums. 7mm magnum barrels go about 900 rounds and my and a friends .264 Win. Mag. barrels went south between 600 and 700 rounds. This is typical of Obermeyer, Kreiger and Hart barrels. Shilen barrels tend to have only 2/3rds this much life before accuracy starts down hill.
May 1, 2009, 05:20 PM
From what I read, Boots O. brought out 5R barrels shortly after samples of the AK74 made it to the Free World. 5R stands for 5 groove, Russian pattern. (The AK74 has 4 grooves, he maintained the trough shape but went to 5 grooves which have been well proven for a hundred or so years. For that matter, trough shaped grooves were not new when the USSR picked up the plan. I think the precision of manufacture is what counts, not the shape of the grooves... but then I am not a match winner.)
May 1, 2009, 08:52 PM
Jim Watson, you may be right about Obermeyer's source of the idea to make 5-groove barrels. He told me at the Nationals some years ago where he got the idea but I forgot.
Meanwhile, an interesting thing about the number of grooves and their success with different bullets. US Military barrels have been 4-groove for 30 caliber ones (including the NATO version) since their inception at the turn of the last century. 4-groove barrels shot all kinds of bullet weights very accurate in 30 caliber bores. Along came Hart, Douglass and a couple others making 6-groove barrels and bullets lighter than 160 grains didn't shoot all that accurate compared to those heavier that were excellent. Obermeyer's 5-groove ones fell somewhere in between them.
Since their inception in early 1991, the 155-gr. Palma bullets have always shot best from 4-groove tubes. Ruger's 20 or so rifles they gave the US Palma Team back then had ten each of 4- and 6-groove barrels made by Green Mountain in Vermont. There was a clear difference in accuracy; the 4-grooved ones did best. too bad only one shot half way decent compared to the other nineteen which were not worth chambering a round in.
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