barrels: fewer grooves better???

[Danny308]

I heard one theory that for large cased/overbore rounds a barrel with fewer lands/grooves has slower errosion due to the lands/grooves being physically larger. Proven, disproven, unknown, or pure BS? Does anyone make 3-4 groove barrels??

 

[Jake in NC]

..I just got my 3 groove 7mm barrel from Pac-Nor.. But it's going to be a 7-08AI so I don't know if it'd be a good one for testing wear resistance.. I've also heard that they're easier to clean (less nooks&crannies for gunk) and a little faster.. None of this has been "officially substantiated" as far as I know.. Lilja makes a 3 groove, also.. Good luck.. d:^) JiNC

 

[snicl1]

I'm sold on that theory, My 300 winmag had a shilen bbl & lasted about 1500 rounds before the groups opened up to over 1 moa. I replaced it w/a 3 groove Pac-Nor & have put about 800 rounds through it. Measuring w/a stoney point comparator, I've seen the O.A.L. to rifling move .47" in about 800 rounds. When the shilen was replaced the O.A.L. of the rounds had to the rifling had increased by .167". None of this is scientific proof since I experimented w/alot of lightweight bullets w/the first barrel as well as various powders (H380 to H870 w/155 - 220MK's). The Pac-nor has only had 190 - 240MK's and powders faster than RL 22 have not been used. That may account for my barrel seeming to erode at a slower rate than the 1st barrel. Either way, I'm happy with it & will replace it w/another 3 land & groove barrel when the time comes.

Hope this helps,

Chris.

 

[chris matthews]

The lands in a three groove are very narrow, not at all equal to the width of the grooves.
The reason they work is they deform or "work" the bullet less than a conventional 6 groove.
A 5R or polyganol rifled barrel does the same.
Plus, barrels with odd number of lands and grooves are easier on bullets by the fact that when a land displaces the bullet it has a groove on the opposite side. 6 groove barrel have two lands opposing to squeeze the hell out of the barrel.
All of this means less pressure/friction/heat to erode the throat.

[ 03-07-2004: Message edited by: chris matthews ]