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Need groove advise...3 or 6?

 
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  #1  
Old 05-02-2013, 09:04 PM
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Need groove advise...3 or 6?

I am in the market for a new barrel. I am leaning toward a Lilja in a .308 sendero contour. The part I am having trouble with is the grooves. I have no idea the pros and cons of the too. I am currently shooting 230 Bergers with very good success with a factory 26' barrel.

I need your help....please explain the difference and the best choice for selecting a appropriate groove for a 28' sendero barrel.

Thank you very much!
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Old 05-02-2013, 09:32 PM
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Re: Need groove advise...3 or 6?

Tagging in, want to hear more of this myself.
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Old 05-03-2013, 06:52 AM
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Re: Need groove advise...3 or 6?

I am by no means an expert but the three groove will not put a land opposite another land which the 6 groove will. I have heard one reason is the idea behind non opposing lands is theoretically less stress on the bullet. Below Dan Lilja talks about less throat erosion.

I have had two 3 groove liljas. Can't say if the number three is the cause BUT once the throats became worn they would cause VLDs to become damaged and the rifle would shoot flyers. The same thing might happen with a 6 groove but don't know.

Here is what I HAVE observed:

First 3 groove was an ill advised 1 in 7 twist in 7 Rem mag to shoot the 180 VLD. At round count 225 or so the rifle would shoot occasional flyers that would diverge as much as 3 ft off POI at 100 yds! I think the twist was responsible for the bullet coming apart with such a low round count.

The second 3 groove faired better. It is a 1 in 10 twist 257 weatherby. I shot 115 VLDs to approx. round count of 550 then began to shoot flyers. Not as far off POI but enough for me to switch to a bullet that would not be affected by the rough throat. Now shooting a 110 accubond. Round count is close to 1000 and while it is a nasty fouler and looks horrid through a borescope it still is very accurate.

I have no idea if a 6 groove would have done the same thing or not.


Here is what Dan Lilja says:

Q. What are the differences between 3 Groove and 6 Groove Barrels?

A. Almost all of the caliber and twist combinations in the rifle barrels we make are available with 6 lands and grooves. A few years ago we started to make barrels in a 3 groove configuration too at the request of some varmint hunters who were looking for longer barrel life. They were chambering barrels for hot 22 caliber varmint rounds and shooting the throats out of conventional 6 groove barrels fairly fast. We reasoned that if we reduced the number of grooves to 3 but kept the ratio of land to groove width the same (ie. the lands are twice as wide in a 3 groove barrel as compared to a 6 groove) that there would be more land area to resist heat erosion.

Well, it turned out that barrel life did increase and that accuracy stayed at least the equal of comparable 6 groove barrels. It is hard to put a percentage increase on barrel life but a conservative estimate might be 20%.

Benchrest shooters are always experimenting and looking for a competitive edge. Before long a few shooters, including Dan Lilja, were putting 3 groove barrels in 6PPC and 22 Waldog on their light varmint and heavy varmint class benchrest rifles. And these barrels proved to be very accurate. They started winning benchrest matches and soon became popular among the benchrest shooters. .

On the right is Dan with a .193" 200 yard group fired at a benchrest match in Billings Montana in 1998.

This was with a 6 mm PPC 13" twist 3-Groove Barrel.

And we found that as a side benefit the 3 groove barrels seemed to foul very little and clean up quickly. We attributed this to the reduced number of corners inside collecting powder and copper fouling.

This answer to 3 groove - 6 groove question is not meant to discredit the 6 groove barrels. They have consistently shoot extremely well over the years. Dan continues to shoot both 6 and 3 groove barrels on his benchrest rifles. But if you haven't tried a 3 groove you might consider one the next time you need a barrel. We do not offer them in all of our caliber and twist combinations. Our page with caliber and twist listings indicates if a 3 groove barrel is available. And we are frequently adding 3 groove buttons to our offerings. If you don't see that a 3 groove version is offered in the caliber and twist you're looking for, ask, we might soon be making it.
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Old 05-03-2013, 03:28 PM
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Re: Need groove advise...3 or 6?

I have positive experiences with 3 groove 6.5 barrels running 140 grain VLDs at normal 6.5x284 speeds. The negative things I hear is from 7mm and smaller caliber users running bullets well over the 3200'sec mark. I've never heard of any complaints from larger caliber users.

I'll own more.
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Old 05-03-2013, 04:11 PM
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Re: Need groove advise...3 or 6?

Some years ago, "Greek" 3-groove rifle barrels used in .308 Win match rifles were pretty good. They shot Sierra 168's through 190 grain HPMK's very well. 200's and heavier not quite as good. Don't remember the man's name who made 'em but it was a Greek one. Nice guy, too, from folks I've talked with who bought them.

All of Sierra's match bullets have shot well in 4 and 5 groove barrels. Bullets lighter than 160 grains seem to shoot best in these twists. 6 groove barrels never shot the 155's quite as accurate as a 4 or 5 twist one, but with heavier bullets they won virtually all the matches and set virtually all the records with bolt guns.

So, I'd recommend a 4 or 5 groove barrel to handle the greatest weight range of 30 caliber bullets. 5 or 6 groove for bullets 160 grains or heavier. Barrel length is not an issue for selecting groove count.

Regarding bullets coming apart in flight, most common cause is the rifling's lands engraved them such that they weakened too much at the land/groove corners at bore diameter. This was the problem with a lot of 28 caliber bullets when the 7 Rem Mag first came out. Boots Obermeyer used a 5-groove radiused rifling that worked with such bullets spun so fast from the 7 Rem Mag's 1:9 twist barrel and high muzzle velocities that solved the problem. I think jackets are better these days.
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Old 05-03-2013, 07:24 PM
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Re: Need groove advise...3 or 6?

I have my own self proclaimed idea of 3 grove barrels and jacketed bullets on game. I feel the 3 grove offerings inscribe the jackets deeper and this COULD be what causes some VLD bullet failures especially in smaller faster chamberings. It seems there sure has been a lot of complains about 130 and 140 gr bullets from 6.5's and 260' coming unglued. I have talked to some of these shooter and found it interesting that many were using 3 gr barrels. For this reason I stay with 5 and 6 grove barrels. That and the worst shooting 300 win I ever owned had a 4 grove, but this could have just been a new tube that was bad.

Jeff
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