3-groove 6.5mm barrels, pros and cons

[AKDaddy]

My father in-law has built many custom rifles and we are talking about doing simultaneous builds together, sharing a reamer, gunsmith, etc. We're looking at a 6.5mm round, probably 6.5x47L, but the .260 Rem and maybe even 260 AI isn't ruled out yet either. What I have in mind is a cross-over tactical/hunting rifle, with the best accuracy you can reasonably squeeze out of a rifle you'd still care to carry for any distance afield.

Here's my question: What are the pros/cons to a 3groove barrel?

My father-in-law built a superb shooting .308 6 lb hunting rifle for my wife using a Benchmark 3 groove barrel. I love it because it cleans so easily too!

Should we consider using 3-groove, 1-8.5 twist barrels for our 6.5's? Why or why not?

 

[BlackHawk95]

I think the number of grooves a barrel has doesnt really make alot of difference, from what Ive seen..

They may clean a little better. But I would say if you didnt know one barrel was 3 grooves and another was 5 grooves you prolly wont be able to tell the difference..

Having said all that, I happen to have to have a 3 groove cut Lawton barrel in a 6.5x47Lap thats just a tack driver..

But, Building a rifle is mostly about what barrel you want to shoot, And if a 3 groove is what you want I dont see any not to get one.

 

[AKDaddy]

Thanks for the input. My father-in-law said that 3-groove barrels often shoot faster and clean more easily, which was his motivation. Of course speed is secondary to accuracy in my book, so I thought I'd ask.

In reading up on this I just noticed that very few (if any) experienced/top shooters seemed to be ordering 3-groove barrels, and was wondering if there was something I should know about them. Accuracy? Barrel life? Or is it there just no reason to go there at all?

 

[AP2020]

I, too considered a 3-groove until I read this on another site:

Re: 3 groove Barrels
I have used 3 groove barrels in my high velocity wildcats in 25 cal, 6.5mm, 270 cal and 7mm extensively.

I have not had one that was a bad copper fouler but I have heard some are. I would say I have used roughly 12 of these barrels in the different calibers listed above in velocities up to 4100 fps in the 25 cal and 4250 fps in the 6.5mm barrels.

I am familiar with Bill Baileys rifle and agree it was much more of a fouler then I have experienced with my personal barrels and tests.

That said, I have seen this with every different barrel design out there, every once in a while some will just foul more. I had a Lilja 1-8 30 cal barrel that you could shoot 5 shots through and have 3 cents worth of copper in the barrel after those shots.

Called up Dan and asked him what the problem was. He said to return the barrel and they would check it and relap it if needed. Got the barrel back and its working perfectly well not so things happen every once in a while even with top end barrels.

As far as what you can expect, here are a few things I have learned testing these barrels. Most of these have been fast twist barrels so it may not pertain to your situtation with the 1-15 twist.

- Barrel life is longer. Roughly 15-18% longer compared to a traditional 6 groove barrel. Roughly 10-12% longer then 5 groove barrels and around 8-10% longer then 4 groove. That being all barrels made from the same material and hardness. Some of the harder cut rifled barrels will last longer then save groove count button pulled barrels so you have to compare apples to apples.

- I have not noticed much difference in accuracy with a 3, 4, 5 or 6 groove barrel when all are fitted and chambered properly and the barrel is of top quality.

- I have noticed that the 3 groove barrels are much harder on thin jacketed bullets. Again, this is for heavy VLD or ULD bullets in fast twist barrels. I do not think you will have these issues but if you use a J-4 based bullet, you may have some problems no matter what twist you use with those velocities.

- I have seen some 3 groove barrels produce a bit more velocity then other rifling designs and some a bit less. I have tested them head to head with the 5R and 5S barrels and can tell you that for the three barrels I tested, the Lilja 3 groove produced the least amount of pressure for a given load using the same chamber, throat, bullet and load and barrel length. In fact a comfortable load in the Lilja was leaving a shiny ejector mark on the 5S barrel. All in all, variations from one barrel to another will effect velocity potential to a higher degree then the number of lands in the barrel, especially with conventional cup jacketed bullets. Now with hard bullets thats a different story.

If I am building a rifle for high velocity using very long, very heavy VLD or ULD bullets in a fast twist barrel, I will not use the 3 groove barrels any more simply because of their high baring surface compression % which is just to hard on these bullets and in time you will have problems.

For those types of rifles I will generally use a 4 groove barrel with BSC % in the 20% range and no more.

For conventional chamberings or with very light weight bullets, its not nearly as critical.

All in all, there is not a huge difference between these barrel designs. Break them in well and on average they will behave like any other top end barrel. Of course there is always a chance of a bad barrel but thats the case with any barrel maker.

What bullet will you be using?
__________________
Kirby Allen(50)

..and another opinion

I have used two Lilja 3 groove and two Pacnor 3 groove , both Lilja barrels shot great , fouled very little but their were is reasonably mild rounds one was my 260 the other was 300 win mag. The two pac-Nor barrels both fouled worse than the Liljas but not as bad as a factory barrel one was 22-250 Ackley the other was 243 Ackley.

I know that with the two later barrels they would blow bullets up once the speed was in the 4K range both 1-8 twist. Had to stick with the V-max and Ballictic Tips for the realy high speeds.

I'm pretty sold on cut rifled barrles now especialy the 5R barrels like the Rock Creek , Obermeyer and Bartlein although my next build will be on a buttoned 5R made by Broughton.
I think that the more land and grooves you have makes a realy big differance in keeping bullets together at high speeds , the 3 groove barrles have much wider lands and those put a good bit more stress on the bullet which helps to break them up.

For a real hot rod like your building my vote would be for a 5R from a cut rifled maker , Rockcreek , Obermeyer and Bartlein (in no particular order)

 

[watercam]

After hearing the Springfield '03 barrel story I stopped worrying about how many grooves there are. They were down to TWO grooves towards the end of the war and shot just fine (for their purpose). I have used three groove barrels in two match rifles and they are superb. Lilja made them and they are faster than the four groove tubes I had before. Less friction perhaps? All were custom and lapped. In the end it won't matter much, al the good barrels should shoot.

 

[okie]

it could be argued that a 3 groove will outlast a 6 groove for whatever reasons, but as far as throat life the 3 groove COULD outlast a 6. The lands are much wider---it should take longer for the gases to erode a throat with more land area(metal). I doubt this has yet to be proven, but seems logical to me.

 

[AKDaddy]

Awesome input, interesting discussion. By the sound of it, accuracy is equal, but pressures, velocity, and barrel life MIGHT be improved. The downside being that they are harder on bullets, so ultra high speeds are out. Since I seriously doubt I'll be shooting faster than 3200 fps, and more likely 2900fps, I'm tempted to go with a 3-groove barrel.

I'll keep watching this thread. I doubt I've learned all there is to know so any further experience and input would still be highly appreciated!

 

[BlackHawk95]

As far as throat life on a 3 groove, I had a Lilja 3 groove in .243Ai that one, never shot very well and after about 500 rounds you could see where parts of the lands were starting to wash away.

I swapped that barrel for a Broughton 5C and sofar its shot wonderfull and after 650+ rounds the throat has only moved .010" And there are no signs of the lands wearing away. I believe it had to do with the 5C type lands. as there are no sharp edges on either side of the lands to wear away.

After saying all that. I have a Lawton cut rifled 3 groove barrel in 6.5x47lap that is what I think is the best barrel Ive had so far. it cleans and shoots just spooky good. at 300yds it will damn near shoot the same size groups no matter if the barrel was just cleaned or left for a couple weeks with fouling in it. and shoots to the same point of impact..

Me personally will buy 3,4,5 or 6 grooves just depending on how im feeling the day I get tready to order the barrel. I will say this though, I wont ever buy a any groove Lilja barrel.

Jerid

 

[gary blankenship]

I have a lija 3 groove in 22-243 1:12 twist 52 berger 4200 fps re15 one holer cleans up 4 patches love it

 

[1K6BRA]

A friend and I have been shooting Lilja three groove 6.5 barrels for five years now. We both shoot 6.5 x 47 with moderate loads. (H-4350) neither of us have ever had an issue, barrels clean up well and will usually get match grade accuracy for 1500+ rounds. Lilja's customer service is great and I would recommend them to anybody.

 

[Northridge]

If it will be chambered for 260 or 260ai a 8.5 twist or 8 twist will be fine. Now if it is a 6.5 creedmoor or 6.5x47 lapua 8 twist would be my recommendation. As far as three grooves go for the 6.5 caliber you will not go wrong using one but a 4 groove 5 groove or even six will perform equal to the 3 groove take your pick.

Shawn Williams