Home Forums Hunting & Shooting Long Range Hunting Number of Barrel Groves

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?

I had to rebarrel 16, 7mm Allen Magnum rifles on my dime for just this reason. They were the original batch of rifles designed to shoot the 200 gr ULD RBBT wildcat bullets.



Every one of them shot amazingly well until they hit from 200-300 rounds down the barrel. Then it was like a switch was flipped and the rifles went from 1/4 to 1/3 moa rifles to having 50 to 100% of the bullets coming apart in flight.



That said, these were being loaded to a velocity of 3200-3350 fps with the 200 gr ULD RBBT bullets. After this occured, nearly every rifle still shot very well the 160 gr Accubond bullets loaded from 3400-3550 fps.



Obviously this is higher velocity levels then you will be dealing with so that may help you dramatically.



Also, I have found that the 180 gr Berger will take slightly more abuse then the 200 gr ULD RBBT. The reason is because the 200 gr bullets were made on 30 cal J-4 jackets that were reduced in diameter to work with the 7mm bore size. This certainly work hardened the jacket and this may also be the reason for the bullet failures once the barrels got 200-300 rounds down the barrel.



I will say that in my testing, the Berger 180 gr VLDs shot very well in most of these barrels as long as they were shot at velocities under 3300 fps on average..



That said, with the VERY fast twist which is much more then needed for either of these bullets, once the barrels get some wear on them and the throat roughens up, you may start seeing some issues but I suspect at the velocity range you are at you will not see this nearly as soon as the 7mm AMs did.



The cure was pretty simple, go to a 1-9, 4 groove barrel or a thin land Rock 1-8.7 5R barrel which seem to solve all the problem.



I have a 7mm AM that has a Lilja 1-9, 6 groove and it was tearing 200 gr ULD RBBT apart and last weekend I tested the 180 gr Berger in it and they shot very well, at least for a barrel with the number of bullets this one has down it, roughly 800 rounds.



Again, I would suspect you will see problems MUCH farther down the road then we did and possibly you may never see a problem before the barrel is ready to be replaced.

i'm runnin' a couple of Lilja 3 groove, 1-8" .264 Win barrels with no complaints.

IMHO the 3 groove makes sense, simply because its not land opposing land and groove opposing groove so should be easier on the bullet as a whole.

there could be a issue with long VLD type bullets, I have no experience with the long-heavy for the caliber VLD's in any caliber.

Thanks for the info and confidence boost in my 3 groove choice.

I've got 'em all.

I'll Pass on the 3-groove..................