Question on grooves. Been using Pac-Nor and ordered another barrel today. I have one blank waiting to become a 375 Ultra, and was talked into a 1-12", but a 3 groove. Don't know how it shoots or cleans as it's collecting dust waiting for the MRC 1999 in a lefty that seems to be as mythical as a unicorn or sasquatch.

Ordered a blank just now for the 300 Win Mag project posted nearby. I got everything how I want it: A #4 fluted contour to finish at 26". Twist is a 1-10" which I feel is the correct rate for 180 grain bullets exclusively. I was suggested another 3 groove barrel, but elected for a 5 groove instead. Figured the odds of ONE being correct is in my favor.

Can someone enlighten me as to the pro's or con's of either rate? The gal at Pac-Nor was easy to deal with, but just backed up the 3 groove referal by stating that "It's what everyone here shoots, and is easier to clean"

Jesse,

Here is my experience with the 3 groove rifling systems. I do not use Pac-Nor barrels, not because of poor quality but because I prefer to use Lilja barrel which are made here in my home state, you know, support the local guys.

I have used several barrels from Lilja in the three groove design and have been extremly impressed buy them. Of Course, I have been extremely happy with every Lilja barrel I have every fitted to one of my personal guns or a customers. I feel they are as good a quality barrel as one can get from anyone, period.

I have tested the three groove barrels on several different calibers ranging from fast twist 22 caliber barrels to fast twist 6.5mm barrels.

What I have found is that on extreme velocity rounds such as my 22-6mm AI and 257 STW, the three groove barrels do seem to foul less and break in much quicker.

From talking with Dan Lilja about this design, he says not only does it foul less, but it engraves teh bullet jacket less resulting in less bore heat, and also resulting in a higher ballistic coefficient because the bullet is deformed less when it leaves the barrel from fewer rifling marks.

He also stated that velocity will be slightly higher with the three groove and loads will produce lower pressure compared to a conventional rifling design. How much is hard to tell but they have all worked fine for me.

I did have a concern with the three groove when I used one on my 6mm-284 fast twist with a Lilja 30" fluted #7 stainless blank.

I was going to shoot the 107 gr Sierra Matchkings and wondered how the three groove design would hold these long heavy bullets as they were launched at 3600 fps in a 1-8" twist barrel.

The range results proove that they perform great having fired several 1" groups at 500 yards.

I have also used these barrels on rounds such as the 257 STW firing the 100 gr Ballsitic Tips to 4000 fps and they also produced 1/2 moa groups out of a sporter weight rifle and barrel.

The only place I may not use a three groove design would be when using heavy short bullets such as the larger 375 rounds, 416 rounds and 458 rounds or larger. Interestingly, many of these larger bores are not offered in the three groove.

My opinion on these types of rounds is that I would prefer 6 or 8 rifling engraving the bullet to over come the heavy weighted bullets to get them rotating. There may be nothing to this theory but I would rather be safe then sorry for a rifle built around a serious working round.

For extreme accuracy work, I will select a Lilja 3 groove whenever possible.

Hope this helped a little!

Good Shooting!!!

50

Many U.S. M1903-A3 rifles were made with 2-groove barrels. They shoot just fine with jacketed bullets and cast. I used to play with one as a teenager. Wish I had it now!