How many lands and grooves?

[gondorian]

So what determines how many lands and grooves will be in a barrel? What determines the optimum number for a caliber? I'm just wondering because my .22 has 16 groove rifling and my Garand has four, but barrels with 6 grooves can be had for it. ??

 

[Nugilum]

I know that the M1903A3 from WWII only has two groves. Military tests have shown that the two groove barrels were as accurate as the four groove barrels.

 

[Jim Watson]

The "optimum number" of grooves for a barrel usually depends on your prior experience. If you have had a good shooting 6 groove barrel, you will probably get a 6 groove barrel to replace it. There are a lot of factors affecting accuracy, velocity, and barrel life and the number of grooves is not a big player.

By the way, Nuglium, the 03A3 will be found with 2, 4, or 6 groove barrels, depending on the maker and the time frame.

 

[Ignition Override]

Some WW2 Lee-Enfield #4s only have two grooves.
Have read that it did not affect accuracy.

These might have been all of those which were built by Savage (for the British/Commonwealth forces).
Most LE #4s were built in North America: Savage or Longbranch (Canada).

 

[madcratebuilder]

The LE's had eight different .303 variations of barrels in 2, 3, 4, 5, and 6 groove. Most Brit barrels are 5 groove and most North American barrels are 2 groove and have comparable accuracy.

The Brits produced just over two million LE's while being bombed and rocketed, North America produced about 120,000 more in a shorter time frame but under much better conditions.

 

[Slamfire]

If you notice most barrels have even numbers of grooves.

I suspect that is due to manufacturing and inspection. I would think an even number of grooves is just easier to cut, or the cutting tool is not loaded unevenly. But this is just a guess.

As for inspection, it is very easy to measure across on a even number of grooves, odd grooved barrels would require special devices.

I have shot lots of 308 four groove and six groove Douglas barrels. Can't tell any difference on target. I have a number of four groove Kriegers. They shoot well, though Krieger barrels are tight and require cutting the load compared to the Douglas barrel.

Marlin microgroove barrels, which I had three on my M1894 did not shoot cast bullets worth a flip. Cast bullets leaded at too high a speed. And their barrels were poor quality. My first barrel showed circular tooling marks and had tight spots. I do not have a high opinion of microgroove barrels.

However the Ballard barrel Marlin installed is very high quality, smooth all the way through.

 

[paducahrider]

What determines number of rifling grooves?

Howdy!
I believe that it's probably a combination of, trial and error, performance and cost.
There are many combinations which have been proven to work equally well.
Some are easier/cheaper to produce than others.
I agree with Slamfire about the microgroove Marlins. They should stick with the Ballard rifling on everything.
THanks for your time.

 

[MachIVshooter]

Marlin microgroove barrels, which I had three on my M1894 did not shoot cast bullets worth a flip. Cast bullets leaded at too high a speed. And their barrels were poor quality. My first barrel showed circular tooling marks and had tight spots. I do not have a high opinion of microgroove barrels.

I've always liked the micro groove tubes. They seem to promote slightly higher velocities (like poly barrels). But then, I've never shot cast bullets through them (not supposed to anyway)