Originally Posted by Bart B
'Tis not a theory; it's reality.
Some years ago an article in a rifle magazine explained it. Bead blasting creates more surface area than fluting a barrel. May not seem that way, but those micro sized mountains and valleys actually transfer more heat off the barrel than fluting does. Only 10% or so, but enough to be measured. The coarser the beads are, the more surface area will be attained.
I'm not one to worry about barrels heating up. Even shooting 1 shot every 5 seconds putting 10 rounds down range doesn't change point of impact if the barrel's made and fit correctly. They've got to be properly stress relieved and fit to receivers whose face has been squared with the barrel tenon thread axis. Folks have put 20 to 40 shots downrange about 20 seconds apart starting with a cold barrel and easily put all under 1/2 MOA at 600 to 1000 yards. Lake City Army Ammo Plant shoots a couple hundred rounds of M118 match ammo for accuracy tests fired about 20 to 30 seconds apart and good lots of ammo would shoot about 1 MOA at 600 yards; at 100 yards it would shoot about 1/3 MOA.
Factory rifles rarely, if ever, have squared up receiver faces; their barrels have one hard contact point around the barrel shoulder and when they expand from heat, stress at that point tends to make the barrel bend more in that general direction while the bullet goes through it.
The only bad thing about hot barrels is if the chambered round stays in more than 20 seconds seconds before its shot, the powder has heated up and muzzle velocity will be a bit faster and bullets will strike a bit high.
Good site on barrel fluting: The Real Benefits of Barrel Fluting
The cooling effects of bead blasting can be found in several web sites; search for "bead blasting barrel cooling" and pick one that's related to rifle barrels.
Thanks Bart B
In my short 30 years a shooting in the military, hunting, sporting and some competition and living with a brother-in-law that has probably taken close to 5000 non-contoured and contoured barrels blanks from Shilen, Kreiger, Hart, Lilja, Bartlien, Douglas, and Wilson and turned them into some of the most accurate weapons on the planet, I believe I can make a few comments here.
1st - around 80% of the guns my bro-in-law builds are fluted - he flutes everyone of them himself - except mine, I do those. I have NEVER seen one shoot bad because of the fluting - in fact, in some cases I've seen barrels shoot better after they were fluted, most likely not because of the fluting but because the barrel was re-crowned and in some cases re-headspaced and trued.
2nd - Bart B - you hit it on the head - truing an action and the bolt is the key - I've seen 416 Rigby's, 505 Gibbs, and 375 H&H's shoot sub 1/2 MOA @ 200yards with Dangerous game ammo (Barnes and Woodleigh solids) and the main reason was truing the action. Those cartridges are not "supposed" to shoot that well....
3rd - In a close second to truing the action is the process in which the barrel is threaded, chambered, headspaced, and crowned. If any of these steps are done incorrectly you'll most likely have issues.
4th - I believe that handloading is to blame for most accurracy issues, especially in a custom rifle
built by a competent Gunsmith.
After saying all of that, I believe that fluting has such a minimal effect on accurracy that it's not even worth discussing over other things that can seriously effect accurracy!
I know first hand one of the reasons that Shilen is anti-fluting - Law suits - I know of a Shilen barrel that was fluted by a wanna-be-gunsmith that came apart on a customer. The wanna-be-gunsmith fluted it to close to the bore and after the second shot it came apart. We all know what happened next - law suit against the builder and Shilen. How would you respond if you were Shilen?
For what it's worth.....