Barrel life difference between a parent cartridge versus a wildcat from it?

[Hygienist]

I'm considering building perhaps an AR10, either in 6.5mm Creedmoor, or a wildcat of it, the 6mm Creedmoor.

From the 6.5 Creedmoor, I'd be shooting a 140gr Berger VLD at presumably 2600 FPS.

From the 6mm Creedmoor, I'd be shooting a 115gr DTAC at presumably 2850 FPS.

Am I going to see a significant difference in barrel life here? I know 260 Remington vs 243 Winchester, the 260 has better barrel life, but does that apply here since these two are pretty much using the same brass?

[MistWolf]

All else being equal, the smaller the bore diameter, the greater the throat erosion

[Clint]

Rate of fire and therefore barrel heating seems to be one of the major factors in barrel life.

Velocity seems to play a role in barrel heating too.

IMO, it is unlikely the average use will wear out any barrel, especially an expensive wildcat. YMMV.

[The_Hammer_Man]

+1 to what Mistwolf said.

The two places a wildcat chambered barrel erodes first are the chamber throat and the crown.

Whether or not it will wear out faster then the parent cartridge is debatable. IMHO your barrel's service life is related more to what company cut your barrel and to what tolerances.

In my experience uber-tight match barrels have a service life of about 5-7k rounds. This number is , of course, mitigated by barrel material choice and how it is rifled. (Cut/Button/Polygonal.. ETC.)

Hope this helps.

[BobinNC]

I'm considering building perhaps an AR10, either in 6.5mm Creedmoor, or a wildcat of it, the 6mm Creedmoor.

From the 6.5 Creedmoor, I'd be shooting a 140gr Berger VLD at presumably 2600 FPS.

From the 6mm Creedmoor, I'd be shooting a 115gr DTAC at presumably 2850 FPS.

Am I going to see a significant difference in barrel life here? I know 260 Remington vs 243 Winchester, the 260 has better barrel life, but does that apply here since these two are pretty much using the same brass?

The 6.5 Creedmoor will push a 140 Berger VLD considerably faster than 2600. I've seen velocities from bolt 6.5 Creedmoor's top 2750 FPS. Further a 6.5 mm 140 VLD will have a G7 BC 0.323 vs the 115 gr DTAC G7 BC 0.274.

That means considerably better flight characteristics at long range. And long range performance is where it's at with these two rounds. Always remember velocity is a wasting asset, but BC is forever.

As to barrel life, a 6.5 Creedmoor will have a longer barrel life than a 6mm Creedmoor. How much longer, hard to say,. But experience tells me the useful (still providing match accuracy) barrel life of a 260
is around 3000 rounds (+-500). A 243 Win is around 2,000 rounds (+-500). Since the 6mm Creedmoor is no more than just a necked down 6.5 Creedmoor I would expect it's accuracy to that much less (around 1000 rounds less) than whatever you could get from a 6.5 version.

Since your planning on an AR10 I presume that speed of fire is important. If it wasn't you'd be better off with a precision bolt action. If that is the case, rapid fire can burn out a barrel quicker than my estimates.

A good 308 Winchester barrel will last a upwards of 6000-8000. A 7mm08 will be less at around 4000-5000. A 260 max's out at around 3000-3500 or so. A 243 Win at 2000 to 2500.

All four cases have almost the identical case capacity, but when we blow hot gases through the smaller bore the erosion effect shortens the life of the barrel.

Who chambers it really does not matter. Whether you have a match chamber does not matter. Whether the barrel is cut rifled, button or hammer forged means little. All that matters is how fast you fire it, and how much powder and hot gases, in relation to the size of your bore.

Bigger the bore the better your barrel life. The smaller your case the better your barrel life.