Barrel burners...where is the velocity threshold???

[saturno_v]

We all know that there are "barrel burner" calibers such as 264 Win Mag, 22 Swift, 204 Ruger, 300 Wby, 30-378 Wby and so on...

Some of there cartridges are notorious for their very short barrel life (in terms of rounds fired) despite special treatment in the manufacturing.

All of them develop MV well over 3300 fps.

On the other side you never hear of excessive barrel wear even after thousands and thousands of rounds in more normal, still fast, chamberings such as 30-06, 270, 223, etc..

Of course barrel wear increases if you shoot repeatedly without letting your barrel cool.

So what is the "threshold" in velocity when your bore erosion increases significantly?? Around 3000-3300 fps for regular barrels short of exotic materials and treatment??

There is any significant difference in barrel wear, let's say between a 30-30 and the faster 30-06???

 

[matrem]

That may be more an issue of powder "heat" than velocity.
Bbl steel won't care about velocity..Temperature..Certainly.

 

[Horsemany]

Velocity is only a part of the equation. It's the amount of burning powder being squeezed into a small diameter bore.

 

[Art Eatman]

Yeah, the erosion of the leade, that portion of the barrel immediately in front of the chamber. The entrance to the barrel.

Odds are that something like a .460 Weatherby is hard on the leade, but I'll leave that little exploration to somebody else.

 

[748]

Some of the real crazy high speed guns shoot wild cat rounds not limited by SAAMI.
All the powder is burned once the bullet has traveled 2 or 3 inches down the barrel in a rifle.
This has a sand blaster effect on that part of the bore.
A standard round like a .223 or 30-06 work on 50,000 to 55,000 psi. These last a real long time.
Your hotter rounds like the WinMag and WbyMag use up to 65,500 psi and are known to ware out faster.
Brass fails some where around 80,000psi the gun its self - some where around 150,000psi.
The few and far between guns you hear about that ware out after 1500 shots or so have to be pushing the brass to nearly its failure point and the bullets to over Mach 4.

 

[rangerruck]

you can't just go by velocity, bore size is huge, pressure is huge, and case design is even huger-er. for instance, a 6mm remmy is not considered a bbl burner. Why? case design; even though it is faster by 300 fps , a normal 243, and even though the case is long and skinny, which is a no-no, the neck is extra long on them. This gives the burning powder plug a chance to burn all up, and even if not burn all up, cool down significantly , before it makes it into your bbl throat. That is why short , fat, cases are great at burning up all the powder/plug before going into the throat. better volume/geometry/gas expansion and burn, in a fat wide diameter case, than a tall, long , skinny, case.
then of course, a skinny diameter bore, doesn't help with gas expansion, air flow, etc., so a bigger bore is more efficient at helping to burn up the gas, and cooling it off, and getting more air into the burn area, into and before the powder plug leaves the case, etc.

 

[1858rem]

i didnt think the .204 ruger was a barrel burner? something about the way the .222mag is designed helps with preventing throat erosion or something....sticking within normal loads anyhow at around 4100 fps and not much more than 58,000psi......about the same as a .308 pressure range right?

 

[redneck2]

As a general rule, a 10% increase in powder capacity gives a 2 1/2% increase in velocity for a given bullet. The other 75% of the powder that doesn't push the bullet faster creates enough heat to scorch the metal.

Typically, the larger the case and smaller the bore, the more heat is forced through a smaller area. As noted, the gases have less time to cool and less metal to absorb the heat. The hot gasses exiting the barrel give muzzle blast. I suspect there's a pretty direct correlation between muzzle blast and barrel life.

The uber magnums are great for impressing impressionable guys at the gun shop that talk a lot and shoot a little. If you talk to most guides out west, they cringe every time they see a newbie show up with one.

As to the velocity threshold, I suspect any time you exceed the 3,500 range you're looking at the potential for excessive barrel wear. I'm going on a PD hunt and taking a ,223 and 22-250 among others. The 250 will heat way faster than the .223. About 3,850 versus 3,250 fps

 

[Horsemany]

As to the velocity threshold, I suspect any time you exceed the 3,500 range you're looking at the potential for excessive barrel wear. I'm going on a PD hunt and taking a ,223 and 22-250 among others. The 250 will heat way faster than the .223. About 3,850 versus 3,250 fps

I've noticed the same thing. The 223 is certainly more efficient burning only 2/3 the powder as it's big brother. I think that has more to do with barrel life/heat than speed. There's a noticeable difference though in how big of a red cloud on can make of a prairie dog. Especially at distance the 250 really shines IMO.

 

[Jim Watson]

I don't think there is a precise velocity thresshold, it is more, as said, how much blazing powder is being funneled down a small hole.
The 6.5x284 is a popular Long Range caliber because it fires a high BC bullet at high enough velocity to minimize wind drift without the heavy recoil of a Magnum. The accuracy "sweet spot" is often given as 2950 fps, although the maximum velocity is around 3100 fps. This round is well behaved in all respects, easy to load for, easy to shoot, but has a barrel life (for accuracy at 1000 yards) of perhaps 1200 - 1400 rounds.

 

[USSR]

As has been already stated, it's not all about the velocity, per se. Actually, it's more of an amount of powder to bore size factor. For example, both the .30-06 and .300 Win Mag can send 190gr bullets at 2900fps with RL22 powder. But, the .300 Win Mag uses about 12 more grains than the '06 to do it. So, with all other things being equal and using these loads, we can expect the '06 to have a longer barrel life. Also, the type of powder used has an effect. Using single based powders instead of the nitroglycerine-laced double base powders will help to prolong barrel life. Also, case neck length as previously mentioned will have an impact as well.

Don

 

[Art Eatman]

USSR, a question about "Using single based powders instead of the nitroglycerine-laced double base powders will help to prolong barrel life."

(I'm no chemist.) I thought one reason for the demise of the old Hercules HiVel line of powder was that because they were single-based, they burned hotter than the DuPont IMR's double-base powders. At least, that's the memory I retain from reading about it in the late 1950s or thereabouts.

 

[Jim Watson]

Other way 'round, Art.
All DuPont IMR powders and the preceeding MR powders were single base, nitrocellulose only.
HiVel No 2 is a double base powder containing nitroglycerine.

When the trustbusters got to DuPont for monopolizing the powder and explosive business 1907-1913, the company was broken up with the gunpowder business being divided roughly by composition. DuPont kept the single base powders, Hercules got the double base. Maybe there were exceptions but that was the general alignment.

 

[Ridgerunner665]

Overbore...squeezing hot, high pressure gas through a small hole.

Increase any of those (temp, pressure, overbore) and you get a barrel burner)...

Its not based on velocity per se...its just that it generally takes overbore to get really fast MV's.

In simple terms...it works just like an acetylene cutting torch...hot burning gas forced through a small opening....the smaller the hole, the "sharper" it cuts.

 

[R.W.Dale]

In simple terms...it works just like an acetylene cutting torch...hot burning gas forced through a small opening....the smaller the hole, the "sharper" it cuts.

Yes and this opens the door for another cutting torch similarity I would like to make as it relates to proper barrel care.

If you've used a torch enough you'll likely notice that a rough course imperfect surface on the material being cut will absorb the preheat and come up to cutting temp much faster than a smooth surface. I firmly believe the same principal applies to ill cared for throats where copper is allowed to build up it gives the high pressure gas that heat concentrating edge or surface and exacerbates throat wear as a result.

I'm convinced that with today's powders shot through properly cared for modern stainless barrels that the traditional concept of a barrel burner can be rendered a thing of the past

 

[Ridgerunner665]

I'm not sure I'd call it a thing of the past...but I'll agree, its not as bad as it once was.

 

[IndianaBoy]

It's somewhat an overblown issue. My 220 Swift bore is in great shape.

Sustained strings of fire when the barrel is already very hot will erode the lands. Keep the barrel cool and it won't be a big issue.

 

[feets]

One of my preferred loads for the 300 WM had 190 SMKs moving at 3100 fps. The barrel soaked up over 1000 of these loads along with 800+ other loadings.
There's no sign of degrading accuracy despite the high number of hot loads.
Changing powders but keeping the same muzzle velocity would move the heat around in the barrel.
IMR powders would heat it up just in front of the chamber. Hogdon powders would move the hot spot nearly two inches farther down the barrel. I'm pretty sure that's a good sign of where the pressures are highest outside the chamber.

The fastest shooting I've ever done with it was at a couple matches where we had speed dots. 20 seconds to make 5 separate 1" bullseyes at 100 yards. That got the barrel hot.
Not only is that tough to do with a long action holding 3+1 in the magazine but it's also hard on the barrel. I try to keep away from that kind of abuse.