Bullet speed versus barrel wear

[Coltdriver]

So as I get into reloading I have acquired some ballistics software.

According to the software for a .223 shooting a 40 to 50 grain bullet I have to get the muzzle velocity up around 3400 feet per second to get it to shoot about 1.5 inches high at 100 yards, zero at 200 yards and then somewhere around 1.5 inches low at between 240 and 260 yards.

That is a fairly stout load for the .223 cartridge. At those speeds with IMR 4895 it is a compressed load and the primer, although not quite "flowed out" is very close. Brass stretch occurs with this load every time. No other adverse effect to the brass, the concentricity is ok, no splits or bulges.

So my question is this. Any ideas how long the barrel will last with a load going out at that speed???

Is there a muzzle velocity where extreme wearing occurs? I have heard of 220 swift barrels lasting only 2000 rounds.

Anyone got a lot of experience with a .223 and these velocities?

 

[wingman]

I am no expert on this however I will tell you some years back I did reload
for both the 22.250 and 223. I seen some accuracy loss in the 22.250 after
2000 rounds however the 223 was still super good at 2000. I also had
better accuracy from the 223 with less then max loads. if I remember
correctly somewhere around 3200fps.

I just dont see the 223 burning out a barrel as fast as a 22250 or220swift.
unless of course we are talking rapid fire(hot).

 

[Peter M. Eick]

I have been told and read that it is more a function of the pounds of powder you fire then anything else.

Lets say your barrel is good for 10 lbs of powder (just guessing by the way) and you shoot it out in 70 grn loads. You would get 1000 shots before the barrel was burned out. Less say you shoot it out in 7 grn loads, now you get 10000 shots before it is burned out. See the issue? More powder burns hotter and longer.

Also think about it. What fails first back by the breech where the bullet is traveling slow and the powder is the hottest or out at the end of the barrel where the bullet is the fastest but the powder has cooled off relatively. It is almost always back at the breech where the throat is burned out.

 

[EchoSixMike]

Heavier bullets cause more wear than light bullets. That's due to the pressure/heat being of lesser duration with light bullets vice heavy bullets(due to inertia and graving resistance). It's the heat/pressure that causes throat wear(which is what kills barrels), not projectile friction. S/F...Ken M

 

[Archie]

Like EchoSixMike said...

It's the heat/pressure...

One can rub gilding metal on steel all day and not wear out the steel. It's the heat of the powder burning that causes wear. The burning temperature is as hot as a cutting torch, but only for an instant.

Burning temperature is related to pressure. The more pressure, the hotter the flame temperature.

So, to extend barrel life:

Use slower burning powders that spread the pressure out and therefore don't burn as hot. Load as low as you can to achieve your goals.

Space out your shots. Rapid fire causes the internal surfaces of the barrel to heat up and become more suseptable to flame cutting. Let that barrel cool down. Swab it out with a patch and some solvent every few shots to aid cooling.

 

[Coltdriver]

Archie are you saying that faster burning powders are hotter than a slower burning powder??

I was looking at my Lymans 48th and I compared the powders they offered loads for.

It was interesting that on the scale of relative burn rate they used powders that fit in a range from about 61st (IMR 4198) all the way up to about 80 (Varget).

It is also interesting to me that the heavier the bullet the trend goes toward slower powders.

What is the logic there?

Do you know what is the actual measurement that gives a powder its burn speed?

 

[Peakbagr]

Its not really the bullet speed that wears out barrels.
Its the large powder amounts being burned to push a bullet VERY fast and the high temperatures the the barrel throat is exposed to that wears out the accuracy in barrels.

a .220 Swift all by itself doesn't wear out a barrel. Its the powder necessary to achieve those fast velocities that does it.
If you downloaded the Swift to 3,400 fps, they'd last as long as a .223, but then you wouldn't have the performance your got the Swift for in the first place.
Benchrest shooters generally feel about 1,800 to 2,000 rounds is about the competitive life of a high quality match barrel before it becomes a practice or fireforming barrel.

 

[caz223]

Yup, given proper loads, and proper care...
For my .223...
I load a 45 grain hornet bullet at 3400 FPS, and it will outlive me at my current rate of shooting...

 

[wanderinwalker]

Coltdriver,

Regarding the slower-powder/heavy-bullets in the .223, MY experience (backed up by others) has been that powders like H4895 and Varget allow for more velocity than W748 (a "standard" .223 powder) at safe pressures. I'd tell you how much of either Hodgdon powder I can safely cram in, but I'm not sure exactly how much that is! Temps around here lately have been so cold I could probably fill cases to the top, cram bullets on, and STILL have safe loads! (Not a recommended practice by any means. Do NOT attempt to do this! )