300 Win Mag barrel life?
- Thread starter markm87
- Start date
effendude
Gold $$ Contributor
I don't have any precise numbers but I am trying to keep better records on my new rifles. That said, I would guess that any magnum will give start giving up accuracy after a few hundred rounds. Whether that lost accuracy will be noticed is another matter. I plan to continue either rebarreling or selling my magnum hunting rifles after about 500 rounds. Accuracy is still good, but hunts are far more expensive than barrels!
Scott
Scott
fullersson
B&B Gunworks bbgunworks.com
http://www.6mmbr.com/gailmcmbreakin.html
In the above article Gale McMillan says the life expectancy is about 1000 rounds. Brian Brown.
In the above article Gale McMillan says the life expectancy is about 1000 rounds. Brian Brown.
jghoghunter
Gold $$ Contributor
I shoot a 300wsm and it started to go south around 1460 rnds and by 1600 rnds it was a 5" on a good day gun at 500 yds. Those are documented rnds and it would shoot 1-1.25 at 500 yds new.
One other consideration here; bullet weight. You didn't mention what weights will be the most prevalent here, but lighter weight bullets like the 150s to 165s will be a bit easier on the bore than heavyweights like the 210s-220s.
Hi Kevin....I have always thought that the smaller bullets in any cal ,,,not just 30,,,are harder on bbl life because you typically use a "faster" powder and/or more of it with smaller bullets ,,and the velocity is higher...I usually load everthing to MAX so the pressure would be the same......please correct me and my ignorance of the facts....Roger
expiper,
No, it's the heavy bullets that do them in faster, and I can base that on having washed out literally hundreds of barrels over the years in testing. To begin with, the chemical properties of "faster" burning powders are virtually identical to those of "slower" powders within the same line. A pound of IMR 4198 or 4227 has exactly the same amount of potential energy as does the same weight of IMR 4831 or 7828; they're chemically the same. The difference in the rates at which the energy is released is controlled by both powder geometry and very slight alterations in the deterrant coatings applied. But the bottom line is a grain of any of these (IMR single-base extruded tubular) powders has about 178 ft-lbs of potential enegry, regardless of its burn rate. So the flame temps are essentially the same. The other difference, pressure, is a separate topic, but can be altered higher or lower at our discretion. Let's assume for the sake of this issue that both heavy and light bullets are both being run at the same pressure, so that becomes a moot point. The real difference is in the inertia of the bullets. Putting it simply, the heaver bullet is harder to get moving down the bore when the shot is fired. This means all that high temperature flame and the highest pressures encountered within the bore, take place as the bullet is just mioving into the throat. It gives it the most opportunity to do its nasty work right there in the throat area before that bullet starts its movement further into the barrel. If you ever take a look at a barrel that's been washed out, this is the only area we normally see damage. The throat area will look like ten miles of bad road, while the rest of the bore, from just a few inches ahead of the chamber, will appear like new. Lighter bullets, on the other hand, get moving quicker, and get out of the area before all the really bad stuff takes place. They'll still cause erosion, but not nearly as bad, or as quickly.
Hope that helps.
No, it's the heavy bullets that do them in faster, and I can base that on having washed out literally hundreds of barrels over the years in testing. To begin with, the chemical properties of "faster" burning powders are virtually identical to those of "slower" powders within the same line. A pound of IMR 4198 or 4227 has exactly the same amount of potential energy as does the same weight of IMR 4831 or 7828; they're chemically the same. The difference in the rates at which the energy is released is controlled by both powder geometry and very slight alterations in the deterrant coatings applied. But the bottom line is a grain of any of these (IMR single-base extruded tubular) powders has about 178 ft-lbs of potential enegry, regardless of its burn rate. So the flame temps are essentially the same. The other difference, pressure, is a separate topic, but can be altered higher or lower at our discretion. Let's assume for the sake of this issue that both heavy and light bullets are both being run at the same pressure, so that becomes a moot point. The real difference is in the inertia of the bullets. Putting it simply, the heaver bullet is harder to get moving down the bore when the shot is fired. This means all that high temperature flame and the highest pressures encountered within the bore, take place as the bullet is just mioving into the throat. It gives it the most opportunity to do its nasty work right there in the throat area before that bullet starts its movement further into the barrel. If you ever take a look at a barrel that's been washed out, this is the only area we normally see damage. The throat area will look like ten miles of bad road, while the rest of the bore, from just a few inches ahead of the chamber, will appear like new. Lighter bullets, on the other hand, get moving quicker, and get out of the area before all the really bad stuff takes place. They'll still cause erosion, but not nearly as bad, or as quickly.
Hope that helps.
I've experienced exactly what Kevin is talking about. An older Shilen stainless 6BR 1-14, now with a documented 1720 rds. fired, since being chambered 7 yrs. ago. Fed nothing but 30 grs. of N133 with 68 gr. berger #24411, seated to touch. Bullet seating depth is only a few thousandths longer than when new, and the throat, as seen with my Hawkeye has no signs of firecracking. At the other end of the extreme, a Krieger stainless 6BR 1-8 with a documented 2000 rds. fired is "done". Fed nothing but 30 grs. of Varget with the 107 SMK's seated to touch. At approx. 1200 rds., could not touch the lands & keep a reasonable bullet/ neck contact: had to start jumping them. At close to 2000 rds., unexplained flyers began to be a problem, could not depend on it in a match, more copper fouling, & erosion & firecracking as seen with my Hawkeye. For those who claim a cut rifled barrel will last longer than a button rifled, this is one example where that is not true. Might be so if both were used with identical loads, including bullets, but that "rule" did not apply in this example.
Kevin ,,I agree that most powders within each manufacture is chemically the same and posses the same amt. of "power" per gr/lb etc,,,,and with a 200gr bullet typical charge wts are around 72gr and a 150 class bullet uses 78gr ....almost 10% more powder ....usually/always at the same operating pressure,,,,more powder is consumed/burned....although the MV is usually more (200 fps)with the lighter bullet....the first inch or so cant be much different....not trying to argue ,,,,just the way I have always thought about it....maby I need to get some book learning.....it culdnt hurt...ahhaha....you learn something every day.....thanks for the input....Roger
PS...most ppc's and BR' that I have had burn +/- .003" per hundred rds and the biggins (30 cal boomers) burn .004-.006...in my limited experience with em.....
PS...most ppc's and BR' that I have had burn +/- .003" per hundred rds and the biggins (30 cal boomers) burn .004-.006...in my limited experience with em.....
Expiper,
In one of the Sierra manuals (Third Edition, I think), I once wrote that it roughly takes "X" pounds of powder to wash out a barrel, but I was refering to different cartridges when I wrote that. My comparison in that example was regarding two "identical" barrels I had at the time, once chambered in a 6x45mm, the other in a 240 Gibbs. The barrels themselves were identical, same length, twist, material, etc., but chambered by two very different cartridges. The Gibbs burned a bit over double what the 6x45 did on every shot. I wasn't speaking of a few grains difference between the typical charge weights used in light or heavy bullets within the same chambering. Sticking with the same chambering, and all else being equal, yes, it's the heavier bullets that do the most damage in the least amount of time. Mid Tompkins once mentioned to me that AMU counted the lighter bullet loads they were using as 1 shot every time they pulled the trigger, but counted their heavy LR loads (80s and-at that time-90s) as 1.5 rounds for each trigger pull. Personally, I'd peg the difference as somewhat greater than those figures, but yes, it's something that I've seen many, many times. I still use heavy bullets for applications where they're called for, and accept the barrel wear as a simple fact of life.
In one of the Sierra manuals (Third Edition, I think), I once wrote that it roughly takes "X" pounds of powder to wash out a barrel, but I was refering to different cartridges when I wrote that. My comparison in that example was regarding two "identical" barrels I had at the time, once chambered in a 6x45mm, the other in a 240 Gibbs. The barrels themselves were identical, same length, twist, material, etc., but chambered by two very different cartridges. The Gibbs burned a bit over double what the 6x45 did on every shot. I wasn't speaking of a few grains difference between the typical charge weights used in light or heavy bullets within the same chambering. Sticking with the same chambering, and all else being equal, yes, it's the heavier bullets that do the most damage in the least amount of time. Mid Tompkins once mentioned to me that AMU counted the lighter bullet loads they were using as 1 shot every time they pulled the trigger, but counted their heavy LR loads (80s and-at that time-90s) as 1.5 rounds for each trigger pull. Personally, I'd peg the difference as somewhat greater than those figures, but yes, it's something that I've seen many, many times. I still use heavy bullets for applications where they're called for, and accept the barrel wear as a simple fact of life.
No argument there! That's why it's been around so long. 
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