Question: Does shooting heavy bullets reduce barrel life?

[davery25]

As per the title, I just want to know whether using heavier bullets reduces barrel life/accurate barrel life.

To be specific, I've been using 55gr projectiles in my .223 but i only ever shoot out to 100 yards. Once in a blue moon i might be bothered walking out to 200 yards but very rarely.

If i use 40 or 45 gr bullets instead, will that mean a longer barrel life or doesnt it matter. Keeping in mind lighter bullets mean higher velocity...

 

[necchi]

Interesting question and a good one, might not be as simple an answer as many may think. I look forward to more experianced answers too.

My take on it; It's pretty common knowledge "hot/fast" loads burn out a barrel sooner than mild loads, right?
So it wouldn't nessecarily be the weight of the projectile that adds to the equasion. However, heavier bullets force most guys into seeking more velocity to stabilize the bullet and help it preform further out.
More velocity = more or faster powder,,(?) Also bigger bullets have more bearing surface on the lands,,(?)
Hhmmm,?? interesting question,, :-\

 

[fa18hooker]

I'll throw my two cents in...no. Most 5.56 is loaded on the higher end of SAAMI specs (55k C.U.P.?), so going down to a lighter bullet (conceivably to get more velocity), burns even more powder than shooting a heavier bullet with less powder...but it's the heat and pressure that does the barrel in, so unless you're shooting those lighter bullets at the same or lower velocity than the heavier bullets you'll see no savings...and even then I'd say you're not gaining enough to make an appreciable difference.

 

[Klong]

My opinion is yes, if you are referring to heavy for bore size, or under size bullet diameter in relation to the powder capacity. I know of 223 Remington target rifles that have gotten accuracy past 6,000 rounds shooting 69 and 77 grain bullets with non max loads. the 220 Swift can't get anywhere near that with 50 grain bullets. 45-70 uses lots of powder and heavy bullets, but I have never heard of a barrel being shot out.

 

[fdshuster]

I had a conversation with Kevin Thomas about a year ago on this very topic and his opinion is yes, a long heavyweight bullet will contribute to barrel wear sooner than a short lightweight bullet. According to kevin it has to do with the longer bearing surface making contact with the surface of the bore. Hopefully he'll jump on here. After his many years with Sierra and now with Lapua I cannot think of many who are more qualified.

 

[RonAKA]

It is my view that barrel end of life occurs when the throat area is burned to the point accuracy is lost. For that reason I don't think bullet velocity or bullet bearing surface has anything to do with barrel life. The velocity is close to zero in the area that suffers the most, and the throat dies due to high temperature oxidation after the bullet has left, not when the bullet is leaving (wear). I also do not think pressure has any effect either. You can have very long life cartridges and very short life, and they are both loaded to the same pressure.

I would suggest the most key factors in determining barrel life is the weight of powder, and the area of the bore. More powder, less area, more burning. This probably could be refined somewhat by considering the energy density of the powder as well as the weight. Double base powders tend to have more heat density, so for the same weight of powder produce more heat and burning. And another factor is time duration of the heat, which is approximated by barrel time.

Lighter bullets take more powder and thus there is more heat available to burn the barrel. But, the barrel time is likely less, so that may or may not make up for the additional heat. If you use Quickload a simple approximation may be to multiply barrel time times the powder weight to get the relative effect. Probably close to a wash.

There may be some advantage in using a single base powder if it achieves your velocity goals. Just less heat, and duration of heat. I also think there may be a small advantage in using a bit faster powder (and less of it), if it meets your velocity goals.

Just my thoughts,

 

[necchi]

"It is my view that barrel end of life occurs when the throat area is burned to the point accuracy is lost."

Sure, but don't guys adjust for awhile but seating deeper as the throat errods? Then, with custom barrels, mill the end and cut the chamer a bit deeper to compentsate ?
Sooner or later the lands are worn out too,,,

 

[bozo699]

My thoughts would be like this, ( not based on scientific facts ) just my thoughts,
Heavier bullets would wear the bore (riflings) out quicker due to bearing surface . If you were asking what causes more throat erosion I would say lighter bullets because you have more of and faster burn rate powders causing extreme heat in the throat area. The barrel calculator I got off this site go's by,
#1 cal.
#2 amount of powder
#3 powder heat potential (formula)
#4 cup pressure (default 55000 psi )
#5 Moly coated bullets or not

If you go by the calculator alone, it would appear that there mostly concerned with throat erosion since to moly or not is the only thing that would concern rifling life. does this make any sense?
Wayne.

 

[Shynloco]

Personally, I tend to agree with RonAKA's response. And given the slight weight difference you listed, I seriously doubt that your barrel is gonna wear out any faster whether you use 55 grs, 52 grs or 45 grs. Besides, you are talkin alot of firings before you have to worry about barrel burnout. My concern would be more in the accuracy area. If you find the bullet your barrel likes the most and you get ultimate accuracy, I personally wouldn't worry if I burned the barrel out at 8,000 rds or 10,000. Besides, barrel replacement is no big thing in most weapons when done by a competent Smith or even gun owner.

 

[fivering]

A far bigger factor in barrel life than bullet bearing surface is the amount and velocity of the 5000 degree plus hot gas jetting down the rifle barrel.
As larger powder charges are used with lighter bullets, and they go down the barrel faster than heavy bullets, it stands to reason that hot varmint type loads will give less barrel life than hot target loads with heavier long range bullets.

 

[RonAKA]

#5 Moly coated bullets or not

Harold Vaughn in his book Rifle Accuracy Facts, has some interesting thoughts about moly coated bullets. It is well known that moly reduces velocity, and it is commonly assumed that is because the moly reduces the friction in the barrel, and that in turn reduces peak pressure. So most increase the powder to compensate, and restore the velocity.

Vaughn argues that a reduction in friction does not explain the velocity reduction, and what really happens is that the moly is vaporized by the heat, and this reaction reduces flame temperature and pressure. He accepts this may increase barrel life if you maintain the reduced velocity and pressure, but I recall also argues if you crank the powder up to compensate, you are back to square one, and have gained no value in using moly.

I don't have the book any longer, but I think that was the gist of it. My take away was that I was not going to bother with moly.

 

[KevinThomas]

Davery25,

The answer here is yes, heavy bullets do wash out barrels faster than lighter ones, all else being equal. A complex equation going on here, but having shot out scores of barrels over the years, its been my observation that in any caliber, in any chambering, the use of heavy bullets is harder on barrels and gives shorter accuracy life than does a lighter bullet. In the example you're talking about here, a 55 vs a 45 grain bullet, I think the difference would be hard to discern. A comparison between the 50-55 against the 77 to 80 grain bullets is the sort of difference I'm referring to here.

Frank mentioned our conversation from a time back, but he's a bit off on what I said about friction. I think that has little (if anything) to do with this phenomenon. I suspect it has everything to do with dwell time, i.e., how long the bullet spends getting off the throat/leade upon firing. Basically, the longer, heavier bullets have more inertia, and it takes more to get them moving down the bore. This translates to a slightly longer time that all that hot gas is in the throat area, all the while doing its inevitable damage to the throat. Sectioning a shot out barrel, or even looking at one through a borsecope shows this quite plainly. The area ahead of the throat is very badly cracked and eroded, while from this point forward the barrel will look virtually untouched.

The flip side to this is that the heavier bullets offer better performance at distance, and hence are the logical choice for such applications. No such thing as a free lunch, and when you need the performance, you have to match the bullet/load to that application. Don't get attached to your barrel; they're strictly a replacement part, temporarily attached to your action. They're expendable, and the only way to not wear them out is to not use them.

Kevin Thomas
Lapua USA

 

[bozo699]

The flip side to this is that the heavier bullets offer better performance at distance, and hence are the logical choice for such applications. No such thing as a free lunch, and when you need the performance, you have to match the bullet/load to that application. Don't get attached to your barrel; they're strictly a replacement part, temporarily attached to your action. They're expendable, and the only way to not wear them out is to not use them.

Kevin Thomas
Lapua USA

Truer words were never spoken!
Thanks for your input Kevin It was very well written and I learned from it.
Wayne.

 

[RonAKA]

It would be interesting if someone with Quickload did a comparison of light bullets, medium weight, and heavy bullets in a cartridge, and just multiply the powder charge weight times the barrel time for each. It may be true that charge weight goes down less than barrel time goes up, and the net effect is more heat duration for the heavy bullets.

 

[Travelor]

If I remember correctly (yeah, good luck with that), the NRA did a test one time concering the accurate barrel life of a 30-06 Springfield barrel firing Ball vs. Armor Piercing (AP) ammo. If I remember correctly again, the test found the AP ammo gave a better barrel life. I believe the AP bullets weighed more and has a longer bearing surface.

My thoughts are that a lighter bullet loaded with more powder will hasten the barrel life as opposed to a heavier bullet with less powder. i.e. the heat generated by the combustion of the powder wuld be higher/more intense.

Just my memory of a test in the past.

George

 

[Travelor]

Found a reference to a US Army test Ball Vs Match heavies
apparently written by Dick Culver.


"The short answer (as you have apparently just found out from personal experience) is that your barrel should be good for another 5000 rds (at least according to a Frankfort Arsenal Report conducted in the 1945/1946 timeframe.
Old wives tails had long held that a maximum barrel life with service ammunition was approximately 5000 rds or less. Some said as few as 3500. And just EVERYONE knew that using AP would trash your barrel in a heartbeat. On the flip side of the coin, most experts considered that M1 (172-gr) Ball, (essentially a precursor of the 172-grain FA Match 30-'06) to be extremely accurate, however according to urban legend, it was BOUND to "eat" barrels at an accelerated rate due to the 9 degree boat-tail that would allow hot gasses forward of the bullet base while the projectile was still in the bore!
As it turns out, virtually every old wives tale was pure unadulterated "Moose Manure", however some very high priced help published them as gospel. Clark Campbell in his excellent book "The '03 Springfield" parroted the widely held belief concerning the 172-grain match ammo being hard on the bore, and Phil Sharpe, one of the developers of the .357 Magnum Cartridge an a WWII Army Ordnance Officer and regular contributor to the "Dope Bag" in the American Rifleman) put out the information in his "Complete Guide to Handloading" that while the mild steel jackets of the WWII .30-'06 Ball wouldn't harm the bore of your favorite target rifle, he would not shoot .30 caliber M2 AP in his rifle under ANY circumstances... Just goes to show you how wrong you can be.
Frankford Arsenal grew weary of the stories and decided to conduct a test to determine if they were correct. Without going into great detail, they found that when using either M1 Ball (almost identical to the later M72 Match Ball) or M2 Armor Piercing, the accuracy actually improved up through the first 1000 rounds or so (don't hold my feet to the fire on the exact numbers as I don't have my references in front of me and am too lazy to dig 'em out right this second). They continued to fire the test (using a test rack) and it seemed that the accuracy "improvement" seemed to taper off after 1000 rounds, but the accuracy itself did NOT decrease. The accuracy continued to be excellent to outstanding through at least 8000 rounds. They finally ceased the test, not because the accuracy was declining, but because they simply got tired of firing, since the accuracy showed no sign of decreasing. FA estimated that the excellent accuracy should continue through at least 10,000 rounds and probably beyond.
This was NOT the case with the 150 grain M2 Ball however, it seems that the accuracy began to drop off after about 3500 - 4000 rounds (again don't hold my feet to the fire, I plan to write an article on this and will include the actual figures when I do). The only common thread to the barrel longevity I can personally see, is that both the M1 Ball (172 gr. Match) and the 165-168 gr. AP have a boat-tailed configuration (9 degree for the 172 and a much less obvious 6 degree for the AP).
Throat erosion is another bugaboo that is usually blown out of proportion. We had a gent by the name of Eric England shooting for the Marine Corps for years. He had a favorite M70 that the Ordnance folks kept trying to get him to turn in since the throat was essentially non-existent... Eric steadfastly refused because he kept setting National Records with a shot-out throat... An old rule of thumb used to be that two things happened if your bore was shaped like a pyramid (i.e., bigger at one end than the other). If it was big at the muzzle and small in the throat, you had a boat anchor. If it was big at the throat and small at the muzzle, you had a (potential) shooter - please understand that I'm talking "relative measurements" here... In other words, if your muzzle was tight you were usually OK, but not the other way around.
At any rate, I've raved on much further than I had planned, but I think you can plan on an extremely long accuracy life out of your M1 or M1A barrel if you continue to use 168 -175 gr. boat-tailed bullets at normal velocities…
Best regards,
Dick Culver"

 

[KevinThomas]

Travelor,

We're comparing apples and oranges here, or at least, not speaking the same language for the comparison. The difference between 150 and 172 is relatively minor, and while this weight of bullet is considered heavy in M1s and M14/M1As, it's a mid-weight bullet compared to those used in bolt guns; 190s and above. Compare the 190s or 200s to that same 150 grain bullet and you'll see a pronounced difference in barrel life. I also have to shake my head a bit at the figures they're listing here, as they speak of match winning scores. During this period, that would have been the old 5-V target, which isn't nearly as discriminating as our current decimal target. The numbers he cites are wishful thinking on the current target, nothing more. By military definitions of barrel life, 10,000-20,000 rounds may be viable. In some of the older texts I've read on this matter, they regarded a barrel as shot out when bullets begain keyholing or tumbling. For match accuracy, or even hunting accuracy, it's a whole lot shorter. For my own uses, I expected 3,000-3,500 rounds out of a 308 Win, and usually saw a measurable degradation in accuracy right around that mark. Saw some that went a bit less than this, and a few rare exceptions that went to 5,000 rounds or so. All things are relative here, and that's what I found for the barrels I was using in accuracy testing. Couldn't use them for that purpose any longer, but a hunter might have been thrilled with these for another 5,000 rounds or so. For a benchrester, even shooting light weight bullets, most consider the barrel gone in 1,000 rounds, some even less than that. And that's with a small cartridge (6mm PPC) and a very small amount of powder. Their standards and requirements are simply different. I suspect that's the same thing we're seeing here.

Kevin Thomas
Lapua USA

 

[jonbearman]

I read the article that the nra put out and the test was if a barrel were broken in with ball vs armor piercing and which would yield the best accuracy.Guess what,the one shot initially with the armor piercing shot the best.The question was a result from a member saying ap ammo would ruin the rifling and would make the barrel less accurate.It appears the copper coated steel armor piercing made the barrel shoot better with the ball ammo after being broken in with that type of ammo.

 

[necchi]

I read the article that the nra put out and the test was if a barrel were broken in with ball vs armor piercing and which would yield the best accuracy.Guess what,the one shot initially with the armor piercing shot the best.

Not to denie or argue those results, but what was the logic/reason behind that ? Did anyone come up with WHY the AP did what it did to the barrel ?

The idea that AP will harm your barrel is still out there,,alot!

 

[Travelor]

Mr Thomas, I was not expressing my ideas by copying the article, just presenting what has been done in the past for a comparison.

I certainly bow to your experience. I too shoot 308 in NRA matches and we have found they are about "toast" at 3500 rounds for match accuracy with the 155 gr Plama bullets.

George