just wondering. I shoot alot of 22-250 and .223
THANK YOU!!!

not an expert but my guess would be it's not the powder but the number of bullets at 3000+fps going down the barrel is what actualy decreases rifling in a barrel.

I read in a past Rifleshooter that the slower powders burn up barrels faster, but high speed will do it also. Jay

cleaning regimen and patience when shooting play a far greater role in bore erosion. However,..I would venture a guess that slower powders take longer to erode a bore due to slower burn rates and subsequently lower temps at the throat. just a guess.

Since everybody else is venturing a guess, I'll venture one too: slow.

What matters is primarily how long and to what extent the barrel just in front of the chamber will be heated. I think a slow powder will burn longer, and thus heat the barrel more - given the same amount of powder burnt. To verify this, we would have to see curves for barrel heat as a function of combustion temperature and duration.

In addition to that, I think slow powder stands a chance of excerting an increased mechanical influence on the barrel just in front of the chamber, through the larger granules of powder getting blown at the barrel at high speed.

My guess: slow.

- mike

My take is that the #1 cause is rate of fire. As to the burning rate of powder I would say the slow ones only because they are the appropiate ones for over bore cartridges.

It's not the speed of the powder, it is the speed of the shooter, especially in over-bore cartridges.

All powders essentially reach the same temperature and the gases reach the same velocity. But, if you cannot place the tender side of your wrist on the barrel without discomfort, you are shooting too fast ... and that is what causes barrel problems. (But my personal opinion is that more barrels are ruined by improper "cleaning" methods than by any other factor.)

trashcanman:

I've had the opportunity to watch a large number of barrels with a decent borescope. To directly answer the question as you posed it I was never able to see any difference in throat erosion from different powder speeds. However, different powders did erode differently in the same chamberings and in the same barrel for that matter. My friends and I concluded that the coatings on the powders may be a contributor. We also concluded that the volume of the powder, the pressure of the round, and the rate of fire were major contributors.

knobmtn

VERY generally speaking, and all other things being equal, double base powders burn hotter than single base powders. Of the double base powders, again speaking VERY generally, ball powders are the hottest (one notable exception is W748). For example IMR4227 (single base) is very much cooler than H110 (or W296) both double base ball powders.

Of course there are exceptions. Older powders within there general composition (single or double) typically burn hotter than newer powders, for example, IMR4895 is considerably hotter than IMR4064, at least in my rifles it is.

ASS_CLOWN

I was just reading (for the umpteenth time) part of my Sierra reloading manual. They mention that the flame temperature of powders with high nitroglycerin content is higher, and results in greater bore wear. That means double base powders should wear faster than single base. Now I remember a lot of double base powders being advertised as 'lower flame temperature', so maybe chemistry has overcome this problem...???

Barrel temperature and rate of fire are well documented major contributors to throat erosion.

Listen to what ASS_CLOWN, Steve, and savage99 have to say. They are all right on the money. Double base powders will wear out your bore faster than single base powders (again, very generally speaking) FOR A GIVEN RATE-OF-FIRE. As for rate of fire, as it increases, barrel life will decrease. As far as the double-base pwoders go, I know a BR shooter that has been in competition with a 300WM for 30 years now and has gone through many barrels in his precision rifle. He says RL22 (double base) reduced barrel life by 300 to 500 shots as compared to H4831SC (single base). However, I like RL22 with some loads and it is accurate so I don't care. Heck, my barrel is going to last 3000 rounds anyway in my 270, I would love to burn that thing out faster so I have another excuse to build another custom rifle! I will keep using RL22 (outstanding double base powder) where it is more accurate than my H4831SC (which I try to use more often) in my 270 and 300WM. For your 22-250, varget, H4895, and H380 are excellent single base powders, and the first 2 are fairly temperature insensitive. Use these or any other single base powder that is more accurate than these (I am almost 100% positive you will find one of these 3 to be outstanding!!) for a 1-14" or 1-12" twist rate barrels, or use IMR4350 in a fast twist (1-9" and 1-8") 22-250 w/ heavy bullets (varget and H380 are good in the fast twist .223s as well. I don't know about the slower twist barrels though. I have never owned one).



I feel I have answered accurately since here a year ago I had this same question and called every powder, custom barrel, and bullet manufacturer I could (spent hours on the phone), and the above comments were the conclusion.

Just for the record---------------- double base powders burn at a lower temperature than single base powders. If you do not beleive this then contact Hodgdon powder via email and get the straight scoop.

TBS,

Hodgdon's is a dealer of powders nothing more, but them I seem to me paranoid about salesmen (you know the one about "you know when a salesman is lying, is lips are moving"). As far as temperatures go, I will trust the thermo-couples I have placed on barrels before I trust any salesman, regardless of who's powder he is peddling. I spoke in VERY general terms, and to my own data acquisition experience.

I little more about double base powders, again in VERY general terms, they tend to increase in pressure much more dramatically than do single base powders. In other words, the double base powders, again VERY generally, have more energy per unit mass than single base powders.

You are free to believe whom ever you chose. Frankly, I could care less.

ASS_CLOWN

I am not trying to correct you, but your comments seam to go against what both alliant and Hodgdons told me over the phone. CDH is accurate in what he says. Double base powders, thus ones containing nitroglycerine, have a HOTTER flame temperature (not cooler) in general and have the potential of burning out the barrel faster. Most all the companies I talked to stated this, and the rest say it won't make much difference, and EVERY one of them, including both Hodgdon and Alliant say to use the powder that outperforms the rest, whether it be double or single. (alliants reloader series are double base and Hodgdon's extreme line are single base as well as most of their rifle stuff). This subject has been brought up in other forums and the consensus is the same. Again, I wont stop using RL22 in my 270 and 300WM since I have some accurate loads with it, and it as well as many double base powders are excellent, but I still use H4831SC when it produces more accurate loads.

This is very interesting because I contacted Hodgdon several years ago about H380 and I was responded to by I believe Phil Hodgdon and he told me that H380 had a lower flame temperature but was harder to ignite than single base extruded.
Olin also claims a lower flame temp so I don't know what to believe.

I can also do a google search and find information stating the exact opposite, but they were talking about early manufacture ball powder.

Double base powders aren't all the same. The usual flake double base pistol and shotgun powders are very hot burning due to their nitroglycerine content in the 30-40% range. Ball powders seldom contain more than 10% NG, which doesn't make them a lot hotter. Then they have a high percentage of deterrent added, usually dibutyl phthalate, anywhere up to 7.5%. Dibutyl phthalate is a fuel with no free oxygen. It absorbs heat as it vaporizes, making a cooler and "richer" mixture in the powder gases. As a rule, Ball powders are the coolest burning. Somewhere around here I've got an old list of the (mostly) 600-800 series Olin Ball Powders' characteristics including their nominal flame temperatures. The coolest of the bunch was WC872, with 10% NG and 7.5% deterrent, burning at 2700K. (In their calorimetric bomb.) Most of those powders burned in the 2800-3000K range. 231 contained something like 30% NG and no deterrent, so its flame temp was a good bit higher. Can't recall exactly what it was, though. Wish I could readily lay hands on that paper; it got mislaid when my wife displaced my gun literature stuff out of a cabinet that got filled up with Beanie Babies!

Richochet, that would support what Hodgdon told me awhile ago. I am contacting them again to verify. Thank you for the info.

Another consideration is whether you hold pressure or velocity constant. Since ball powders create more velocity at the same pressure, you can load them to lower pressure to produce the same level of velocity.

If you load to a target velocity, it stands to reason that the lower pressure loads erode less, as well. IMO, that is why the armed forces use ball powder: lower pressure creates less wear all around. JMO, Dutch.

Dutch,

Where are you getting the

Quote:

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Since ball powders create more velocity at the same pressure

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from? In my experience, this simply is not true for the vast majority of ball powders. Typically, the slower ball powders run slightly lower pressures than the single base extruded powders, in their burn rate, but at significantly higher charge weights. What this means is that the SLOW ball powder run at a slightly lower pressure for a given velocity, which in reality is basically a mute point. The pressure differential; however, for these SLOW ball powders versus the equivalent single base extruded powder is typically less than 1%. For example a 55000 psi 30-06 load of single base extruded (say IMR4350)would equate out to a ~ 54455 psi load of an equivalent burn rate ball powder (say H414). Not too aweful significant really while both loads would have the SAME average muzzle velocity. You must understand that if you set the pressure equal you would not get a 1% increase in muzzle velocity, it would be more like 0.2% - 0.35% depending upon bore diameter. There are enough other variables in the rifle, bullet, powder, case, etc, system that generate greater variation that this.


Ricochet, excellent post!! I have found the faster ball powders to be very hot! As they are retarded they approach the single base powders and in some cases beating them too. It is nice to see a post with factual data in it for a change.

ASS_CLOWN

I got a response from Hodgdon powders this morning on this topic. This is the same response I got years ago so I don't understand why they told you the opposite.


quote:
Generally, ball type powders will burn at a slightly lower temperature
than single based powders. But, both burn at or near 3000 degrees K.
The slight difference in combustion temperature is not enough to make
much difference.

I also contacted Doug Shilen, who's barrels I use and his response was this:

quote:
Thomas-
Sorry . I never seen any difference in powders affecting barrel
ware. Pressure in itself , does shorten barrel life.


So I guess we can assume from the above statements it really doesn't matter whether you use ball or extruded and if you load to high pressure you will burn out your barrel prematurely.

I think your experience leads you to the wrong conclusion.

I don't have loading experience with the '06, and can't argue with your position other than to say that H414 is really a bit faster than 4350.

What I do know is that if you load RL22 and H4831 in say, a 270, the peak pressures at which you reach 2900 fps with a 150 gr. bullet will be considerably lower with RL22 than with H4831. The charge weight of RL22 will also be slightly lower.

In my experimentation with the 223WSSM and heavy bullets the same thing: Magnum and RL22 produce the target velocity at lower peak pressures than is possible with any single base in the appropriate range, including H4831 and 7828.

Ditto with my 7mag. Ditto with the Whelen (RL15 and Tac beat all), ditto with my PPC. FWIW, Dutch.

Dutch,



Rel 22 is an extruded double base powder.



Anyway, I find your comments very interesting. They do not seem to match my own, or those of several other reloaders I know.



For instance the 300 Winchester magnum with 26" barrel shooting

200 grain Sierra GK,

Remington cases.

Primers Fed 210

74 grains of H4831

Muzzle velocity 2869 fps



200 grain Sierra GK,

Remington cases.

Primers Fed 210

72.2 grains of IMR7828

Muzzle velocity 2887 fps



200 grain Sierra GK,

Remington cases.

Primers Fed 210

73.7 grains of Rel 22

Muzzle velocity 2871 fps



All three loads are accurate enough. Actually in my rifle the IMR7828 works best. These loads have been shot in three different rifles and believe me the velocities have not varied more than 10 - 15 fps between all three rifles (two M70 and one M700) all sporting 26" tubes.



The highest pressure, IMR7828, the lowest pressure H4831. At least that is what the strain gage said on the M700.



ASS_CLOWN

Well, I'm gonna throw my .02 in here. Throat erosion is primarily a funtion of PRESSURE, not flame temperature, velocity, or much of anything else. If it were velocity, the most severe wear would be at the muzzle. Steve is right about the flame temperatures being about the same, so kiss that theory goodbye too. It is a complex world in the barrel when a cartridge discharges, but it's not voodoo.

You will find, across the broad sweep of cartridges and guns, that virtually all that have reputations as barrel burners are high intensity(read: High Pressure) cartridges. When a cartridge fires, the pressure causes the chamber and throat to expand very slightly, and when it does this it causes very small fractures in the area of high pressure. You may correlate the pressure curve of a given round to barrel length and you will find that most of this damage occurs in the short distance of bullet travel where pressures exceed 50kpsi give or take. You may also accurately surmise that powder residue takes up residence in these small fractures, and corrosion results, regardless of your cleaning routine. The proof of this is found in a chamber/throat cast of a barrel so affected. I do not know that all barrels will suffer this but many will produce throat dimensions smaller in diameter than they were originally bored for, and this is a result of corrosion.

It is possible I suppose that getting a barrel very hot will exacerbate this problem, but it never seemed to slow my M16 down very much. Of course I wasn't too concerned about it back then either.

Okay, I got my asbestos suit on, fire away!

DigitalDan,

That may well be truth, and I know there is truth in some of what you are saying, if what you posted is the facts though, explain this.

Practically every single modern smokeless powder cartridge is loaded to 60,000 - 63,000 psi. So there really is NO such thing as a

Quote:

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barrel burners are high intensity(read: High Pressure) cartridges

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because ALL modern smokeless powder cartridges are "HIGH INTENSITY".

Or, am I missing something from your post?

ASS_CLOWN

I'll admit to a limited knowledge of internal ballistics but since we are on the topic, from a metalurgical perspective, what is going to cut metal is heat and pressure. This seems to point to rate of fire and velocity of gases in the barrel. The difference in heat generated by 5 shots/minute with a 300RUM is quite a bit higher than 5 shots/minute with a 30-06

Interesting question and everyone seems to have a theory. Unfortunately I'm not smart enough to say who is right or wrong but I will tell you what little I've learned and observed.



1. Somewhere around the time of World War 2, Chang Ki Chec ordered a bunch of machine gun ammo from the US. We were having to scrounge around to find enough various gun powders to fill the order. Naturally each lot and powder was tested. So the story goes, we noticed that the machinegun barrels testing the BALL powders considerably outlasted the STICK powders before accuracy went to hell. As a result the gun barrels were sliced apart to figure out why.



What they found was the STICK powders were eroding the THROAT of the barrels while the BALL powders tended to burn out the barrels further down towards the middle.



2. I think ALL gunpowders produce roughly the same TEMPERATURE as they burn. Somewhere around 4,500' if my memory isn't totally gone.



3. What we as reloaders mostly control is the PRESSURE, HEAT and AMOUNT of powder/bore diameter.



4. My hero P. O. Ackley hated overbore capacity cartridges with a passion. He may have been the first to coin the term "barrel eaters." And he correctly noted that OVERBORE cartridges uniformly have shorter barrel lives than. I think it's inescapable that there is a connection.



Take the .22/250s velocity of near 4,000 fps. Best barrel life should be somewhere around 2,000/2/500 rounds. Some fool ages ago went to the trouble to neck a 50 cal. bmg down to fire a .224 diameter bullet. Muzzle velocity was only a few hundred fps faster than the .22/250 but the barrel life was down in the double didgets.



This is an example of the fruits of overbore capacity in the extreme...but the lesson is there for all who care to read it.



So what's my conclusion? Like I said, I don't know. But my gut feeling is this. ALL powders are going to burn out barrels and IF all things are equal, they will do it at about the same rate...although where along the barrel may vary between stick and ball types.



What actually eats the barrel? I think it's a combination of HEAT/TURBULANCE/ABRASION.



I believe a steel melts considerably under 2,000'. Now if we are running gunpowder thru that barrel with a burn temp of over TWICE THIS...you see the problem.



If we pretend we are given a new machinegun and unlimited ammo to play with, we can stick in a belt, clamp down on the trigger and probably destroy the barrel in 500 rounds or less simply because we got the inside of that barrel so hot that a spitball going down it would scrape out some metal. OR, we could carefully regulate the firing of our new imaginary gun, never letting it get very hot, and it would last several 1,000 rounds.



This convinces me it's the heat/turbulance/abrasion etc that's destroying the barrel.......not the powder type...not the bullet velocity.



This is why cartridge efficiency is so important in any rifle you want good barrel life with. The more powder over the given bore diameter that you cram into the case to burn up in the next 26 inches of your barrel, the shorter that barrel will live.

There are other chemical factors related to the interaction of the hot gases and the steel as well. Hydrogen embrittlement. Formation of carbides and nitrides of iron. These compounds are hard and brittle, and they also melt at lower temperatures than iron. (That's especially important in erosion in artillery barrels, where the exposure time to hot gases is rather longer than in small arms.)



Powder gases are similar, but not identical in composition between different types of powder. And "they all burn at roughly the same temperature" is only true if you regard a range of about 400 degrees Kelvin as about the same.



Another thing that's very important is the dwell time at or near peak temperature. A small charge of a fast burning powder may have a very high peak temperature and pressure, but it falls off rapidly as the bullet moves down the bore and the gas expands. The steel near the throat is exposed to intense heating, but only briefly. A full capacity, compressed charge of very slow burning powder may reach the same peak pressure and temperature, but sustains it longer. That means more heat's transferred to the steel bore surface. It'll also produce a higher muzzle velocity. This is the reason for the mistaken conclusion that high velocities produce bore erosion. As has been correctly pointed out, the high velocities occur near the muzzle, while erosion's most severe near the chamber.

Higher pressure burns barrels faster for a given rate of fire. All of this becomes really simple when you view it that way.

RobertD

I shoot a lot of 223 and 22/250.

to me the simple formula is the less powder used the less throat erosion I am going to see.

the less barrel heat, the longer I can shoot and the longer it will take to wear out the barrel.

the less velocity, the longer the barrel life will be.
they always preach that concept on a 220 Swift.

I saw an interesting article on barrel life once that drew on some of ackley's experiments and some of the authors research. I apologize not remembering the article or the author, so bear with me. They compared a lot of rifles.

The barrel life of a 22 Long Rifle was listed as in excess of 50,000 plus rounds. The barrel life of a 30/30 was listed in excess of 20,000 rounds, 2100 fps.

Another article I remembered listed the velocity of a 22 caliber center fire with an MV of 2600 fps vs 3400 fps, as having 3 to 4 times the barrel life. It was speaking of 223's. ON a 22/250 it listed that the barrel life on one with a MV of 3800 to 3900, vs one in the 3000 fps range would increase the barrel life at the lower MV by threefold once again.

Finally an old local gunsmith of notarity that worked under Parker Ackley, told it to me another way, when asked about the life span of a barrel.

In " old timer" wisdom, his answer was 8 pounds of powder for a fast cartridge, 16 pounds of powder for a slow cartridge, until good accuracy starts to decline. Minute of Deer or Elk, he said just double those numbers.

When one starts to add up the amount of rounds one gets from a pound of your favorite powder, vs how many rounds it takes for throat erosion to show up, he was not far off of base.

Just passing on some "old timer'" wisdom, but I think it was a very accurate answer in real world terms.

so I make my 22.250 loads as 25 grains of IMR 4198 with a 52 grain HP as standard for prairie dogs ( MV of 3400), and 14.5 grains with a 46 grain HP Winchester bullet for an MV of 3250 fps/.

Cheers and good shooting
seafire

Richochet - I think you make a good point with your comment:

Quote:

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High velocities occur near the muzzle, while erosion's most severe near the chamber.

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Obviously the speed of the bullet doesn't have anything to do with barrel erosion. It's the fire behind the bullet that we need to watch.

AC, the Kings English is slippery sometimes, so I'm not sure what you call modern. A whole bunch of cartridges operate below that threshold. 30-30, 30-40, should I continue? There are anomalies within families of cartridges, such as the .270 Win. which is spec'd. higher by SAAMI than the 30-06. I cannot say that there is a linear relation to pressure and throat erosion but suspect it to be something of that nature. .22 rf's and other lead shooting production cartridges are relatively immune to this, while the other extreme as represented by the likes of the 7STW suffer greatly. I have read of wildcats with very small calibers and very large cases that have erroded bores beyond use before a working load could be developed. You can load catrtridges below SAAMI Spec pressures, and this increases barrel life quite a bit. You can start treading on 65kpsi or a little more and regardless of caliber or powder, barrel life will be fairly short.

I'm not familiar with the story that Pecos related and I don't know when help for machine guns came to the fore, but it is my understanding that by the time of Viet Nam that most if not all machine guns had Stellite inserts in the Chamber/throat region to deal with this. The alloy has some cobalt and nickel magic as I recall. I do not know how this relates to the issue here, but I don't think the M16 had such treatment. After a year in country(Nam) and firing more ammo than I can account for, it still shot adequately for my purposes. The rifling was getting a bit thin, or perhaps the copper was getting thick, I don't know. I may be wrong about this but I believe that the mil spec for the ammo in use at the time was 48kpsi.

Ball powders burns a little cooler than stick because of the heavy retardant coatings on most of them. They still release about the same energy by weight, and the temp. difference is minor. Their biggest advantage is metering.

My mind is empty now. For a good time, read the April 2003 edition of The Varmint Hunter, "What Happens To A Barrel", M.L. McPherson.

Yes TBS, I agree. I should have clarified what I said and Ricochet explained in more detail. The double base powders I was concerned about were double base extruded from alliant like RL22 which do burn hotter, but how much I don't know and I wouldn't worry about it. Fine tuned a load for my 270 using RL22 and I won't use another powder.

DD

Interesting logic, but it breaks down in one critical area. Consider this theoretical exercise:

If I load a .223 and a 220 Swift to the same pressure, fire them one round a hour for 10000 hours, which is going to wear out a barrel more? Never mind SAMMI limits, both cartridges are frequently loaded to similar pressures.

Or for case study #2, a .308 vs. a 300Win.....

I agree with another statement from several sources (like the trusty Sierra manual) that barrel life is best measured in lbs of powder. If you factor in bore size (smaller wears faster) and barrel heating (hotter wears more) you should have more than enough information to compare in VERY relative terms different calibers and loads.

Think about the process and compare it to a cutting torch. Hot gases impinging on metal heat and erode it. More gases (more powder) means more wear. Hotter and softer metal means more wear.

CDH, what is your point regarding the loading of two different cartridges to the same pressure level? That the one burning the most powder will wear faster? Is your trusty Sierra manual just talking about smokeless powder? Or should I start getting worried about the Sharps in 45-120-3 1/4?

Ricochet's post had some good info in the first paragraph of his post regarding chemical processes relating to the matter.

In the FWIW dept., this isn't my theory, or logic. Ablation does occur, so too does abrasion, but the wear associated with these factors is so small as to be inconsequential.

A not-so-rhetorical question for you: When the pressure in your .300 Whiz-Bang reaches 60kpsi, what is the pressure on the bullet base? More, Less, Equal?

I never give any thought to barrel life even on a .220 Swift imp. I'll shoot what works best, when accuracy goes to hell, we'll screw on another barrel there are people all over the world making them. Typically on the real hot cartrides ( .220 Swift, etc) that's about 3500 rounds if you use common sense and don't get the barrel too hot.