Slower powder easier on barrel?

[DLCTEX]

Am I correct in thinking that the slower powders are easier on barrels? I am using 7828ssc in my 257 wby. mag. and am thinking that with condom bullets the barrel life will be longer. What does the board think? I plan to shoot cast in it most of the time to extend barrel life to the fullest, if I can work up a load that will work for me. Dale

[felix]

That is a loaded question, Dale. The answer is based upon how much heat is generated, when and where. Really cannot answer that question without some doubt. For example: hot enough for sandblasting the throat area, versus cool enough for the throat, but heat delayed far enough to cause burn a little further from the throat, making the whole area more uniform in destruction and less overall. Pick your poison. The one to pick would be using the current seating arrangement. If there is enough boolit in the case, you can seat further out as the barrel wears. This would indicate the preference is for the throat burn over the delayed burn. ... felix

[405]

I kinda like Felix' reply.... almost political

WAG about the over bore types (257 Wby, 264 Win, etc.) is that fast powders are not used in them except for very light or cast loads so by design and default the fast powders would be easier on the bore.

WAG about the opposite extreme within the straight-walled case category where usually higher charges of a slower powder are used to obtain higher MVs which translates into higher gas velocities thus more erosion. Peak chamber pressures may not have a direct and linear affect on bore erosion. Something like "time" or "quantity" of pressure might have a more direct affect and cause more erosion. This would apply to comparing the faster to the slower powders where the slower powders are contained adequately by the inertia of the bullet and have reached progressive burn thus more "time and quantity" of pressure thus more gas at high velocity thus more erosion.

The extremely slow powders in short, straight walled cases and/or short barrels where they don't get up to working pressure would be along the lines of Felix' post. In those instances much of the energy of the powder is expended outside the muzzle so the example would be "loaded" and the slower powders would be easier on the bore.

Both are just WAGs, at best SWAGs

[felix]

Yeah, velocity won't destroy a barrel on its own accord. It is the generated heat from the powder burn that burns the steel. After the steel is burnt real good, projectiles then pick up the platelets, particles, etc., and take them on out. Latency of the steel type to accept enough heat for damage is a major criteria. Barrels with a bigger diameter will act as a bigger heat sink and will last much, much longer. ... felix

[Bass Ackward]

It's heat energy under pressure. Now I suppose that an argument can be made for the length of time for that heat, (slower powder) but the biggest factor is case capacity which means more focused energy in a smaller bore. What happens when you focus a cutting torch?

The good news is that your barrel will last longer than you expect. Bad news is that your throat won't. But accuracy will be eventually lost by the gas escaping at the muzzle which is what really ruins accuracy. Or over cleaning.

You got a limited life gun just like the rest of us. Enjoy it for what it is, for as long as it lasts. Then plan your next step.

[runfiverun]

i yhink that with the slower powders trying to burn down the bbl
you also have unburned powder scouring the bbl also.
kind of the cow thing going on here
just my theory on overbore.

[mroliver77]

Good news Dale! Prices will be so high you will not be able to afford to toast your barrel. ;( A friend lopped the chamber end off a hot rod .22 barrel and split it down the middle to get a good look at it. I was surprised to see burnt steel that looked as though tiny pieces had been flaking away.
J

[bobk]

I've been thinking about this. One work-around in my Father's .270 was to use Nosler Partitions, The sorta open base seem to shoot more accurately. Now, this MAY have had nothing to do with the open base. It may have been because of the length of the full diameter portion of the bullet, or boolit, depending upon what you are using. I have found that the length of the throat of the rifle should be no longer than that full diameter portion. In my mind, what is happening is that the bullet enters the rifling while the base is still supported by the case neck. For the life of me I can't understand why the throat immediately ahead of the neck on a .300 Win is spec'ed at .315! Maybe this is why it really likes heavier bullets. Same with my .257 Roberts. It's an old, long-throated M77 Ruger, and won't shoot anything under 100 grs. Those, it shoots brilliantly!

The other thing I've been wondering about is how neck length affects erosion. The first Sharps brass cartridges were bottlenecks, but later they went to longer straight cases, to reduce the fouling right ahead of the chamber. I wonder if a similar dynamic is affecting throat erosion? I'm imagining that the expanding powder gasses + unburned powder are exiting the case in a swirling motion, and blowing into the steel ahead of the chamber. This blows carbon into the steel, as I understand it, which hardens the steel to the point of brittleness, and it subsequently chips off. The more "overbore" the cartridge, the more pronounced this effect, due to the lower expansion ratio, so it is pressure duration related. Another question just came to me: Does blowing carbon into the lead bullet base make it more brittle? If so, the effect should be most noticeable right at the edge of the base of the boolit, causing pieces of detached lead to TRAIL the boolit, and solder fast to the bore from heat, rather than the standard explanation of melting off and blowing up alongside an undersized but not obturated bullet. In other words, does the lead melt off, break off, or some of both?
Bob K

[runfiverun]

you might get a" plug" of powder following the bullet also if you have those tapered
shoulders.

i think the reason that they went away from those cases in the sharps is that
any kind of shoulder in bp cartridges raises pressures unecessarily, if they are tapered
or gradually tapered or straight you can get more powder and vel, with out the pressures.

[brshooter]

If you ever get a chance to use a borescope, check your barrels and throats of them. The real worn out ones are spectacular. The bore in front of the chamber looks like alligator hide. the metal is cracked and the cracks are lined with copper. Carbon build-up is a real barrel killer. I cleaned for copper build-up in my BR rifles thinking I was getting the carbon too. Was I mistaken, had both guns rebarrelled by a real gunsmith. When I went to pick them up, he showed me what to look for as far as carbon was concerned. He shortened the two barrels I had on the guns and rechambered them. The stubs he saved to show me and to compare with the six barrels I had him do. he used Deltronic Pins to measure in front of the chambers and also measure the new barrels. On both used barrels in front of the chamber, carbon had restricted the bore by more than 0.002". The rechambered barrels shot great, in fact I came in 12th. at the Super Shoot that year.
I guess what I'm saying, no matter what you shoot, clean that barrel properly and as soon as you finish shooting to keep it shooting well. A borescope is a great help, and is the only way to see if you are cleaning properly.

[felix]

Great show, my man! I never had the fortitude to go to the SuperShoot. It was the lack of confidence on my part in reading conditions good enough to think I could have completed a competitive group, much less an aggregate. Chicken schitt, you bet! Yeah, that carbon build up will do a number, but with boolits the problem becomes more of a catch-22. Carbon is a great insulator, and most especially when lube is mixed with it. However, if that lube gets hard, and it will sooner than one would think, as the carbon converts the lube to concrete. So, those tornado brushes are resorted to. Not recommended to use these things unless they are new and have no sharp edges. The sharp edges will take up the platelets, if any, below the carbon. Need the bore scope to find out for sure, but I would bet on it. ... felix

[charger 1]

Am I correct in thinking that the slower powders are easier on barrels? I am using 7828ssc in my 257 wby. mag. and am thinking that with condom bullets the barrel life will be longer. What does the board think? I plan to shoot cast in it most of the time to extend barrel life to the fullest, if I can work up a load that will work for me. Dale

As a general rule of thumb spherical vs extruded is more what decides throat wear. Extruded powders being worse by quite a margin than spherical

[lovedogs]

I agree with all that's been mentioned and would add a little more. Where I live many shoot out their bbls. in prairie dog towns. Besides all the things mentioned I feel that rate of fire and cleaning of a bbl. have a real pronounced effect. We all know heat is one of the enemies. That relates to rate of fire. Heat generated by one powder over the other, in my opinion, is secondary to rate of fire heat. Consider a cutting torch. When steel gets to a certain temp it erodes away readily. The other culprits are a little harder to define. Carbon and copper fouling are hard to address. For years we didn't have effective solvents to deal with these. Nowadays we have no excuse for heavily fouled bbls. I can't count the number of old copper-filled bbls. I've resurrected for friends who thought they'd "shot out" their bbls. My policy now is to not shoot a bbl. too hot and keep it clean. In several of my .22 centerfires and at least one .25-06 I've shot more rounds through them than is supposed to be possible and so far I can see no erosion or accuracy deterioration. In fact, some of them are getting wonderfully smooth and easy to clean as well as shooting better than most will believe.

[felix]

True. A barrel which is too hot to hold for more than a second may not be too hot internally to cause the barrel to begin the self destruct stage. It is the RATE of internal fire without doubt. Gosh, the sun down here makes the barrel (4140 or some such) too hot to hold even without firing one shot! ... felix

[DLCTEX]

I cleaned the barrel on the Weatherby after the first 20 shots. Sprayed it with brake cleaner and took a look, it looked chrome plated, really impressive. I ran some Hoppes patches,4, and then Outer's Foul Out, not a trace of blue. Does Weatherby lap the bores? This is the smoothest new bore I've ever seen. DALE

[PatMarlin]

I guess what I'm saying, no matter what you shoot, clean that barrel properly and as soon as you finish shooting to keep it shooting well. A borescope is a great help, and is the only way to see if you are cleaning properly.

Oh boy there goes the "Never clean a good shooting Cast Boolit bore" theory ala Veral Smith and others.

[charger 1]

Oh boy there goes the "Never clean a good shooting Cast Boolit bore" theory ala Veral Smith and others.

I'd be one of thse "Others" . If a fella wouldnt clean a 22 RF barrel then why a cast barrel?

[PatMarlin]

We been knowin' you were one of those "others" Chargar..

Jus kiddin'..


There are no absolutes in this field. I guess that's what keep us going otherwise we would be bored and move on.

[charger 1]

Well I've been noticing. Not everybody is right about all things, but if you have the common sense to set out and take the very best of everybody you can end up with very fine duplicatable resuslts. Did any you guys ever play with that puter program from a few yrs back" build the perfect woman"? Well do that, except you dont get to pick the best boobs, butts, etc. You pick the best knowledge. Lets be honest Nobodies right about every single thing, yes even my Veral man. BUT if you take the best of Verals ideas on hardness, rotation, conditioning bore, add them to the best of Dan from mountains ideas on throat fit, etc etc etc. You can (AND I HAVE) build a formula for creating an accurate boolit to gun match perdy darn close to 100% of the time... My thoughts anyhoo

[lovedogs]

charger 1... like I've always said when it comes to listening to advice, "take the best and leave the rest." Dale... I wouldn't be surprised if some bbls. look like chrome because some manufacturers do chrome plate their bores. The Brownings and Winchesters in the new short magnums are chromed. It wouldn't be any surprise to learn that Weatherby is doing that with some of their hot numbers.