Powder coated vs lubed cast bullets and throat/bbl erosion

shuz

Active Member
Has anybody done, or know of any testing done to see how powder coating affects throat/bbl erosion vs regular lubed cast bullets.?
 

shuz

Active Member
Erosion or perhaps more aptly called "wear"does happen from hard bullets going thru the bbl, right? Since powder coated boolits in my experience are "harder than the hubs of hell ", I would think that shooting them would cause more wear on a bbl than softer cast bullets.
 

popper

Well-Known Member
Nope. High heat and high pressure gas, causes micro cracks in the steel which eventually chip off. Kinda like a plasma welder! Bullet may move a 1/4" but gas escapes at super sonic rate. Look at the base of a lead bullet shot with stick powder and see the indentations from HV impingement. Land wear - no worse than jacketed.
 

glassparman

"OK, OK, I'm going as fast as I don't want to go!"
I'm no expert but I would think it would take a whole lot of shooting to get to a measurable difference if there is one?

If I look at how long it takes to "shoot out" a barrel using regular jacketed, I would think cast even if hard would be more than double to get to the same point. Not sure I would ever shoot that much from one weapon to actually have measurable wear.

Or am I on the wrong track?

Looking to learn here as well . . .

Mike
 

Rockydoc

Well-Known Member
The 264 Winchester Magnum is reputed to shoot out a barrel in short order with hot loads. The 260 Remington shooting the same exact bullet would take thousands of rounds, if ever, to shoot out a barrel. The difference: lots more powder burning in the throat of the barrel each shot. The bullet is not what wears the barrel out, it is the gasses.
 

Snakeoil

Well-Known Member
I think a common misinterpretation is that a "shot out" barrel is worn for its entire length. But they are normally just erroded from the end of the chamber to a few inches beyond the chamber. Long range shooters have been known to use a 32 inch barrel for their initial build and when the accuracy starts to diminish, they whack off 6 inches, rethread, and rechamber the barrel and are back in business. This makes sense when you consider some of the really hot longrange calibers will kill a barrel in 1500 rounds. Even a .308 will start to see accuracy diminish around 3500-4000 rounds. That's a lifetime for most folks. But for serious shooters, where you make shoot 100 or more rounds/match, that life will be reached in relatively short order.
 

Bret4207

Northern NY Dangerous extremist...???
Erosion or perhaps more aptly called "wear"does happen from hard bullets going thru the bbl, right? Since powder coated boolits in my experience are "harder than the hubs of hell ", I would think that shooting them would cause more wear on a bbl than softer cast bullets.
Are you talking the bullet or the coating that's hard?
 

CWLONGSHOT

Well-Known Member
Excessive & rapid erosion is the product of HEAT/PRESSURE. Two things NOT regularly associated with cast bullet shooting.

Not sure why the hang up some folks have with powder coat... ITS PAINT! Its harder then many alloys but MUCH softer then copper/brass thats common with a jacketed bullet besides the afore mentioned lower pressures.

ORIGINAL lead shooters (Blk Powder firearms) also do not have or more accurately where not made with steels as durable/hard as typical rifles today. So shooting cast thru these is even MORE DUREABLE/RESISTANT to any kind of wear associated to cast bullets of any form.

CW
 

Ian

Notorious member
Heat/pressure checks the throat surface and physical abrasion of burning powder kernels/primer dust blowing through there blasts off the checked/fried surface, rinse and repeat.

If anything, PC'd bullets reduce any bullet-induced erosion to nil, in fact PC'd cast won't even wear the burr off of a gas port hole in 500 rounds.
 

RBHarter

West Central AR
I believe it was Townson that did the between wars study with some 10 03's to determine barrel accuracy life . The results were that the life was 30 seconds . At .007 seconds being the time between primer ignition and clearing the muzzle as barrel time it comes out at 10,000 rounds . The between wars early 06' was probably loaded with something less abusive than Cordite and faster than 4350 probably something akin to BL-C produced by DuPont no doubt maybe summer and winter ammo ..... In any case it was just standard issue FMJ ball probably surplus from the 1918 to 1919 production in about 1934/5 as I recall , it's been a long time and when wasn't as important as the context and outcome. We have in theory better suited steels , infinite powder choices , and really we should be getting longer barrel life not less . We have introduced powders that "scrub copper fouling" as they go , (in my best gump)"I ain't a smart man but" as a mechanic if it removes bearing transfer as it's laying down more it's going to decrease the net life expectancy . You just can't strip away something while you add to it . Applying a layer of antistick slickum' sure I'll buy that but I didn't see any difference in performance in several dry films that I tried , including a snake oil trial I tried over there most of 15 yr ago , dry film graphite, Teflon (which made a gooey mess and sucked in the cold as shotgun action slickum') and a couple.of.other wonder slide deals .

Old school 50kpsi 30 cal FMJ at 2/3 case dia to bore dia reaching maximum acceleration at 23" of barrel has a 10k round life for a GI barrel to hold 3 MOA .

Larger case to bore rates have faster wear . The kings of that example are the 220 Swift and 264 WM which is weird because something magical must happen in that .02 span between .264 and .284 because the 7mm RM has beat that wrap . The 22-250 is supposed to be hard on barrels but nothing like the Swift ....... The shoulder angle of the 22-250 maybe ? I mean if there were ever commercial brother of another mother's on the shelf those 2 are it . The 22-250 did have the advantage of more modern powders so maybe that's part of it , maybe a big part of it . I'd say that's probably the difference between the 264 and 7mm too .

Using the idea and scale the 25-06' should be a destroyer of barrels too but it was loaded with magnum type powders from the outset , and came in just in time for a war then got held up another 15-20 years and it had even better powders thanks to a million pounds of surplus H4831 left over from 20 mm cannon production .

Any time we load for zero deviation, maximum velocity, applications it's going to be hard on equipment.

When one leans on numbers to look for answers because that's a real standardized base to stand on BC is the only difference between nominal loadings by bullet weight between the 7RM and 06' . I don't know how life is with the 280 but with a little "headspace manipulation" the AI can get back the 100 fps it loses to the bore dia and the 06' . It's harder on barrels maybe than the RM which is weird because they are probably closer dimensionally than the 220 and 22-250 and share the shoulder but not the neck .

Just the mechanics point of view again but we are again entering a why some do and some don't situation that is driven by powder column length and the top 1/2" of the cases shape . Which sounds like an echo of something I read someplace now that I've written it down ....... Round , square , length , angle , taper , all applied to body , shoulder , and neck . It may have been during the Lazeroni push that I was reading about it all , years before the Short Mag run .

It can be bantered all day and night but until we have the means to look at the actual events that are occuring during .0095 seconds in something north of 100,000 fps maybe as high as 500k frames we can only tap the numbers and impact results.
 

Ian

Notorious member
Ha! I remember the PB-Blocker debacle, what a farce. Been so long I forgot who else tested it.
 

RicinYakima

High Steppes of Eastern Washington
The other part of the Frankfort Arsenal report was the time factor. Shots fired a one per two minutes resulted in 20,000 rounds. Shots fired in rapid fire, 10 shots in one minute, resulted in 5,000 rounds. One of the results of this study was the development of DuPont IMR (improved military rifle) powders.
 

Bret4207

Northern NY Dangerous extremist...???
Okay, but the ductile, "soft" bullet is underneath and the coating will give with the bullet as it enters the leade. It's not like it's steel on steel. I would be concerned if the coating had a Bhn of 50 or something, but I've never heard that it does, maybe one of the PC boys here can offer some info. I was also concerned the powder coat might be abrasive, but I've seen no reports of that either. The paper used in paper patching has some abrasive quality, some types at least, but users report a polishing action. I have no experience with PCing at all, but considering that even with copper clad jacketed bullets we know it's the hot loads that cause the problems...I'm not sure it's a giant issue.
 

Bret4207

Northern NY Dangerous extremist...???
I believe it was Townson that did the between wars study with some 10 03's to determine barrel accuracy life . The results were that the life was 30 seconds . At .007 seconds being the time between primer ignition and clearing the muzzle as barrel time it comes out at 10,000 rounds . The between wars early 06' was probably loaded with something less abusive than Cordite and faster than 4350 probably something akin to BL-C produced by DuPont no doubt maybe summer and winter ammo ..... In any case it was just standard issue FMJ ball probably surplus from the 1918 to 1919 production in about 1934/5 as I recall , it's been a long time and when wasn't as important as the context and outcome. We have in theory better suited steels , infinite powder choices , and really we should be getting longer barrel life not less . We have introduced powders that "scrub copper fouling" as they go , (in my best gump)"I ain't a smart man but" as a mechanic if it removes bearing transfer as it's laying down more it's going to decrease the net life expectancy . You just can't strip away something while you add to it . Applying a layer of antistick slickum' sure I'll buy that but I didn't see any difference in performance in several dry films that I tried , including a snake oil trial I tried over there most of 15 yr ago , dry film graphite, Teflon (which made a gooey mess and sucked in the cold as shotgun action slickum') and a couple.of.other wonder slide deals .

Old school 50kpsi 30 cal FMJ at 2/3 case dia to bore dia reaching maximum acceleration at 23" of barrel has a 10k round life for a GI barrel to hold 3 MOA .

Larger case to bore rates have faster wear . The kings of that example are the 220 Swift and 264 WM which is weird because something magical must happen in that .02 span between .264 and .284 because the 7mm RM has beat that wrap . The 22-250 is supposed to be hard on barrels but nothing like the Swift ....... The shoulder angle of the 22-250 maybe ? I mean if there were ever commercial brother of another mother's on the shelf those 2 are it . The 22-250 did have the advantage of more modern powders so maybe that's part of it , maybe a big part of it . I'd say that's probably the difference between the 264 and 7mm too .

Using the idea and scale the 25-06' should be a destroyer of barrels too but it was loaded with magnum type powders from the outset , and came in just in time for a war then got held up another 15-20 years and it had even better powders thanks to a million pounds of surplus H4831 left over from 20 mm cannon production .

Any time we load for zero deviation, maximum velocity, applications it's going to be hard on equipment.

When one leans on numbers to look for answers because that's a real standardized base to stand on BC is the only difference between nominal loadings by bullet weight between the 7RM and 06' . I don't know how life is with the 280 but with a little "headspace manipulation" the AI can get back the 100 fps it loses to the bore dia and the 06' . It's harder on barrels maybe than the RM which is weird because they are probably closer dimensionally than the 220 and 22-250 and share the shoulder but not the neck .

Just the mechanics point of view again but we are again entering a why some do and some don't situation that is driven by powder column length and the top 1/2" of the cases shape . Which sounds like an echo of something I read someplace now that I've written it down ....... Round , square , length , angle , taper , all applied to body , shoulder , and neck . It may have been during the Lazeroni push that I was reading about it all , years before the Short Mag run .

It can be bantered all day and night but until we have the means to look at the actual events that are occuring during .0095 seconds in something north of 100,000 fps maybe as high as 500k frames we can only tap the numbers and impact results.
On the Swift- IMO the barrel burning was at least partially due to people taking heavy rimfire barrels and trying to use them as Swift barrels back in the early days. And many barrels back then were a lot softer than what we use today. Shoulder angle, powders, etc. also probably had a lot to do with it. I have a 6.5-06 barrel that started life as a Swift barrel back in the late 40's and used by a dedicated chuck hunter. He "shot out" the Swift barrel and then "shot out" the 6.5 barrel. I'm betting it was the relatively soft steel and hot loads doing the dirty deed.

On the 264WM vs 7 Mag, maybe the 7 Mag doesn't get the barrel burner rep because it tends to be loaded with heavier bullets and kicks a lot more so people don't go out and shoot them all that much?
 

Snakeoil

Well-Known Member
Don't forget, we are talking about the gun world here. The urban legends, misunderstood comments rephrased and passed on as fact, as well as total BS uttered by some old guy, tend to get passed along and take on a life of their own. Anyone who has gotten deeply immersed in one particular shooting sport will tell you how much BS they had to sift thru before they had a good and factual understanding of what they needed to know in order to do well, achieve a particular goal or make an informed choice. I had to admit there was a time when I thought barrel erosion was wear for the full length of the barrel from the bullet slowly wearing it away. And there may be some truth to that from the days of powders that left a lot of carbon behind and barrels that were made from milder steel. But today, with modern steels it is a high velocity hot gas doing the damage. It is similar to what you see on the top strap of a revolver that shoots hot pistol loads its entire life.

Even the experts back in the day were formulating opinions or theories based upon what they knew. But as we all know, you don't know what you don't know and missing a key point can take you down the wrong path. Remember moly-coated bullets?

Like everything else, I tend to believe that some of the breakthroughs in understanding what is going on from the time you pull the trigger to the time the bullet strikes the target were pure luck. Somebody tried something almost as a whim and it worked. Or better yet, they made a mistake and that proved to be beneficial. They got credit for the idea and suddenly they are revered as an expert when in fact all that happened was, they got lucky. That's the story of Gortex. It was a process mistake that created the stuff. Damn good mistake once they saw the value in the new product.
 

shuz

Active Member
OKAY yinz have convinced me that my concerns about powder coating damaging my bbl should be no more than shooting normal cast boolits at normal (1500-1700fps) velocities.
The reason I asked the question is that I am getting some fine, small, less than 1" groups with powder coated bullets and was concerned about their possible damage to my bbl.
Thanks for all the answers !