Load limits question...

[AJC1]

When loading lead you should never be able to get a pressure limit faster than an equivalent jacketed load based on material properties and bearing surface of a jacketed bullet vs the driving bands on lead bullets. If this is not true the explain why...... load limits in most cases are a factor of leading or the bullet slipping the rifling. So if you find a load for a jacketed bullet than a reduction of 10% gives you a working range to test.

 

[GeoDudeFlorida]

When loading lead you should never be able to get a pressure limit faster than an equivalent jacketed load based on material properties and bearing surface of a jacketed bullet vs the driving bands on lead bullets. If this is not true the explain why...... load limits in most cases are a factor of leading or the bullet slipping the rifling. So if you find a load for a jacketed bullet than a reduction of 10% gives you a working range to test.

Mostly true.

While Linotype is not as hard as copper jacket, it is hard enough not to skate rifling even if driven at jacketed speeds IF two conditions are met: it has to be sized to fill the bore; and, it has to be lubed to seal completely. A gas check on Linotype or #2 Alloy lead helps meet those conditions: seal the bore and prevent leading; but! a proper lube to seal fore and aft of the driving band is still required. Hard lubes like Carnauba Blue/Red/White were invented specifically for that kind of application: a very hard, almost brittle bullet, pushed at jacketed velocities. The wax coats the bore and helps seal.

 

[edwardware]

When loading lead you should never be able to get a pressure limit faster than an equivalent jacketed load. . .

This is a confusing choice of words.

I speculate that you meant, "When loading lead you should never be able to get a higher pressure that the same charge under a jacketed bullet of the same weight."

If that's what you meant. . . not exactly. In theory a jacketed bullet could have such short bore contact that the reduced friction inverted the usual rule. Bore fouling can also invert this (see Glock's faux-rifling).

But, in general (almost always), a lead bullet will develop lower bore friction than a jacketed bullet.

Also in general, in cartridges designed for jacketed bullets, most weights of lead bullets will be limited in useful velocity by slipping across the rifling, not peak pressure. This is often not the case with heavy-for-caliber bullets, or small volume cases.

ETA: and I see @GeoDudeFlorida brought up harder-than-lead lead bullets. . . that too!

 

[reddog81]

Lead bullets are usually sized larger than similar jacketed bullets. I've read that the initial push into the rifling can cause higher pressures with lead due to the larger diameter bullet. This is occurring while the bullet is still in the case and pressures are at their highest. Once the bullet is fully in the rifling the lead will move easier, but by then the pressure the pressure has already dropped from peak levels.

I have no evidence of this. Just something to consider....

 

[GeoDudeFlorida]

This is a confusing choice of words.

I speculate that you meant, "When loading lead you should never be able to get a higher pressure that the same charge under a jacketed bullet."

If that's what you meant. . . not exactly. In theory a jacketed bullet could have such short bore contact that the reduced friction inverted the usual rule. Bore fouling can also invert this (see Glock's faux-rifling).

But, in general (almost always), a lead bullet will develop lower bore friction than a jacketed bullet.

Also in general, in cartridges designed for jacketed bullets, most weights of lead bullets will be limited in useful velocity by slipping across the rifling, not peak pressure. This is often not the case with heavy-for-caliber bullets, or small volume cases.

ETA: and I see @GeoDudeFlorida brought up harder-than-lead lead bullets. . . that too!

Yup.

It also depends on the duration and direction of the pressure source, and to a lesser degree (pun intended) the heat generated by that source: from within the case or throughout the barrel length?
That's why we agonize so much over powder choice. Ed Harris and his cohorts did a lot of writing about this topic and came up with some interesting theories, some proven and some not, about how time, pressure, and friction interact to create ideal load combinations. Consider a .30-06 and Harris' "The Load":
You want to stay under 50kpsi for safety and so you can use the same loads in older rifles; your pressure range for accuracy and safety is 15-50kpsi.
Ed Harris' "The Load" is 13gr of Red Dot w/ a 150gr. LFN-GC hard-wax lubed bullet made of 5-5-90 #2 Alloy at 18-20 BHN and 45kpsi - you get 1500fps at the muzzle. By the time the bullet exits, it is decelerating.
18grs of 2400 is 35kpsi but you get 1850 fps from the same bullet.
30grs of 4895 is also at 35kpsi and you still get 1850fps but the bullet's velocity is constant as it leaves the bore.
45grs of 4831 is about 45kpsi but you get close to 2400 fps and a longer barrel would yield higher velocity (probably but just barely) because the bullet is still accelerating under pressure as it leaves the bore.
A softer alloy *can* work better as your velocity increases even if the pressure stays in the same range as it takes longer driving the bullet down the bore with less heat friction and a longer acceleration curve, allowing the "bite" on the lands to hold.

 

[Charlie98]

Yea, what they all said... ^^^

Much of what GeoDude elaborates on in #5 is why I usually pick fast rifle powders over slow pistol powders for cast in rifle. I have most of my rifles that shoot cast sorted out as far as bullet diameter and such, and I've explored QuickLoad a little to see where the pressures are on a few favorite loads (for validation.) What I don't like is the peak pressure of slow pistol powders... moving a heavier bullet into the lands and sticking, however momentarily, right there until the pressure overcomes the resistance... and then the bullet moving along. The same pressure spike is there, even with jacketed, but with rifle powders (vs slow pistol powders) the peak isn't so violent, or has less potential to be. At least that's how I understand it.

 

[AJC1]

Mostly true.

While Linotype is not as hard as copper jacket, it is hard enough not to skate rifling even if driven at jacketed speeds IF two conditions are met: it has to be sized to fill the bore; and, it has to be lubed to seal completely. A gas check on Linotype or #2 Alloy lead helps meet those conditions: seal the bore and prevent leading; but! a proper lube to seal fore and aft of the driving band is still required. Hard lubes like Carnauba Blue/Red/White were invented specifically for that kind of application: a very hard, almost brittle bullet, pushed at jacketed velocities. The wax coats the bore and helps seal.

Powder coat fixes most of these issues. The train of thought is how to safely explore the limits of my powder coated bullets. The limits in the manuals are not stated for just to understand and adjust accordingly. The only limit I can think of is bullet design affecting seating depth. A deeper seated bullet will always raise pressure and should not be casually moved past, without real consideration. Things like lube limits for traditional bullets and jacket shedding for platted are really not applicable. Understanding and applying the correct limits for safety is my goal and knowing the limitations is what I'm trying to figure out.

 

[GeoDudeFlorida]

Powder coat fixes most of these issues.

Well, now, not really. PC doesn't liquify. That's how hard wax forms a seal in the bore. PC doesn't protect the lead from skating either. Only hardness and a correct pressure curve can do that. A gas check might help with the seal but if a bullet's too soft for the pressure, or the way that pressure's applied, using too fast or too slow a powder, too small or too large a diameter, then you can still get bore skate, leading and bad accuracy. There's a reason people still use wax and grease lubes and it's not because they're stupid or stubborn. Powder coating isn't a hard jacket. All it does it protect the lead from burn-off when the hot gasses blow-by the skirt. You won't get leading at higher-than-bare lead velocities. That's nice but it's really only marginally related to how fast you can drive a lead core.

 

[AJC1]

Well, now, not really. PC doesn't liquify. That's how hard wax forms a seal in the bore. PC doesn't protect the lead from skating either. Only hardness and a correct pressure curve can do that. A gas check might help with the seal but if a bullet's too soft for the pressure, or the way that pressure's applied, using too fast or too slow a powder, too small or too large a diameter, then you can still get bore skate, leading and bad accuracy. There's a reason people still use wax and grease lubes and it's not because they're stupid or stubborn. Powder coating isn't a hard jacket. All it does it protect the lead from burn-off when the hot gasses blow-by the skirt. You won't get leading at higher-than-bare lead velocities. That's nice but it's really only marginally related to how fast you can drive a lead core.

True and that limit is one of the two I addressed in my OP. I'm not sure if this ideology tracks with rifle at all and while I continue testing in pistol I'm considering they may react very differently. 40k and 62k are far from the same. I did watch a video where fortunecookie45lc was using lube in 45-70 with PC bullets. His long barrel was exceeding the limits of PC. I learn a lot and enjoy the content of his videos.

 

[GeoDudeFlorida]

True and that limit is one of the two I addressed in my OP. I'm not sure if this ideology tracks with rifle at all and while I continue testing in pistol I'm considering they may react very differently. 40k and 62k are far from the same. I did watch a video where fortunecookie45lc was using lube in 45-70 with PC bullets. His long barrel was exceeding the limits of PC. I learn a lot and enjoy the content of his videos.

Ah. okay. To be clear, I was almost exclusively talking about rifle cartridges.

 

[AJC1]

Ah. okay. To be clear, I was almost exclusively talking about rifle cartridges.

That is relevant to the question because that's some of the knowledge I need. I only responded with the experience I have and admit freely that is limited. I push every time I'm out shooting or on the bench to learn as much as possible, while minimizing the danger. Zero injuries is my expected result. Leaded barrels or actions full of powder are just temporary inconveniences.

 

[forrest r]

When loading lead you should never be able to get a pressure limit faster than an equivalent jacketed load based on material properties and bearing surface of a jacketed bullet vs the driving bands on lead bullets. If this is not true the explain why...... load limits in most cases are a factor of leading or the bullet slipping the rifling. So if you find a load for a jacketed bullet than a reduction of 10% gives you a working range to test.

Actually I don't agree with any of the statements above.

A strait walled case is just that, strait (45-70) and shouldn't even be in this conversation. The guy ran out of pc coating because of his errors, the bullet design or the quality of the bbl or a combination of any of those errors.

Powders like "reddot" shouldn't be in these types of conversations. Nor should 2400 or 4227, ya big deal 2400 & 4227 were designed to be rifle powders. WWWWWWWWWWWWWWEEEEEEEEEEEELLLLLLLLLLL that was +/- 90 years ago, hopefully there has been a little progression since then.

Efficiency is the name of the game. A cast bullet is a lot more efficient then a jacketed bullet in bottle necked rifle cases. A cast bullets ability to seal the bbl before the full length of the bullet enters the bbl is superior to it's jacketed counterparts. This in itself increases the short start pressure and over all pressure of the same load. The powder will burn more efficiently creating higher pressures.

Ed Harris name keeps coming up for some odd reason. Don't get me wrong I flat out love what Harris has done for cast bullets in general. But his thinking was outdated when he was designing bullets. And now you can add +/- 20 years to his outdated thinking. Don't think so??? All's you have to do is look at his 7.63 x 39 designs. There's a traditional lube grooved design and a tumble lube design. Harris didn't understand lubes or the strength of the tumble lube bullet design. Hence 2 drastically different bullet designs when in reality all's anyone needs is the tumble lube design that is superior to it's traditional lubed grooved counterpart.

A lead bullet "slipping" as you put it is caused from the rotational torques exerted on it. Doesn't matter if it's a rifle, pistol or revolver. In a rifle or pistol the chamber has a ball throat. The front of the bullet starts rotating in the lands while the body/base of the bullet is expanding/locking/grabbing the ball throat while still being pushed strait forward. It's this rotational torque that's exerted on the bullet that causes the slipping/stripping/skidding.

While pc isn't a cure all it definitely doesn't have to "liquify" to seal the bbl. If a pc'd bullet doesn't seal the bbl it's because of either operator error or mechanical issues with the bbl. PC'd bullets are more forgiving and it's easier for them to outperform their traditionally lubed counterparts.

 

[243winxb]

https://www.thehighroad.org/index.php?media/albums/load-data-lead-vs-jacketed-bullets.265/

Lead vs jacketed.

I looked for factory data to compare, same weight bullets, with same powder. Pressure is listed.

Not all bullets weights are listed in the photos. Look for the ones that are.

 

[forrest r]

Ya but your looking at fast burning powders in small volume strait walled cases that are affected by the bullets length/seating depth/case volumes a heck of a lot more that a bottle necked 308w, 30-30 or 30-06 for example.

Apples vs oranges

 

[Charlie98]

Powders like "reddot" shouldn't be in these types of conversations. Nor should 2400 or 4227, ya big deal 2400 & 4227 were designed to be rifle powders.

As previously noted... that's kind of my thinking. I've fooled with pistol powders in rifle cartridges, sure, and they work... but IMHO, not as well as a true rifle powder. Am I splitting hairs between IMR4227 (a pistol powder) and IMR4198 (a rifle powder)? I suppose, but certainly not with powders like RedDot, TrailBoss (in rifle cartridges,) and even my beloved Unique.

I understand the OP is mostly talking about pistol cartridges at the moment, but it seems like rifle cast always sneaks into the conversation...

 

[GeoDudeFlorida]

Ya but your looking at fast burning powders in small volume strait walled cases that are affected by the bullets length/seating depth/case volumes a heck of a lot more that a bottle necked 308w, 30-30 or 30-06 for example.

Apples vs oranges

If you're saying just powder coating a soft lead bullet will allow it to be driven at jacketed bullet pressures and maximum velocities, using slower burning powders on the top-range of the expansion chart, you're just wrong. Or, you're not thinking about you're writing. As was stated WAY before you jumped in the conversation: bullet profile, construction, size, powder choice, bore/groove and the materials all matter as much as if not more than the method of lubrication - and that's all powder coating is, one among many methods of lubricating bullets.

 

[forrest r]

If you're saying just powder coating a soft lead bullet will allow it to be driven at jacketed bullet pressures and maximum velocities, using slower burning powders on the top-range of the expansion chart, you're just wrong. Or, you're not thinking about you're writing. As was stated WAY before you jumped in the conversation: bullet profile, construction, size, powder choice, bore/groove and the materials all matter as much as if not more than the method of lubrication - and that's all powder coating is, one among many methods of lubricating bullets.

How you even came up with that 1 is beyond me????

You quoted what I wrote about case volume in small strait walled revolver cartridges and some how twisted alloy into the mix.

What does "bullets length/seating depth/case volumes" have to do with a powder coat or hard/soft alloy????

 

[forrest r]

If you're saying just powder coating a soft lead bullet will allow it to be driven at jacketed bullet pressures and maximum velocities, using slower burning powders on the top-range of the expansion chart, you're just wrong. Or, you're not thinking about you're writing. As was stated WAY before you jumped in the conversation: bullet profile, construction, size, powder choice, bore/groove and the materials all matter as much as if not more than the method of lubrication - and that's all powder coating is, one among many methods of lubricating bullets.

I keep reading where people post that the pc "powder coating" is a lubricate.

AAHHH, pc ='s powder for the 1st word and coating for the 2nd word.

PC coating is not a lubricate, never has been, never will be. It is a coating that when put on a bullet is considered a jacket. Doesn't matter if it polyurethane base or a polyester base, it coats the bullet/encases the bullet's core. Metal jackets on bullets do the same thing, encase the core. So if pc is a lubricate then metal jackets must be a lubricate also.

 

[GeoDudeFlorida]

I keep reading where people post that the pc "powder coating" is a lubricate.

AAHHH, pc ='s powder for the 1st word and coating for the 2nd word.

PC coating is not a lubricate, never has been, never will be. It is a coating that when put on a bullet is considered a jacket. Doesn't matter if it polyurethane base or a polyester base, it coats the bullet/encases the bullet's core. Metal jackets on bullets do the same thing, encase the core. So if pc is a lubricate then metal jackets must be a lubricate also.

Okey-dokey, smokey. Live and let live is my motto so, have a nice life.

 

[AJC1]

I keep reading where people post that the pc "powder coating" is a lubricate.

AAHHH, pc ='s powder for the 1st word and coating for the 2nd word.

PC coating is not a lubricate, never has been, never will be. It is a coating that when put on a bullet is considered a jacket. Doesn't matter if it polyurethane base or a polyester base, it coats the bullet/encases the bullet's core. Metal jackets on bullets do the same thing, encase the core. So if pc is a lubricate then metal jackets must be a lubricate also.

PC and plating are more similar and if were including lube in the equation the the correct idea is interface materials. Lead alone is a very poor interface material so one of the three other interface materials are used.

Extended testing by fortunecookie45lc has shown to my satisfaction that there is no major advantage to accuracy with PC or traditional lube. If you have contrasting data I would be happy to check it out as these are ever evolving technologies, and to claim forever knowledge would be obtuse.

The case for the lubricated 45-70 PC bullets were in a 32" pendersoli I believe. Any further arguments beyond finding a successful path forward are just that argument with no first hand knowledge.

Any pressure curves showing a higher peak pressure from lead or jacketed would add a lot of value to this debate.

 

[forrest r]

Okey-dokey, smokey. Live and let live is my motto so, have a nice life.

Thank you
Had a pretty good life so far and it just keeps getting better. Semi-retired when I was 36 (semi-retired ='s work 4 months out of a year and vacation/fish/hunt/travel the other 8 months) and retired last year at age 60. Still have my heath, don't need to take any pills, don't have high blood pressure or sugar, ain't over weight. Manage to walk a couple miles a day along with a lot of bike riding (peddle + a couple harley's). Sold the boats and bought a kayak, a lot better for me to stay active along with a hoot to use for fishing, managed to catch these a couple days ago.


Anyway thank you for hoping I have a nice life, been good so far

 

[forrest r]

PC and plating are more similar and if were including lube in the equation the the correct idea is interface materials. Lead alone is a very poor interface material so one of the three other interface materials are used.

Extended testing by fortunecookie45lc has shown to my satisfaction that there is no major advantage to accuracy with PC or traditional lube. If you have contrasting data I would be happy to check it out as these are ever evolving technologies, and to claim forever knowledge would be obtuse.

The case for the lubricated 45-70 PC bullets were in a 32" pendersoli I believe. Any further arguments beyond finding a successful path forward are just that argument with no first hand knowledge.

Any pressure curves showing a higher peak pressure from lead or jacketed would add a lot of value to this debate.

Not trying to argue at all. I'm glad you are relying on what others have wrote/stated rather then doing the leg work yourself.

Myself I'm using a 30" shilen match grade ss bbl chambered in .336" 308w match. I chose a 1 in 14 twist for that shilen barrel. I installed that bbl on my puma rifle along with rebuilding that rifles bolt and setting the head space to what I wanted. I cast and pc my own bullets. I see the results of my testing different alloys, lubes, pc powders, bake times for those powder, testing different temperatures of the baking of the pc powder. I also use a bore scope to actually see what's going on inside that shilen bbl.

None of what I do with cast and pc'd bullets is second hand, told by others, read about, etc. There's nothing wrong with reading about different testing. Just some of it comes up the complete opposite of what I did/test/saw 1st hand.

This is what that shilen bbl looked like after 30 shots using the lee TL312-160-2r bullet that I used traditional lubes on.


That 32" bbl'd 45-70 isn't going to get anywhere near those kind of velocities nor is it going to get anywhere near the 35,000psi+ of that 2600fps load pictured above.

Same lee bullet this time it had a pc coating. Did testing with H335 using 38.0gr, 39.0gr & 40.0gr loads. I started noticing black streaks in the bbl @ 2700fps & yes I check the bbl with a bore scope while testing at the range. This gives me real world results in real time. Didn't see to change much at 2900fps.


Turns out the burnt pc coating is common with several different colors the guy I bought the pc from sells. He had a list of colors that didn't do this when pushing bullets over 2700fps.

Anyway this is the only failure I've seen along with other people that pc their bullets over on the cast bullet website. I did a post on this very subject along with posting pictures. Those that had ran their cast/pc'd bullets over 2700fps chimed in & they pretty much had the same results.

There was no leading in the bbl, the pc didn't wear off down the length of the 30" bbl.

I stand by what I said about a 45-70 having issues with a pc'd bullet. That 45-70 simply can't push the pc'd bullet hard enough/fast enough. Nor can it exert the kinds of pressure on the pc'd bullet that a 308w can. That leaves the rate of twist between the 2 rifles and that shouldn't come into play with a 45-70 and it's low velocities.

You asked, I answered.
Take that lee bullet and compare it to a 165gr non-boattail partition bullet and go head to head with true rifle powder loads. With H335 I using 4 less grains to equal the max velocity of the jacketed bullet/max 42.0gr load.

You could always say that that pc makes 1 heck of a lube and look at how much less friction there is between the pc'd and jacketed bullet.

But for some odd reason the same cast bullet with traditional lube takes 2 1/2grains to get the same max velocity of the jacketed bullet. And as you already stated lead doesn't lubricate very well.