please help with psi again!

[TREERAT]

I just got my Lee hardness testor, so I will know the bhn of the bullets I am trying to shoot! I get a consistent .052 on the scale for a bhn of 19.3 so far so good. what I need help with is at 19.3 bhn Lee instructions say Max psi of 24,703 then I tryed the equation of 1440 x bhn of 19.3 and get 27,792 psi min. and bhn x 480 x 4 = 37,056 Max psi, which one is right? it will make a big difference in the powder and charge I try! right now I am stumped, please help me out!

[mpmarty]

Keep in mind the Lee suggested max load is 90% of the ultimate compressive strength of the tested lead alloy. Don't confuse yourself any more than necessary please, just enjoy the hobby. The variation in individual chambers, cases, barrels and powder / primer lots will be far more than the discrepancies you're worried about. Also, the BH number does not equate to anything more than the surface you tested, at the time you tested it. Cast lead alloy both hardens and softens over time.

[JSnover]

What mpmarty said. Just start with safe loads based on your boolit weight and watch for pressure indications.

[BABore]

Don't fret too much over it. In fact, ignore it. Your reading from the casting rule book and rules are made to be broken. At least I tried to tell my parents that.

Try your boolits a various hardness levels with a decent load. See what it does before jumping in with both feet. I've got a 41 Mag SBHH that will only shoot 20+ bhn boolits into tiny groups. A matching 44 Mag will only shoot 10 bhn boolits well. A 480 Ruger SBH that shoots either hard or soft to the same POA and very, very well. All are full house loads. Got a few rifles that do it too.

I'm currently working with a Marlin 30-30 to 38-55 rebore. I've been working up a 1,800+ fps load for a GC boolit. Things were going very well and I settled on BenchMark powder at XX grains. Multiple 3-shot groups were running an inch and under at 100 yards. Last weekend I loaded up some additional test rounds and things went all to hell on me. My original (accurate) loads used 50/50 WW-Pb alloy, water dropped for 22 bhn. I had some soft lead from a new bucket that I was mixing with the WW's. Turned out that soft lead was closer to 9 bhn instead of 5-6. My last groups were fired with 29 bhn boolits.

Bottom line is you need to keep all them rules in the back of your head and do your own testing. Work outside the box a bit or around the fringes. You'll learn alot more and be able to apply that to other guns. I would have missed out on some super accurate loads had I just went with the psi/hardness rules.

[44man]

BABore is telling it like it is. Quit reading all that stuff and shoot to see what you get.

[lv2tinker]

What Boolet are you casting? Pistol, Rifle???
Need more info.

Here is a link that will tell you all about lead & casting....

http://www.lasc.us/

[JIMinPHX]

Plain base? Hollow base? Gas Checked? The base design changes the workable pressure range even more than the BNH does.

[243winxb]

27,792 psi is correct. http://en.wikipedia.org/wiki/Obturate You do not want your bullets to Obturate. Keep your load below the PSI listed for the BHN. Note that the formula is for solid base bullets. Update > This is better info.You do want the boolits to Obturate , you never want Plastic deformation.
http://castboolits.gunloads.com/showpost.php?p=35425&postcount=7
This whole relationship centers around the elastic limit for the alloy you are using and what the elastic limit is. the elastic limit is the point at which stresses can occur to an object and it will return to it's relative shape. Once you have reached the deformation stage it no longer returns to relative shape. this is a very simplified version of this topic as it pertains to engineering mechanics of materials.

This is meant to be a guide and to keep you within safe/acceptable limits for pressure and alloy for your purposes. Obturated bullets do not mean that the shape has went through plastic deformation, just that it has expanded and stayed within the elastic limits of the alloy.

The formula does not take into account other factors that aide in reducing friction and thus combined forces on the cast slug. As stated above, one member is getting very good accuracy with soft (by most peoples standards) alloys in high velocity loads (for cast anyway).

Another factor not talked aobut is the pressure curve of the powder/cartridge combination. Does it spike quickly (fast pistol powder in rifle size case) or is it a gradual increase (full case of slower powder). Protection of the bullet base can also be a factor, we routinely do this by gas-checking, using lube wads, or fillers.


http://en.wikipedia.org/wiki/Plasticity

[felix]

Wrong! You want the obturation to completely close the bore. You do not want blowby, nor blowback which would exist without the projectile closing the gaps. Most leading occurs because there are gaps. ... felix

I read the web page just now.........
Note the last paragraph in that wikipedia web page. That one is the MOST important info shown on the entire page. ... felix

[243winxb]

Wrong! You want the obturation to completely close the bore. You do not want blowby, nor blowback which would exist without the projectile closing the gaps. Most leading occurs because there are gaps. ... felix

I read the web page just now.........
Note the last paragraph in that wikipedia web page. That one is the MOST important info shown on the entire page. ... felix Bullets are sized to the correct diameter. They do not need to oburtate. If you study Lees BHN chart and the Obturation link page, you will see that Lee keeps the pressure UNDER the pressure where obturation would happen. Go to Hodgdons site , check the pressures for given cast bullets loads. Compare there BHN to the max. load pressures. You will see that Lee and Hodgdons max pressures are under when a bullets obturation would happen.

[TREERAT]

I am haveing a leading issue with my plain base cast bullet with 10.4g red dot. a member here (unique) ran some numbers for me on psi, and said I was running 27,000 psi with this load. now what I am trying to figure out is why am I leading, am I beyound the strength that 19.3 bhn can handle, and need to drop down to 9g and try that. or bump it up to 13g and kick it in the a** so it will obturate more? I am suffering information overload, especially when it differs so much. so I loaded 10rnds at 9g red dot (start load) 10 rnds at 11g unique (start load) and 10 rnds 27g reloader 7 ( start load), and am going to the range tommarrow!!! if I get leading with these I beleive I will need to increase the charge to get more obturation. I will report my findings tommarrow. I WILL FIND SOMETHING THAT WILL NOT LEAD THIS GUN UP!!!!

[longbow]

Have you slugged your bore and/or throat?

You want to size the boolit to at least 0.001" over groove diameter or better to suit the throat. To sort that out you need to slug your bore and throat, and mike the boolits. For example, it doesn't do a lot of good to run a 0.308" diameter boolit through a 0.310" sizer to suit a 0.309" groove. You would need an as cast size of 0.310" or better.

For the most part when I have gotten leading it has usually been due to undersize boolits ~ even with gas checks. If I size a little larger than the groove leading is not a problem even with relatively high pressure loads.

Words from C.E. Harris:

"The mechanical limitations of lead alloys are expressed as a function
of tensile strength and are related to the Brinell Hardness Number.

For most common lead alloys the tensile strength in psi is
approximated by the BHN times the constant 480. Obturation
will be ineffective in loads producing an average chamber
pressure appreciably less than 3 times tensile, and will
cause leading due to gas cutting unless the bullet fits
the chamber throat exactly. Note I cite chamber throat
diameter here and NOT groove diameter.

Likewise, leading is likely to occur due to plastic deformation and failure
of boundary layer lubrication in loads in which peak
pressure exceeds about 4 times tensile strength.

Therefore, the range of optimum chamber pressure must be
related to alloy hardness. As in the following example:

Wheelweight alloy in the as-cast condition at 13 BHN:

13(480) x 3 = 18,720 optimum chamber pressure
13(480) x 4 = 24,960 maximum chamber pressure

For lower chamber pressures use a softer alloy, for high
chamber pressures you will need a harder one. Really
quite simple. "

As a comment though, you can over think things too. There are several posts above to that effect as well. Size correctly, use a good lube, use a recommended starting load and shoot a few more. If leading is still a problem, try a larger boolit. If leading is still a problem, try a harder alloy then a softer one. You will beat it in the end.

Somewhat contrary to the obturation theory, I have found that my .303 Enfield likes oven heat treated boolits even with moderate loads. The harder, the better for that one ~ plain base or gas check.

Longbow

[Bret4207]

Information overload, boy there's a mouthful. Best advice I can give is slow down and work with what you have. Don't worry about Lee's formulas and tensile strength and shear strength and all that stuff. At best those rules, if they even are accurate, vary hugely from gun to gun and even from load to load. As far as obturation goes, it's can help or hurt. If you have an undersized boolit you can use it to help "bump up" a boolit to fit the throat and barrel. But if you start with a large enough boolit obturation becomes deformation and SOMETIMES can do more harm than help.

You are getting leading, that's a problem. So now you need to play the game- change sizes on the boolit. Go as large as you can chamber to start. That works in a lot of guns. If you still get leading then you can try sizing down a thou' at a time if you have that capability. You can seat in the contact with the throat and gradually back it off. You can try no crimp, light crimp, med crimp, etc. You can play with powder.primer combos and try and find a pressure curve your gun likes. You can play with the alloy and HT, keeping in mind when you HT/WQ your boolits there is a significant hardening period that can screw up everything if you forget about it.

There are a lot of what if's. The first "what if" I'd be concerned with is "What if Lee's formula is a whole lot more flexible than he says?". I'd forget worrying about Lee's rules first off.

[joeb33050]

The entire obturation pressure BHN story is pure BS. Harris had no empirical data for the original article, yet the story lives on in many guises. I started investigating hoping that it was true, found it all a sad pseudo-scientific untruth.
To make it worse, we have no reliable method of testing alloy for BHN, and no reliably precise method of estimating pressure.
For those scientists intent on proving the theory true, and I know you're out there, check into Harris's "the load" story. Estimate some pressures and BHNs, and explain that. ("the load" is also far from the best, or even good, reloading info.)
Here's part of the article, from the book:
3.3 CAST BULLET HARDNESS REQUIREMENTS

Bullet Hardness, Chamber Pressure And Accuracy
Theories that bullet hardness and chamber pressure must be matched in some precise and scientific way to allow accurate and leading-free shooting have been presented by some authors and repeated by many others since 1984.
To find out about these theories, I searched the literature back to the sources of the theories and tested the theories against pressure-hardness combinations used successfully.
I concluded that these theories are contradicted by data. It is certainly true that higher velocities require harder alloys in rifles. But the notion that best accuracy is found at a specific pressure/hardness intersection and diminishes as hardness is increased or decreased from that junction is not borne out by the data.
If it were true that this pressure-hardness relationship were important for accuracy, then a means of testing alloy for hardness and another means for estimating maximum chamber pressure would be necessary.
Here is a table showing the results of hardness testing of bullets I cast out of one pot of wheelweights in a 2 cavity mold on 1/1/2006-one cavity with a dot and the other without. Six bullets were sent to each of the volunteer testers who tested for BHN on 1/11/2006.
The variation from bullet to bullet, cavity to cavity and tester to tester suggests that precise estimation of BHN using reloader-type testers is not possible.

Then there is the question of pressure estimation.
I think that I understand that velocity is a function of the area under the pressure curve-it's not intuitively obvious to me that the relationship is linear. I imagine acceleration varying during the travel of the bullet.
"Quickload" is a computer program that estimates pressure and velocity upon entry of load data.
Quickload seems to accurately predict velocity-we can easily measure velocity.
It is not clear to me that the program accurately predicts maximum pressure, mainly because we don't have the equipment to measure pressure and check the Quickload predicted values.
It does not provide for inclusion of primer type or brand in the calculations.
Handloader, August 2005, "Velocity and Pressure" by John Barsness.
The author cites "Any Shot You Want", the A-Square loading manual concerning variations in pressure with changes in primer. From that manual, on pg. 65 the table "Primer Experiment" shows: 7MM Remington Magnum, 160 grain Sierra boat-tail, 66.0 grains of Hodgdon H-4831 and Winchester cases.
CCI 200 (standard) 3011 fps, 54,800 psi
Rem 9 1/2 M (magnum) 3041 fps, 59,300 psi
CCI 250 (magnum) 3039 fps, 61,500 psi
Fed 215 (magnum) 3036 fps, 61,400 psi
Win WLR (standard) 3024 fps, 64,400 psi
Win WLRM (magnum) 3045 fps, 67,600 psi

The author then performed a test on a ".300 Winchester Magnum with a 23-inch barrel, the load a 180-grain Nosler Partition with 75.0 grains of Hodgdon H-4831 in Winchester cases."
Fed 215M, 2924 fps, 63,800 psi
CCI BR2, 2920 fps, 55,800 psi
Win WLRM, 2991 fps, 70,100 psi

It is clear that pressure varies greatly with primer, while velocity varies much less.
This article suggests to me that Quickload maximum pressure data may be suspect in some cases.
Without pressure-measuring equipment I think that estimating maximum pressure may be difficult, particularly for the novice.
If the reloader cannot estimate alloy hardness precisely, and if pressure cannot be estimated precisely, then attempting to match hardness and pressure for maximum accuracy-even if the theories were true-is difficult to impossible.

On to the data.
This paper uses three sets of data to look at real-life pressures and BHNs, and test the theories with this data. .
The "Wosika" data is from Ed's article in The Fouling Shot (TFS) 170-12, with data in ksi = thousand psi.
The "Bischoff" data is attached; the pressures were calculated by John Bischoff using Quickload. Pressures in psi, converted to ksi on the graph..
The "13 Grains Red Dot" data is attached. The pressures were again calculated by John Bischoff using Quickload. Pressures in psi, are converted to ksi on the graph..
While none of the members of the two sets of theories are borne out by experiment or data, they have achieved a life of their own, and are now embedded in the literature.
All the theories use formulas including the Brinnell Hardness Number (BHN) of the bullet.
The BHN is the ratio of:
the force applied to a ball in contact with the test specimen for a specific time,
to: the area of the "dent" made in the test specimen by the ball. This dent is called, by geometers, a "spherical cap".
The force is measured in kilograms and the spherical cap area is measured in millimeters squared.
The earliest theory starts with converting the BHN from kg/mm^2 to pounds per square inch, psi. A bit of arithmetic leads to the fact that multiplying BHN by 1422 gives BHN in psi.
Then the mistake is made, and this psi number is stated, incorrectly, to equal the compressive or tensile or ultimate compressive or yield strength of the material. None of these are true.
So, for example, we might have a wheelweight bullet of BHN = 12. Multiplying 12 by 1422 gives us 17,064 psi, a precise and quite irrefutable number. Not, however, any measure of the strength of the alloy.
Now, the theorists need to do something with that 17,064 number.
Chamber pressure comes in thousands of psi, and looks like the (BHN X 1422) number.
Enter "Obturation", the swelling or bumping-up of a bullet by the burning powder gasses on and shortly after ignition. The theorists now combine chamber pressure, obturation and the BHN psi number with one or more explanations of what is happening to the bullet on firing, and we're presented with these prescriptions.
#1 Chamber pressure must equal or exceed (BHN X 1422) for obturation to occur, else leading and poor accuracy result.
#2 Best accuracy occurs when chamber pressure = (BHN X 1422 X 90%), else leading and/or lesser accuracy result.

The second set of theories is based on the relationship between BHN and tensile strength for lead alloys.
For example, Table 5 in ASM Handbook, formerly 10th edition, Metals Handbook, Volume 2, 1998, "Nonferrous Alloys and Special-Purpose Materials".
The theories make use of the fact that (BHN X 480) is an approximation of the tensile strength of the lead alloys in the table.
(A regression analysis of the entries in this table for which there are both BHN and tensile strength entries yields: ksi = -.33 + .498 X BHN, with R^2 of .964. Some 96.4% of the variation in hardness is connected to the variation in BHN. The approximation using 480 is reasonable.)
With this (480 X BHN) approximation for tensile strength we're not in the chamber pressure area.
For example, with a wheelweight bullet of BHN = 12, multiplying 12 by 480 gives us 5760, a not-very-like-chamber-pressure number.
If a multiplier is introduced, such as "3", the expression is changed to (BHN X 480 X 3), and 12 X 480 X 3 = 17,280, a precise number in the chamber pressure area.
Now, we have to do something with that 17,280 number.
Get out "obturation", add chamber pressure and the BHN/480/multiplier formulas, and some explanations of what happens to the bullet on or just after firing can be imagined.
These are the prescriptions for the "480" family of theories:
#3 Chamber pressure must equal or exceed (BHN X 480 X 3) psi, else leading and diminished accuracy.
#4 Chamber pressure must be between (BHN X 480 X 3) and (BHN X 480 X 4) else leading and diminished accuracy.
#5 Chamber pressure must be between (BHN X 480 X 3) and (BHN X 480 X 3 + 10,500) psi else leading and diminished accuracy.
The graph below shows all of these prescriptions, and all of the data points representing the "Wosika", "Bischoff" and "13 Grains of Red Dot" data. While some of the data points-loads are within the prescriptions, most are outside the prescriptions.


It is somewhere between difficult and impossible to prove that theories such as these are absolutely incorrect, even though the foundations for these theories can be shown to be flawed or without data supporting them.
However, the data-theory comparisons above show that there are a number of successful loads with BHN-Pressure intercepts outside the theory prescriptions. Then we are left with two possible statements:
1. The theories are not correct, or
2. One or more of the theories is correct, and many skilled shooters are not operating in the correct BHN/Pressure range.
I favor 1.
Ed Wosika suggests that since this data deals mostly with velocities under 2000 fps and associated low pressures, that we not make any statements about the BHN/Pressure relationship above 1900 fps and higher pressures. This is "extending the conclusions beyond the data". Ed is correct and I agree.
Ed also suggests removing the few high pressure BHN/Pressure pairs. I refuse to remove data from a set for any reason. The reader is free to discount these data points.
References
1984 "Jacketed Performance With Cast Bullets" by Veral Smith
TFS 81 Sep-Oct 1989 "Match Wheelgun And Load Preparation"
TFS 86-3, July-August 1990
1991 "Bullet Making Annual" article, Pg 17
TFS 96 Mar-Apr 1992 "Technical Dialogue"
TFS 102- 4 Mar-Apr 1993Interpolating Pressure for Correct BHN
TCB 116 Jul-Aug 1995 "More on Chamber Pressure and BHN"
TFS 131-10 Jan-Feb 1998 "Still More On Chamber Pressure And BHN"
Handloader 226 December 2003 , starting on pg.6,
2003 Modern Reloading, Second Edition, Richard Lee

[TREERAT]

all this advice is why I am going to forget all the equation theories for now, and just go to the range with starting loads and see where I stand. I have loaded for 5 different hand guns (thousands of rounds) with no problems! I have loaded several thousand 30-30's for a contender carbine from 1,100 fps to 2,300 fps with 3 different powders and never got leading. and serveral hundred for a 45-70 from 900 to 1700 fps with no leading. back then I did not know all these equations, not even bhn, just poured acww and stuffed em in a case and it almost always worked. since every thing always worked, the only thing I really learned was the 30-30 wanted .311 sized instead of .309! and accuracy fell off after 2,100 fps. so you can see I am not new to this, just kinda went stupid with all the new information I have learned, which I beleive has hurt me more than help! = information overload!

[BABore]

I would be trying a different powder. The estimated or book pressure is peak pressure. It doesn't tell you when/where it occurred in the barrel. Red Dot is a fast powder that hits the boolit base very hard and fast. Depending on the gun/caliber, that may or may not be a good thing. Should it be in a rifle, with a oversized case neck area, you can actually slam the base hard enough to cant the base. This would screw things up big time. A slightly slower powder, like Unique, would get the boolit a bit farther out of the case before it peaks. Yes, you can get leading from powder/primer choices, independent of alloy.

My buddy and I both used to shoot a 311041 with 13 grs. of RD out of our 30'06's. Mine is a Reminton 700 with a well worn (long) throat. His is a 4 groove 03'. I had no problems and good accuracy. He had good accuracy, but every once in a while he would split the case at the juction of the neck and shoulder. As he had to seat the boolits with the GC/base below the shoulder, I figured that the fast RD powder was excessively obturating the base in an unsupported condition. The boolit was mushroomed at the base and was trying to pull the lips off of the case. Pure theory on my part, but, switching to a slower powder eliminated the problem. All boolits were 22 bhn.

[felix]

What happens to a projectile immediately outside of its case? Do you shoot with less than a ZERO clearance, like with a case having a neck thickness of ZERO? A Canadian company, about 20 years ago, tried to develop caseless ammo for the military and could not get it to work in practice with current gun styles. The best we can do is to fit the projectile with the throat (freebore + leade) exactly, but in practice we never do because the obturation would necessarily be thwarted more to the chamber than necessary. ... felix

[243winxb]

I am haveing a leading issue with my plain base cast bullet with 10.4g red dot. a member here (unique) ran some numbers for me on psi, and said I was running 27,000 psi with this load. now what I am trying to figure out is why am I leading, am I beyound the strength that 19.3 bhn can handle, and need to drop down to 9g and try that. or bump it up to 13g and kick it in the a** so it will obturate more? I am suffering information overload, especially when it differs so much. so I loaded 10rnds at 9g red dot (start load) 10 rnds at 11g unique (start load) and 10 rnds 27g reloader 7 ( start load), and am going to the range tommarrow!!! if I get leading with these I beleive I will need to increase the charge to get more obturation. I will report my findings tommarrow. I WILL FIND SOMETHING THAT WILL NOT LEAD THIS GUN UP!!!! While antimony is used to harden the bullet, the mixture of tin is critical, for while antimony mixes with lead in its molten state, it will not remain mixed when it solidifies. If tin were not added, we would have pure antimony crystals surrounded by pure lead. A bullet of this type , while it feels hard , would certainly lead the bore and eliminate all potential for accuracy. In a lead-tin-antimony mixture, the antimony crystals will be present just the same, but they will be imbedded in a lead-tin mixutre. As the bullet cools the tin will form around the antimony-lead keeping your bullets from leading the bore.

[GP100man]

where is the leading occuring , smeared or strips???caliber???

GP100man

[243winxb]

all this advice is why I am going to forget all the equation theories for now, and just go to the range with starting loads and see where I stand. I have loaded for 5 different hand guns (thousands of rounds) with no problems! I have loaded several thousand 30-30's for a contender carbine from 1,100 fps to 2,300 fps with 3 different powders and never got leading. and serveral hundred for a 45-70 from 900 to 1700 fps with no leading. back then I did not know all these equations, not even bhn, just poured acww and stuffed em in a case and it almost always worked. since every thing always worked, the only thing I really learned was the 30-30 wanted .311 sized instead of .309! and accuracy fell off after 2,100 fps. so you can see I am not new to this, just kinda went stupid with all the new information I have learned, which I beleive has hurt me more than help! = information overload! The Zinc and Bismuth & other foreign metals getting into the alloy have changed what we have worked with for over 30+ years without problems. Very little tin in wheel weight now. The Bismuth when in an alloy can cause strange things, like after 3 or more days the diameter of sized bullet will have gotten bigger by a few .001" 's . They grow bigger over night with a high percent of Bismuth.

[TREERAT]

see new post- results as promised .358 win

[leftiye]

I wish some people would get over the 1422 X BHN thang. We all understand that it sounds like it should work that way, but often it doesn't. Thas why in addition to the boolit being over bore diameter it often helps if the bolit obtturates a little to finalize the seal. Lose the gas seal and you get leading and poor accuracy. No matter how hard your lead is! Especially in revolters, a softer boolit that can bump up a little (AND correct sizing) and pressures/velocities just in the "grey wash" area often produces best accuracy.

[Slow Elk 45/70]

OK TreeRat, I'll play, where did you put the "New Post" ??????[smilie=1:

[243winxb]

http://castboolits.gunloads.com/showthread.php?t=52136 here he is , found him lol.