cast bullets and high velocity cartridges

[vzerone]

So you say they have pushed it up. Let's take a rifle and caliber that has defeated you and one that you have recently posted about in at least two forums. The 6.5x55 Swede. You even said you are going to reside to shooting the 1400 to 1800-1900 fps with it and be happy. Now my "cuz" flat out beat your threshold with his Swede using the 130 Kurtz bullet. I'd say a 1/2 inch group at 100 yards at nearly 2300 fps in that fast twist isn't just pushing up the threshold. You do realize that a threshold is no moveable, or least by not much? How about a door threshold? Ever stop to think why it's called that? Before you address the above Swede shooting that test was repeated many times, just not photographed nor talked about. Also not photographed or talked about is the 180 grain 30 Sil at jacketed velocities into very small groups none larger then 1/2 inch and out of both 10 twist, 11 twist, and 12 twist. 45 2.1 has been doing it regularly out of the Ruger Scouts. Cuz actually saw that happen and also shot almost the same small groups with it.

Here's another recent shot rifle that just didn't push up your threshold, but soundly beat it again:
Rifle: 1909 Argentine
Groove: .3110
Brass: 30-06 Rem sized down to 7.65 Argentine with no special work done to it.
Powder: Alliant RL-22
Charge: 45.0 grains
Primer: CCI Large Rifle Standard (I don't like them)
Temperature: 44 Degrees
Humidity: 43%
Wind: Less then 5 mph head on.
Attitude: 2200 feet
Shots Fired: 10
Average Velocity: 2239 fps
ES: 68
SD: 25
Group Size: 1 inch
Lube: Soap Lube
Gas Checks: Hornady
Chrono Distance: 9 feet 1.5 inches

Then their Cuz's little SAKO 7mm-08 shooting the LEE 130 grain bullet (a non-fitted bullet) into 3/4-1 inch groups at 2640 fps.

You have a selective memory Larry.

I will address your "If there is not an RPM threshold then how is it most cast bullet loads with fast and medium burning powders lose accuracy when they exceed 140,000 RPM" That's a well duh question. To reach that rpm range you have to hit the bullet pretty hard and you know very well that the fast powder is especially not the one to do so with. Do I have to tell you why? So according to you all fliers are because of the threshold? You ever think that those fliers may be from poorly cast bullets. That brings up the member casting better then your 1.1 grain variance in recent posts in more then one place on this forum. You know very well that there are many things that can ruin or prevent a bullet from starting straight into the bore.

Waco done very well for being a young fellow and with a mediocre rifle (not so much the rifle, but it's terrible throat) for the first time out doing this.

Let me know when you can cast all your bullets within a .1 grain variance. Don't forget you're the one that posted your variance weights in three forums that I know of, so I'm not making inane statements....you made them.

[vzerone]

I think you fellows need to realize I am reading this thread and I feel all of you are entitled to express your theory but the running another person's theory down will stop now. Go prove your theory post your finding and leave the nitpicking one another out of cast boolits.

You can't prove that theory with cast bullets Preacher Jim, they just aren't perfect enough nor strong enough no matter who casts them. I would never ever attempt those tests with cast bullets and we all know the reason why. None of the things I posted are lies and most the data was posted by that person. I reckon Bryan Litz isn't good enough to hear that you can't do the three rifle twist with your rifle, a friends rifle, and a third friends rifle.

[vzerone]

I forgot to say I'm done.

[Larry Gibson]

The 6.5 never defeated me. I thoroughly tested it and was quite pleased with the results. The velocity level I shoot it at now (I currently have three 6.5 Swede's, all with military barrels) is the one where the best accuracy is found and simply because that is what I choose to do. Accuracy is all I'm concerned about with cast in the 6.5 Swede because, other than for small game, I won't hunt with it so velocity is not any issue. Joe, who you call your "cuz", did not prove anything as no one else could duplicate the velocity or the accuracy he claimed. I duplicated his load with his own bullets (he sent them to me) and still fell almost 200 fps short in velocity. Here is a picture of the 100 and 200 yard 10 shot groups. Note the non-liner group expansion between 100 and 200 yards demonstrating that, even at the much lower velocity, than he claimed the bullets were over the RPM Threshold. Joe always claimed 5 shot groups accuracy but at 100 yards that still isn't bad. Defeated.......hardly.

Attachment 219822


We have been hearing about “bug hole groups, not larger than ½” and moa” for a long, long time from you and the others you mention for a long, long time. Yet you fail to provide any sort of proof by posting groups or at least having your “feats” of incredible velocity and accuracy witnessed by members of this forum who have requested to do so. Lot’s of typed out claims but little or no actual documentation. I have had an open invitation for anyone to come and see me shoot and to shoot my rifles. There have been numerous CBF member come here and shoot my rifles and see what really can be done with cast bullets at high velocity. I have also won several CBA military rifle matches the last couple three years including two state matches. If you can in fact shoot such such a 1” group with your M909 you could be a national CBA champion. But both your “cuz”, 45 2.1 and several others have been told that and asked to compete. All sorts of reasons why they wouldn’t though and I’m sure you’ll also tell us why you can’t……..

Who says a “threshold” can’t be moveable…….you just makeup definitions to suit your own purpose. A threshold can be moved. A threshold definition I used when I coined the term for this application is simply, according to Webster’s, “the point at which a physiological…..effect begins to be produced”. That being the loss of accuracy due to the adverse effect of centrifugal force on imbalances in the bullet in flight. BTW; Litz agrees.

My memory is not selective. I deal with facts as presented by actual testing. Here is the 311291 in a 10” twist .308W using 4895, a medium burning powder, at 1850 fps (under the RPM Threshold) at 50, 100 and 200 yards. Notice the almost liner group expansion.

Attachment 219825

Here is the same except the velocity is 2350 fps. Note the poorer accuracy and non-linear group expansion evidenced because this load is way above it’s RPM Threshold. There’s your “wild” bullets that are, in fact, over the RPM Threshold BTW.

Attachment 219826Attachment 219827

Now here’s using a properly designed cast bullet for HV and a slower burning powder in the same rifle which has a M118 chamber and other than sizing to the throat neither bullet was “fitted”. The velocity of this load is 2267 fps out of the very same .308W rifle. This load was also the one used to shoot 2 moa ten shot group at 500 yards. Thus is also holds linear group dispersion and is not above it’s RPM Threshold even though the RPM is 163,300. It still hold sub 1.5 moa up through 2350 fps, however, when loaded to 2400 fps I get the same 30% “flyers” opening the group to 2+ moa at 100 yards that Waco got. in the 2300 - 2400 fps range is where this load with the slower burning powders goes over its RPM Threshold. Jacketed velocity for a comparable 165 gr jacketed bullet would be 2650 – 2700 fps.

Attachment 219828

Thus even though I have pushed the RPM Threshold up it still does not equal jacketed bullet potential. Neither did your “cuz’s” 6.5 loads. Here's the 100 yard and 200 yard accuracy with the 6.5 bullets "cuz" sent me with his exact load out of the M96 even though it produced almost 200 fps less than he claimed. I was certainly impressed.......

Attachment 219823Attachment 219824

These test results are representative of the many, many test results I have posted which demonstrate the RPM Threshold is, how it adversely affects accuracy and clearly demonstrates how the RPM threshold can be pushed up, exactly as I have said for several years now.....

[Preacher Jim]

theory's, they are just that until people we do not know duplicate our results.
I buy my Krieger barrel blanks 5 at a time 2 are bug hollers, 3 I sell as varmint barrels. I have found that the average rifle if you line up 5 and use the same exact ammo will group differently. the factors that determine duplicating what is posted here are close to impossible because of several factors, 1. brass differences, barrels, powder lots, bullet mold variations. lube sizer die differences, humidity, wind, temperatures, and most of all the fellow who pulls the trigger.
in many ways the debates on all these theories boils down to I say, all of you have good information that should help a newbie in pursuit of better shooting but you destroy that with the personal attacks and arguments. Jack Webb used to say," just the facts mam". fellows report your research admit it is just what you found with your shooting and leave the proof to those who follow in your footsteps to prove.
you can quote whoever you want to enhance your theory but it is not gospel till it stands the test of time.
RPM is a proven fact, it you over rotate a round object any imbalance causes wobble or instability to surface. Where is the threshold, where it occurs. All bullets are different, I can try hard to find the sweet spot for my boolit or bullet but guys your finding will differ with your bullets.
enough said. stop the nonsense and help the ones coming behind us to shoot better.

[popper]

I haven't been able to notice/measure ANY change in dia. when using Cu in the alloy - but I don't have any tin in it. I sent some alloy and some 31-165B to Waco to test but haven't heard anything yet. Hopefully he will test the XBC & 165B in his rifle. I sent him some PCd too.
300BO carbine: Hornady 150SP gives 1950 & .3" c-c @ 50, 142C (1or2% Cu) is 2112 (avg 47 ES) .8" c-c @ 50.
LR308 carbine: same alloys give 2550 with H4895(appears to be peak of fps) & MOA @ 200. The 150Sp and 168 Amax do the same in the rifle LR308, 2700 fps.
As I've stated before, rotational energy (gyro precession effect) is what causes the RPM threshhold. Weak alloy, wind, bad cast - all the same.

[TXGunNut]

One thing that bothers me about this "threshold" debate is that this "threshold" is a matter of physics; the study of physics is governed by laws and these laws don't change. It's very real, whether we understand it or not. We can't move this threshold any more than we can change the laws of physics. We CAN change some of the dozens of variables that determine where this threshold is found. How we manipulate these variables (when possible) is what makes this line of conversation and research beneficial. Identifying these variables and learning how to work with them should be the focus of this debate, IMHO.
The other thing that bothers me about this debate is the personal attacks. I don't know why this topic attracts this type of behavior but I'm tired of it. As a group we have the ability and resources to do an awesome amount of research and testing but we have to wade through the personal attacks to follow an interesting topic. Let's play nice and figure out how to make better boolits, OK?

[Larry Gibson]

"We can't move this threshold any more than we can change the laws of physics."

Depends on how we define the "Threshold". In this instance if we want to give the Threshold a numerical number for all bullets then it doesn't move. However, if the Threshold is defined and instead based on that point where the centrifugal force causes the bullet to depart from the line of flight then the Threshold is moveable as in when we use a harder/stronger alloy, use a better designed cast bullet, slow down the acceleration time curve, put a PP on the bullet or use a copper/steel jacket on the bullet. All have a threshold, only one has a higher threshold than is obtained safely in most cartridges. It's why a 311413 cast of COWWs isn't going to be accurate at 2100 fps out of a 30-06 but the 311291 can be. It's why the 311291 isn't going to be accurate at 2800 fps out of that same 30-06 but a 180 gr Hornady SP can be.

Nothing personal intended nor am I calling out anyone. Just clarifying my own definition of the Threshold. I do not, and have never, considered it to be an absolute "limit" as many misconstrue it to be. Again, just clarification.

[Bazoo]

I've asked myself similar questions with regard to caliber.... and for that I normally stick to calibers that can deliver their full potential with cast projectiles. Im starting to be of the mindset though, that I could purchase jacketed bullets when desired or needed for longer range or more power, all the while shooting many thousands of cast bullets and enjoying the savings.

[TXGunNut]

Thanks for the clarification, Larry. I have to dumb many things down so that I can understand them. I call these things you (and others) do with alloy, design, pressures and even tighter quality control "variables" because they affect where this threshold is found. On top of that there are environmental and other variables we have no control over. I don't think this threshold is a finite number, it's a point where undesirable behavior is observed as a result of many factors. I don't pretend to fully understand the effects of all these variables but I know that you are well aware of them and are working to understand them. I appreciate what you're doing, Larry.

ETA: In other words, IMHO the destination is not as important as how you get there.

[MT Gianni]

" Merriam Webster Definition of threshold
1 : the plank, stone, or piece of timber that lies under a door : sill
2 a : gate, door
b (1) : end, boundary; specifically : the end of a runway (2) : the place or point of entering or beginning : outset on the threshold of a new age
3 a : the point at which a physiological or psychological effect begins to be produced has a high threshold for pain
b : a level, point, or value above which something is true or will take place and below which it is not or will not."

The definition of this by Merriam Webster is probably why there have been so many pitzing contest here over this. The English dictionary clearly calls a "threshold" an immovable object. If one member doesn't no wonder there has been so much confusion.

[Larry Gibson]

What I see in that definition is that a "physiological effect" or "boundary" ....."the place or point of....beginning..." As I have defined it the RPM Threshold it is that point where the centrifugal force causes the bullet to depart from the line of flight and inaccuracy begins. That point is where the physiological change in the bullets flight crosses a boundary where accuracy begins to fail and inaccuracy begins. If you change the variables as I mentioned in the prior post you can change the threshold, "boundary" or whatever you want to call it.

Eight+ years ago I was asked, no I was goaded, into naming my "theory" (I didn't then and still don't think the theory is mine because I simply began to understand it from reading what other(s) said about it years ago). So I named it the RPM Threshold just to satisfy the dissenting members here. Now after 8+ years some of you dissenters want to argue the semantics of the name........ why don't you do something constructive and prove the theory itself wrong with actual testing instead of just criticizing the name? You all don't like the name? Fine with me, it's easy enough to rename.....how about the "RPM Moveable Boundary Theory"? How about the "Point Where RPM Causes Inaccuracy"? How about the Cause of Inaccuracy in the Best of our Cast Bullets"? Will any of those name changes or any name change have any affect on any bullet in flight? No it won't change a thing. Point is we can argue all the semantics we want, change the name, etc. but that does not change the fact of what actually occurs to a cast bullet in flight.

Hey, as Preacher Jim said; "fellows report your research admit it is just what you found with your shooting and leave the proof to those who follow in your footsteps to prove." I have reported my research many times over the last 8+ years. Anyone having any research, of actual test results, of any ternary alloyed cast bullets (that's a lead, antimony, tin alloy with possible inconsequential traces of other elements like COWWs, #2 alloy or linotype) that proves me wrong we'd all like to see the actual results?

[TXGunNut]

With apologies to Larry I'd like to say I think the 3b definition cited above fits Larry's observations. I think the mistake we make is that we want to know if a boolit at X velocity with a twist rate of C is exceeding the RPM threshold. As I understand it the correct answer is "yes", "no", or "it depends...". It wasn't my intention to attack Larry or cast aspersions upon his excellent work. I just wanted to encourage constructive debate on the subject and I'm truly sorry if I didn't come across that way.

[Larry Gibson]

TXGunNut

No need to apologize, Your posts have been insightful and helpful to the conversation. When I first developed the RPM Threshold 8+ years ago it initially was based on the use of traditional cast bullets of a ternary alloy (COWWs was the alloy most used and discussed back then) loaded with fast to medium burning powders from, say, Unique up through 4895 in burning rate. It's with those the where the original RPM Threshold generally is between 120,000 and 140,000 RPM. No limit there just general figures with a potential +/- of 20,000 RPM. That's where the "yes, no or it depends" comes into being.

Some think I dreamed the Threshold up all at once and it was locked in stone. I didn't and it wasn't. I had been pondering and testing for numerous years based on reading over the years before. I didn't know every thing about the threshold then (several other cast bullet shooters have been actively conducting tests also) and we have learned a lot since then. There still is a lot to learn. The more we tested the more we learned how to push the Threshold up....or down. We learned through extensive testing of ternary alloy cast bullets just how fast we could push them, in numerous various twist rifles, and maintain linear accuracy at extended ranges......now out to 500 yards (with a 10" and 14" twists) maintain 1.5 to 20 moa accuracy and 600 yards with a 16" twist while maintaining 1 to 1.5 moa accuracy.

Now there has been sufficient testing done in the development of quarternary alloy cast bullets that we are interested in seeing how far we can push the RPM Threshold with those using badgeredd's alloy. Disregarding the quibbling the last 8+ years it has been a very interesting learning journey. I'll be headed to Montana the end of the month for some PD shooting.......mostly with two 223s and a 22-250. However, I'm taking my 30x60 XCB along to give it a try with the 30 XCB bullet at 2900 fps. Should be interesting to see the results. When I get back I plan on casting some quarternary alloy bullets (30 XCB, 311466, 311291 and 45 2.1s 30 Sil) and testing them.

[TXGunNut]

Thanks, Larry. I don't understand all you (and others) are doing on this threshold project but I have a basic understanding of physics. And I agree, you didn't invent the threshold or whatever folks choose to call it. The laws of physics have been around forever and will govern the actions of inanimate objects long after we're gone. You recognized and sought to further define this threshold. People have been dealing with this threshold since they discovered a soft heavy metal made a better projectile than a random rock.
Carry on! I'm not sure how I can use your quarternary alloy boolit performance data to improve the performance of my hunting boolits but I'll step back into lurk mode and try to learn something.

[TXGunNut]

Is there a point to using cast with cartridges such as 308 win since it is capable of so much more velocity than what can be utilized with cast hunting velocities. I know people have gotten velocities with bullets that match jacketed velocities but in hunting wouldn't they just fragment heavily on impact

My apologies for continuing the hijack of your thread. To address your question there is indeed a point to using cast boolits in cartridges designed for J-words. First of all you'll be using a boolit YOU made and there's nothing like the feeling of attaining a clean kill with a boolit you made. The fragmenting issue is an alloy issue. It's easy enough to address but others here (Fryxell, Gibson, et al) have addressed it much better than I can. Lastly boolits perform and transfer energy (shock) differently than J-words. A cast boolit does not need to achieve the same velocity as a J-word to perform adequately on game. Quite honestly I prefer boolits in a larger caliber than .308 but I know they work given the proper boolit design, alloy and of course, shot placement.

[Larry Gibson]

Interesting to note there is a sticky at the top of this sub-forum started by Dan Walker [http://castboolits.gunloads.com/show...rifle-boolits]. He uses the term "threshold" also but I see none of the critics questioned the use of that term there......

There are several posts in that thread/sticky regarding RPM. In post #17 I explain, again, the RPM Threshold. My definition has not really changed since then. That was 4 years ago. Still in that 4 years we have learned a lot about pushing ternary alloyed cast bullets to true jacketed bullet velocities. It would be refreshing to hear from others who have run into the RPM Threshold with traditional cast bullets using 7" to 12" twist rifles of any cartridge?

Back to the thread topic; I have tested #2 alloy cast 311041 bullets at an impact velocity of 2600 fps out of a 14" twist rifle in sopping wet newsprint. They did expand and some of the expansion petals did slough off but the bullets did not shatter. Penetration was 14 to 18" if I recall correctly. Even at 300 yards the 30 XCB cast of #2 alloy, when shot at 2900 fps with an impact velocity of 1800 fps +/- into the same media, there was still some expansion.

[Cosmic_Charlie]

For the kind of plinking and hunting I do cast boolits are perfect. Working on loads for a Ruger American Compact in .308 and I figure when I settle on one I will sight the rifle in at 50 yds. and call it good. Same for my 30-30 and Henry BB. Looking forward to putting a cast boolit through a perched crow and also a deer this fall, maybe a beaver or two. I like the mellow recoil impulse of 1700 fps loads. Now if I lived out on the prairie I might not mess with cast at all in rifles.

[500Linebaughbuck]

i'm like TXGunNut is, i understand basic physics( well, i do mean basic ). i kinda understand what Mr. Gibson does and i do congratulate him. its nice to see someone who does deliver cast boolits to their maximum. be it max velocity or a low speed, high crushing bone load. the RPM threshold thing is not something i should do. i'm happy with my low velocity boolits and placing them a 125 - 150 yards. the deer aren't happy, but i am. Mr. Gibson, i like the work you do on cast boolits.

[popper]

THis 'theory' discussion is silly. I learned that in 3rd grade, spinning thumb tacks on the school desk. They hit something and take off at weird angles. Run them slow enough and they begin to wobble and fall over (often taking off in some direction). Unbalance with some nail polish or just blow on it - zoom. It exists (for a given boolit, fps,alloy, etc.) get over it! Does you HV boolit turn sideways @ 20ft and destroy itself (turn to dust)? I use Cu enhanced alloy (RNFP) to get HV with med speed powder, it works fine (to 200 yds so far). I will use jacketed for long range shots (usually moving pigs) as I can't gauge range that good and the better BC makes the difference in DROP (yea, fps too). Yes, I hit steel @ 200 (1700 fps?) and found one sliver of boolit. My conclusion is it 'broke' off the nose as the nose slumped. I use this terminology as from experience of a 40SW that hit stone. 3/4 of the TC nose was >0.4 but a 'proud' part was still TC nose.
Sometimes the words we use aren't quite 'correct' but the best we can find.