Do I need to go much higher on BHN for better accuracy in my Pedersoli buffalo rifle?

[JimGnitecki]

I had great accuracy with a specific Lee bullet mold and a Lead alloy with BHN = 10, in my Pedersoli Sharps .45-70 replica, shooting a 485g bullet when shooting at 100 yards. But, that bullet design became unstable enough by 150 meters = 164 yards that it would not group at all.

With the new slightly heavier bullet mold I am using now (497g and very slightly different ogive), versus the older mold, the bullets are stable now at ranges beyond 100 yards. The new bullets do group well at 164 yards, but not PROPORTIONATELY as well as the older bullets did at 100 yards. i.e. Accuracy is inferior on the new bullets on an MOA basis.

The bullet alloy I have been using is wheel weight based, with 1% more Tin added, resulting in that BHN = 10, which is a relatively soft bullet. I had used the BHN = 10 alloy successfully at 100 yards with loads whose peak pressure was 19,000 psi or lower. But now, I have realized that avoiding transonic bullet velocity ranges is more important than I knew, and have stepped up velocity to a 1350 to 1375 fps range, and that velocity range is supposedly (per load tables) generating peak pressures as high as 28,000 psi.

I ran out of wheel weights, and so have switched to using an alloy, made from pure Lead, Rotometals Super Hard ingot, and pure Tin. I mixed these to generate an alloy whose BHN = 12.5. I want to see if the BHN = 12.5 will improve the accuracy. Since I am powder coating versus using conventional lubricants, I have not been getting any barrel leading at all with BHN = 10. But, Richard Lee devoted an entire chapter in "Modern Reloading" to how BHN is important in optimizing accuracy, and how bullet BHN should be "matched" to peak pressure, with peak pressure being about 90% of bullet strength.



On that basis, the BHN =10 alloy I have been using is "way too soft", even though my use of powder coating versus conventional lubrication gives me a lot more leeway on bullet hardness.

But if Richard Lee was correct in his stance, then BHN = 12.5 is still not going to be enough of an increase in hardness given the load that I am using now. The Richard Lee data in Modern Reloading seems to indicate that a BHN as high as 22 might be ideal.

Since I already have made a small test batch of bullets using the BHN = 12.5 alloy, I am planning to do some range testing to see if accuracy remains the same or gets better. If it gets better, which the Richard Lee experimentation predicts it will, I will next test an even higher BHN alloy, and work my way upward.

But, I have consistently read on online forums that most of the 45-70 replica "buffalo rifles", and Pedersoli rifles specifically, normally do not require BHNs anywhere near that high. Is this because most buffalo rifles are being shot at lower velocities with low peak pressures (much lower than the 28,000 psi the load tables say I am at when shooting a 500g bullet at 1350 to 1375 fps)? Or, is it because conventional cast bullet lubricants simply don't work well at 1400 fps velocities and so buffalo rifle shooters simply don't try higher pressure loads?

Any of you out there shooting 45-70 cast bullets with high BHN?

Jim G

 

[Charlie98]

I don't cast my own, so I'm at the mercy of whatever I get commercially. Having said that...

Are you sure you have the right size bullet for your bore? If your heavy bullet is becoming unstable at such a short distance, there is something else going wrong besides the bullet hardness.

 

[JimGnitecki]

I don't cast my own, so I'm at the mercy of whatever I get commercially. Having said that...

Are you sure you have the right size bullet for your bore? If your heavy bullet is becoming unstable at such a short distance, there is something else going wrong besides the bullet hardness.

The .460" diameter I am using in sizing my bullets is what is recommended for the Pedersoli 45-70 replica rifles. The instability of the former bullet was caused by the shape of the bullet itself, as others, some right on this forum, have verified. Transonic effects also added som issues of course as well. The new bullet seems completely stable, just not quite as accurate as the older bullet was. I did do a ladder test with the new bullet, and did select the best load from that.

There are multiple possible reasons:

- Quality of the cast bullets from a specific mold. I am TRYING to make bullets as good as I can make them, but of course getting used to a new mold and a new bullet shape takes time

- Transonic effects, since ALL the buffalo replica rifles operate in bullet velocity ranges right around the speed of sound, which is a bad place to be (which is why I am trying to at least start the bullet out with a muzzle velocity as high as I can reasonably go with a cast 45-70m bullet)

- Less than optimal loading processes, which is why I am being very careful on things like COAL, crimp, powder coat quality, etc

ONE of my current suspicions though is that changing from lower velocity / lower pressure loads in the 1050 fps to 1300 fps range and under 19,000 psi range, to this apparently notably higher 1350 fps to 1375 fps and (per the load tables) 28,000 psi peak pressure, MIGHT require higher BHN (if Richard Lee was correct), depsite the helpful effects of powder coating versus conventional lubing. THAT's the reason for asking the question: Might I actually need notably higher BHN, and might it need to be as high as BHN =22?

Richard Lee seemed to think so.

Jim G

 

[Chief TC]

Everything I have read indicates BHN of 15 or less works just fine for these rifles under 1500fps. Smokeless or BP. Bullet weight, bullet diameter and charge have much more to do with results.

 

[JimGnitecki]

Everything I have read indicates BHN of 15 or less works just fine for these rifles under 1500fps. Smokeless or BP. Bullet weight, bullet diameter and charge have much more to do with results.

But, has anyone ever actually done testing with different BHNs, in a buffalo rifle, and if so, determined that BHN =15 (or any other specific number) is OPTIMAL? (i.e going harder did not improve accuracy?). I'm asking because most shooters recognize barrel leading as an indicator to go to a higher BHN, but has anyone other than Richard Lee actually tested BHN effects on ACCURACY?

Jim G

 

[Chief TC]

But, has anyone ever actually done testing with different BHNs, in a buffalo rifle, and if so, determined that BHN =15 (or any other specific number) is OPTIMAL? (i.e going harder did not improve accuracy?). I'm asking because most shooters recognize barrel leading as an indicator to go to a higher BHN, but has anyone other than Richard Lee actually tested BHN effects on ACCURACY?

Jim G

I have never read anything about a certain BHN being optimal. Leading of a barrel can occur with any BHN depending on all the factors on that particular scenario. Leading with low BHN usually has to do with too small a bullet or pushing too fast. Most competitive buffalo rifle shooters are using cast bullets 10-12 BHN based on the lead to tin ratio. I have shot loads up to 1500fps with BHN up to 13 with no problems but I do use moly coated. Might as well go jacketed beyond 1500fps IMHO. I have read that those who make sure they shoot bullets specifically in diameter accordiung to their bore should use around 12 BHN but use 10 if the bullet is smaller and the softness will help it obturate properly.

 

[Hooda Thunkit]

You are asking a general question about a specific rifle.

You want to know if a harder alloy will shoot better in your rifle, and the only person who can answer that is the person shooting the rifle.

You.

Try it and see.

A bit less of "What will happen if I try XXX?", and bit more of "Here's what happened when I tried XXX! "


As for Richard Lee and the BnH equation; try to view that number as a suggestion not a rule.
If the equation says that it takes 22 BhN to work properly, think if it as saying that it may take UP TO 22 to work correctly. Better yet, think if it as saying that anything UNDER 22 may work correctly.

In my experience, I am shooting MUCH softer bullets than what the equation calls for.

When those black powder cartridge rifles (or even muzzle stuffers) they were shooting mostly pure soft lead. At the most, they were using a tin alloy, somewhere around 20-1, but often much softer.

Lastly ; don't get too hung up on exact numbers. It's not all that science - just try shooting it. And keep notes.

 

[JimGnitecki]

I will load up 50 cartridges using the BHN 12.5 alloy and see if it performs any differently than the BHN = 10. Then I will try a higher BHN, maybe 15 or 18. With the 3 data points of BHN 10, 12.5 and 15 or 18, I'll see if there is any accuracy difference, and if so, how much.

Jim G

 

[ballman6711]

The .460" diameter I am using in sizing my bullets is what is recommended for the Pedersoli 45-70 replica rifles.

Your rifle may not perform best with what is recommended. I would slug the barrel and then size my bullets .001/.002" larger.

Next I would play with powder charge and bullet hardness.

FWIW I don't cast my own bullets, but I do shoot both lubed and coated bullets in my pistols and get great accuracy when I do my part.

Kudos to you for shooting a buffalo rifle at the distances you're shooting at, and I sincerely hope you get it sorted.

chris

 

[Charlie98]

The .460" diameter I am using in sizing my bullets is what is recommended for the Pedersoli 45-70 replica rifles. The instability of the former bullet was caused by the shape of the bullet itself, as others, some right on this forum, have verified. Transonic effects also added som issues of course as well. The new bullet seems completely stable, just not quite as accurate as the older bullet was. I did do a ladder test with the new bullet, and did select the best load from that.

You have a lot going on here.

First... I have a Pedersoli 1885, and I shoot .459" commercially cast bullets with good results. My general threshold is 1500fps and below, so you and I are trying to do the same basic thing.... except... I don't go below 1300fps. The bullet has to get moving to stay in motion... and that is the redeeming quality of those heavy bullets. You might be correct... maybe you are dancing around the transonic area too much. I've thrown my 405grn bullets out past 700yds without issues. I would suspect your rifling twist, and mine, would be the same... but that is something to check, also.

The other thing is bullet obturation. You didn't note your powder and charge weight, and I don't recall from your past posts what you are using. You might need to kick that bullet in the base a little harder, and/or you might need more diameter. .460" sounds like a lot... but have you slugged your bore?

 

[Chief TC]

Bottomline is you have to try lots of things to see what works best and only change 1 factor at a time. Every BP shooter I have talked to all say how frustrating it was to determine the best load. And the smokeless guys expereince the same thing but determining best load usually goes a little faster. You are using cast bullets with smokeless in a buffalo gun - it is going to take a little bit to get it all sorted out. Don't chase any particular advice or thought. Everyone and everything is unique. For me, moly coated bullets work great. I dont use wads in my TD but I use them in my Pedersoli Sharps. I don't drop tube BP, I can us large pistol primers and .460 dia works best in both my 45-70 rifles. That is what I have learned and took awhile to figure out. Since I have a Pedersoli Sharps and shot lots of different loads through it, I don't believe a harder BHN for loads under 1500fps will matter in terms of accuracy.

 

[AJC1]

My 12 bhn bullets pc just like yours are good to 35psi that I have loaded. Elmer Keith used 12 and just went nuts blowing up guns at 50-60kpsi. You can bet your last looney that 12 is all that is needed.

 

[JimGnitecki]

You have a lot going on here.

First... I have a Pedersoli 1885, and I shoot .459" commercially cast bullets with good results. My general threshold is 1500fps and below, so you and I are trying to do the same basic thing.... except... I don't go below 1300fps. The bullet has to get moving to stay in motion... and that is the redeeming quality of those heavy bullets. You might be correct... maybe you are dancing around the transonic area too much. I've thrown my 405grn bullets out past 700yds without issues. I would suspect your rifling twist, and mine, would be the same... but that is something to check, also.

The other thing is bullet obturation. You didn't note your powder and charge weight, and I don't recall from your past posts what you are using. You might need to kick that bullet in the base a little harder, and/or you might need more diameter. .460" sounds like a lot... but have you slugged your bore?

Thanks for the detailed analysis! My rifle twist is 1:18. My bets load so far is Accurate 5744, 27.5g, and it pushes the bullet out of the muzzle (per Labradar) at 1355 to 1375 depending upon anbient temperature and rifle temperature. The load table limit for 5744 with a 500g bullet is 28g at suppsoedly 28,000 psi. In ladder testing, the rifle shot most accurately at 27.5g. At 28g, the accuracy was repeatedly not as good. So, I cnanot get the bullet going any faster.

The BC, per online formulas based upon comparing Labradar velocity at 2 different ranges, is 0.42. That is almost exactly what Lee claims for this bullet, so I trust it is accurate.

I powder coat this bullet and then size it to .460", as my barrel has been slugged by a gunsmith and he says it is .4563".

Even with that great 0.42 BC, it is impossible for me to avoid the transonic zone, which as you likely know, extends both above and below the actual speed of sound with effects being typically noted as low as under 1000 fps and and as high as 1250 or even more, depending upon specific bullet shape.

Also, something weird seems to happen with both the last bulelt I tried (the 485g Lee sharp ogive shape) and the current 500g Lee 459 500 3R bullet, a graph of velocity versus distance goes crazy at some point. With the old bullet it was at around 150 yards, and with the new bullet, it was at around 200 yards. Here is the graph for the new bullet:




We both know that bullets cannot actually stay at the same velocity, or actually INcrease velocity, while flying at high speed through the air. The velocity must always decrease due to air resistance. But the Labradar produces this result CONSISTENTLY. is this some weird transonic effect deceiving the Labradar?

By the way, the reason the Labradar can pick up this bullet's velocity even at such longer than typical Labradar distances, is because the bullet diameter is so large.

Jim G

 

[Chief TC]

You keep mentioning it slugged at .456. If so, and measured correctly, .460 is most likely too big. Usually, .001 to .002 is the right size to be above the slug measurement. So you really should be at .458 and .459 at the most. Mine slugged at .4585 and .460 is the ticket. Most Pedersolis seem to like .460 but that is because they are .458 - .459. This is specifically with cast bullets. If I use hardcast bullets that are only .458 - they keyhole. When you say .456, are you referring to groove or bore diameter?

 

[LV Gun]

I had great accuracy with a specific Lee bullet mold and a Lead alloy with BHN = 10, in my Pedersoli Sharps .45-70 replica, shooting a 485g bullet when shooting at 100 yards. But, that bullet design became unstable enough by 150 meters = 164 yards that it would not group at all.

With the new slightly heavier bullet mold I am using now (497g and very slightly different ogive), versus the older mold, the bullets are stable now at ranges beyond 100 yards. The new bullets do group well at 164 yards, but not PROPORTIONATELY as well as the older bullets did at 100 yards. i.e. Accuracy is inferior on the new bullets on an MOA basis.

The bullet alloy I have been using is wheel weight based, with 1% more Tin added, resulting in that BHN = 10, which is a relatively soft bullet. I had used the BHN = 10 alloy successfully at 100 yards with loads whose peak pressure was 19,000 psi or lower. But now, I have realized that avoiding transonic bullet velocity ranges is more important than I knew, and have stepped up velocity to a 1350 to 1375 fps range, and that velocity range is supposedly (per load tables) generating peak pressures as high as 28,000 psi.

I ran out of wheel weights, and so have switched to using an alloy, made from pure Lead, Rotometals Super Hard ingot, and pure Tin. I mixed these to generate an alloy whose BHN = 12.5. I want to see if the BHN = 12.5 will improve the accuracy. Since I am powder coating versus using conventional lubricants, I have not been getting any barrel leading at all with BHN = 10. But, Richard Lee devoted an entire chapter in "Modern Reloading" to how BHN is important in optimizing accuracy, and how bullet BHN should be "matched" to peak pressure, with peak pressure being about 90% of bullet strength.

View attachment 1176551

On that basis, the BHN =10 alloy I have been using is "way too soft", even though my use of powder coating versus conventional lubrication gives me a lot more leeway on bullet hardness.

But if Richard Lee was correct in his stance, then BHN = 12.5 is still not going to be enough of an increase in hardness given the load that I am using now. The Richard Lee data in Modern Reloading seems to indicate that a BHN as high as 22 might be ideal.

Since I already have made a small test batch of bullets using the BHN = 12.5 alloy, I am planning to do some range testing to see if accuracy remains the same or gets better. If it gets better, which the Richard Lee experimentation predicts it will, I will next test an even higher BHN alloy, and work my way upward.

But, I have consistently read on online forums that most of the 45-70 replica "buffalo rifles", and Pedersoli rifles specifically, normally do not require BHNs anywhere near that high. Is this because most buffalo rifles are being shot at lower velocities with low peak pressures (much lower than the 28,000 psi the load tables say I am at when shooting a 500g bullet at 1350 to 1375 fps)? Or, is it because conventional cast bullet lubricants simply don't work well at 1400 fps velocities and so buffalo rifle shooters simply don't try higher pressure loads?

Any of you out there shooting 45-70 cast bullets with high BHN?

Jim G

Jim, I shoot 45/70 but not in a rifle I have a Magnum Research BFR 5 shot revolver I use only lead bullets from Rim Rock Bullet Co. or from Missouri Bullets which I get through Grafs I use a .459 diameter bullet 300 grain with 38.7 grains of IMR 3031and a LRM primer . I slugged my barrel which helped a lot that is how I got to a .459 bullet. It is just crazy accurate with a .459 bullet don’t know if this will help but I wanted to share my journey with you I do however feel that.460 is too large I would slug the barrel.

 

[Blue68f100]

My take on this is the Lab Radar is picking up the transonic zone and giving you a ERROR reading. There is no way it's going to increase in speed. May report this to Lab Radar, it may be a bug in there firmware/software.

 

[JimGnitecki]

You keep mentioning it slugged at .456. If so, and measured correctly, .460 is most likely too big. Usually, .001 to .002 is the right size to be above the slug measurement. So you really should be at .458 and .459 at the most. Mine slugged at .4585 and .460 is the ticket. Most Pedersolis seem to like .460 but that is because they are .458 - .459. This is specifically with cast bullets. If I use hardcast bullets that are only .458 - they keyhole. When you say .456, are you referring to groove or bore diameter?

The .4563" was apparently groove diameter. I do have a .459" sizer insert that I can try. IF the .460" is really "too tight", what would the symptoms be?

Jim G

 

[JimGnitecki]

My take on this is the Lab Radar is picking up the transonic zone and giving you a ERROR reading. There is no way it's going to increase in speed. May report this to Lab Radar, it may be a bug in there firmware/software.

You are right that I should probably report the data to Labradar. It would be interesting to see what they say.

Jim G

 

[Charlie98]

Labradar is Doppler, correct? I'mma guess the the vapor trail behind the bullet is freaking the reader out. Doppler is good, but it's not infallible... it may actually be reading the noise behind the bullet.

I would agree with the others... I would size a few to .459" and give it a go. FWIW, I wouldn't think you would even need to PC those bullets... a good lube would work fine at those velocities.

You might also try another powder. I know you have supply issues up yonder, but IMR or H4198, Reloder 7, or even IMR3031 might be worth a try. Shooters World Buffalo Rifle, which is actually the old AA5744 powder.

 

[Chief TC]

The .4563" was apparently groove diameter. I do have a .459" sizer insert that I can try. IF the .460" is really "too tight", what would the symptoms be?

Jim G

Too big a bullet tends to just not group well as the correct sized bullet and also big fliers.

 

[JimGnitecki]

Too big a bullet tends to just not group well as the correct sized bullet and also big fliers.

As I pointed out earlier in the thread, I WAS getting flyers, and the group size are still larger than I think they could and should be,

In addition, I have sometimes been experiencing 1 or 2, and once even 3, cartridges within a box of 40 or 50 cartridges, which wouldn't chamber. Upon careful examination and disassembly of those cartridges, case length, COAL, Base-to-ogive, expander setting, and crimp setting, were all consistent with the other cartridges in the box. I had assumed that I just have a chamber that is on the tight side of the tolerances. Maybe the .460" sizing is causing a few of the cast bullets to hang up in the throat?

So yes, I'll try the .459" sizer insert, even though that will also necessitate redoing the expander setting and the crimp setting which took a while to get "perfect" (bullets slide into the flared case avoiding either abrasion or looseness, and the crimp merely removes the flare and ensures consistency of the case grip on the bullet).

Jim G

 

[Chief TC]

As I pointed out earlier in the thread, I WAS getting flyers, and the group size are still larger than I think they could and should be,

In addition, I have sometimes been experiencing 1 or 2, and once even 3, cartridges within a box of 40 or 50 cartridges, which wouldn't chamber. Upon careful examination and disassembly of those cartridges, case length, COAL, Base-to-ogive, expander setting, and crimp setting, were all consistent with the other cartridges in the box. I had assumed that I just have a chamber that is on the tight side of the tolerances. Maybe the .460" sizing is causing a few of the cast bullets to hang up in the throat?

So yes, I'll try the .459" sizer insert, even though that will also necessitate redoing the expander setting and the crimp setting which took a while to get "perfect" (bullets slide into the flared case avoiding either abrasion or looseness, and the crimp merely removes the flare and ensures consistency of the case grip on the bullet).

Jim G

Definitely try .459 and .458, see which one performs best and stick with your BHN.

 

[Bronco72]

The right size is very important! However if you decide to change the BHN, I have some other input I would like to share!

I do not cast for 45-70, yet ! BUT I do cast for other calibers, try water quenching first to raise BHN instead of changing alloy ! That alone will raise you BHN 5 to 7 points alone. Takes about 24 to 48 hours to fully harden. I have a bucket with a bunch of 3" cubed sponges on top of the water than I drop from mold about 1 foot above the water, so they don't hit bottom right away. When casting 535 grain bullets for my 50-110 they hit the bottom through about 10' of water and still dent sometime, still soft, without the sponges. I have a Magma Engineering sizer and luber and found that if I wait a day or two it is a lot harder to push them through than if I do them within 10 to 12 hours after casting.

Good luck and please let us know what you discover

John

 

[JimGnitecki]

I had already made a batch of cartridges with .460" diameter bullets and alloy that is BHN = 12.5. I will test that at my next range seesion, as my first test to see if BHN 12.5 versus BHN 10 makes any difference.

But, I just cast just over 100 bullets this morning using an alloy formula that is supposed to yield BHN = 15. I will use up 50 of them for my second test:
- I will size half of the bullets to .460" (so the only change is the change from BHN 10 to BHN 15)
- I will size half of the bullets to .459" (so those cartridges will have BOTH the harder BHN 15 alloy AND the smaller .459" diameter.

I also discovered something interesting about Lee molds that I do not recall their mold maintenance instructions mentioning:

The sprue plate was getting a bit loose, so I wanted to tighten the screw that it hinges on. But, when I used a screwdrvier to do so, it got looser! So i figured out that it has a LEFTHAND thread!

This makes sense, because the sprue plate on the Lee 459 500 3R mold rotates leftward. Giving the hinge screw a lefthand thread therefor prevents the screw from unthreading as you strike the sprue plate leftward when using the mold.

I do keep that screw, and both of the mold pins properly lubricated with Bees Wax. The Bees Wax on the screw spreads to the underside of the sprue plate, and so minimizes the striking force needed to open the sprue plate. Apparently, NOT lubricating the bolt eventually causes the sprue plate to gall the aluminum mold halves, which effectively destroys the mold. Lee is not kidding though when they say to melt just a very small drop of Bees Wax onto that bolt. The Bees Wax spreads out thin and fast.

Unfortunately, our local weather is suddenly taking a wintry turn, with the next few days forecast calling for rain, snow, and daily HIGHs as low as +2C = 4F. So, the next range session might not occur for several days.

Jim G

 

[JimGnitecki]

I used the Labradar website "Contact Us" feature to describe the weird INcreasing velocity readings I am getting past 200 yards, and asked them how and why these might being created. It's Sunday, so I don't expect an answer for at least a couple of days.

Jim G