Bullet balance

[Blackwater]

Well, every time I think I'm settled on a design at Mountain Mould's website, something else comes up to make me doubt my wisdom. I want a 535 gr. bore rider for my BPCR. I've been warned already that a bore rider may not be the best way to go, but I'm hell bent on it because it's the only way I see to get the powder capacity I want, AND (maybe? hoperully?) get the maximum amount of "bullet guidance" via contact with the lands if not the grooves.

My design thus far is for .725" nose length, .460" base dia. & .450" bore rider dia., 1.0 groove to band ratio, .220" bore ride length, 52% meplat, WW's (what else? I'm tired of paying for tin!). I WAS going to go with .250" bore ride length, but the bullet looked nose heavy, and going to .220" bore ride length seemed to make the drawing look better balanced, at least to my not-so-educated eye.

Can anyone comment on the likliness that the balance of the bullet would outweigh the longer bearing length, if you can call a bore riding section "bearing length?"

I love Dan's program, but really want this bullet to work in my Browning 1885 BPCR in .45/70, and all I have, really, to go by is my Mark I micrometer eyeball, which has been known to jump a cog now and then. Any help/advice you guys can give me would be appreciated.

Looks to me like the shorter bore ride length, which makes for a longer nose (though unsupported, of course) makes a more balanced looking bullet. Am I full of it here, or not???

[Bullshop]

Why dont you have him cut it with the DD ring like Walt Melander used to do. That way you can have the long bore ride nose with support at both ends.
BIC/BS

[Bass Ackward]

My only comments will involve the bore ride design itself. Bearing length is that portion of the bullet that fills the grooves and contributes to drive rotation of the bullet. The smaller this distance is made on a heavy for caliber bullet, the harder (BHN) the bullet will need to be compared to what a full diameter design will offer at the same velocity.

So your problem is balancing your need for case capacity to reach the velocity level you desire with your bullet design's ability to handle it. You can usually get away with this more in the smaller calibers because the inertia isn't there with bullet weight fighting .004 tall rifling.

So my advice would be to look at several designs that have stood the test of time and design one with a bore ride section slightly shorter than the average of those that are of a bore ride design. That's the only way "I know" to be .... safe that what you buy will fly like you want it to.

My way of dealing with this would be to CHEAT. I would rent a throater reamer for about $20 and create the throat of my dreams. Then design a "real" bullet to fit it after firing a few jacketed to smooth it up.

[JDL]

Blackwater,
This is interesting as just last week I contacted Dan with a question about front band length for my Browning B-78 .45-70. He was surprised with the throat dimentions of my rifle and said most .45-70's just had a large funnel type throat. I was wondering what your rifle's throat measured and if the Brownings' were boared differently from most?-JDL

[powderburnerr]

i have found that the 45-70s made by most BP outfits seem to have a throat in them if you want to try a borerider .drop me a e-mail and I can send you a copy or two ,lyman makes a 500 gn that shoots very well in the 45-70 and they have a discontinued 560 that shoots real well . it doesnt shoot tiny grups but does shoot consistantly to 1000 yds,the three front bands are tapered . it was the first bullet I got to shoot good in a 45- 110 . if they do what you want them to do then you can send the measurements to MM....Dean

[Nazgul]

I have a Browning BPCR in 45-70. The Lyman 500gr round nose fits very well with plain WW material. I have tried 13 separate moulds from all the major manufacturers and one custom. The Lyman RN outshoots them all. Having said that I have not had the chance to design and shoot one from MM. I keep coming back to the Lyman as the most accurate I have tried. Do not as yet compete with the gun but have shot it for 7 years at my own range and get 4" 300 yard groups when I am doing things right.

It is far more fun than I should be allowed to have.

[Blackwater]

Thanks for the comments, guys. I can't remember the exact measurements of the throat, but it's very close and tight. The gun has a Badger barrel, and the chamber is designed with that close, tight chamber specifically for cast bullets and match grade accuracy. My only throat consideration is adjusting my OAL to get just the right amount of contact as I close the lever. The gun has a few thou of "leverage" as it's closed, so I can get good contact, where that becomes a factor with a load.

Bass, thanks for your input. I've thoght of lengthening that throat, but then my other moulds wouldn't fit right, so I don't really think that's a very practical solution for me, BUT, your comments and experience are ALWAYS very salient and appreciated. Essentially, that's what my problem is, and I want my Mtn. Mould to fit the gun as is, give me the capacity I need, and bullet length/wt. I want, so a bore rider looks to be the only viable compromise I can come up with. I do think I'm going to push the envelope with the nose diameter. I can always adjust the alloy specifically for that bullet so it rides the lands as tightly as possible.

I've seen some photos of recovered bullets that show softer bullets being "bumped up" on the bore riding section also, so my thinking is that if the bore riding section keeps the bullet aligned well, that bumping up MAY (??? - we'll see I guess) just let a longer bullet be loaded out longer to get the capacity I need, and then just fill the grooves on that more sudden ignition that BP is noted for. That's my thinking, anyway, and of course it's just a theory that will require getting the mould to prove or disprove.

Any comment on how "reliable" the visual impression of the "balance" of a given bullet may be for determining its eventual accuracy? DARN! This bullet designing stuff CAN get a bit confusing, can't it? Mostly, I'm just going on instinct, and I guess that'll wind up being the final factor in guessing what I'll order. I DO want to make as sure as possible that I've touched all the bases before ordering, and that's the reason for my quesiton. Too much knowledge and experience here for me NOT to ask!

[Blackwater]

Before I leave this subject lay, I gotta' ask one more question. By "bullet balance," I THINK (?) I'm referring to the bullet's natural physical balancing point. In other words, the larger full diameter shank of the bullet has grooves in it, that lighten it from what it would be as a full cylinder. The forward portion has the nose, ojive and point that are reduced in diameter from a straight cylinder as well.

What I THINK (?) balance refers to, at least as I'm using the term here, is the literal dynamic balance point of the bullet, just as you'd refer to the balance of a fine SxS bird gun, which generally will balance on the hinge, or just slightly forward of it.

Somewhere along the line, I think it was Sierra or an article that mentioned them, stated that the most accurate J-bullets for target work had a balance point as far back from the point as possible. This helped long range accuracy, alegedly by letting the rear of the bullet "steer" it better through the tremendous resistance that air and atmosphere places upon it in its flight.

Seems to me this would be a pretty important factor in designing a bullet for a BPCR, where the bullets typically go through the much less stable transonic stage not far from the muzzle. It's this transition through the transonic stage of flight that muddles up accuracy sometimes, and the better bullet designs tend to simply get through this stage with more grace and stability than the also-rans. The Creedmoor and Postells are two examples of this, I think, and their performance in this important transonic range is alegedly one of the primary things that has given them their place of honor in long range shooting.

Seems to me the longer the ojive, the further to the rear the balance will be moved. Of course, this ALSO leaves more potential bearing surface unsupported, and alignment is probably THE most critical factor in accuracy in all loads. This means that there's a compromise between the two that must be struck, of course, which is the usual way things like this work. More of one = less of the other.

As I keep looking at the diagrams in Dan's site, trying to work out the design for "The Perfect Bullet" (yeah, I'm deep into vain endeavors), I keep noting that I CAN get more of a Postell/Creedmoor look to the bullet, and just visually, a better "balanced look" when I use a slightly shorter bore riding segment and a smaller ojive. I keep watching the diagrams, trying to take my best guess as to where I want to draw these lines, and I keep thinking that with the Postells and Creedmoors so thoroughly proven, that I do need to emulate them a bit more than I'd planned at first.

I want this bullet to fly right, and to do it out at long range, so this is why I'm inquiring about "bullet balance." I've been around these things long enough to know that there is often things I don't know, that I'm not aware that I don't know, and I hate to go through all the time and trouble of working up a load without getting the design as close to what I want as possible, balancing out all factors as best as I can at this point. It just looks to me like I've got one last round of re-thinking before I order this mould, and anyone who can or cares to comment on balancing these things out please feel free to do so.

Right now, I'm lengthening the nose a tad, and the ojive. I've still got @ 70% "bearing surface" according to Dan's calculations, but of course that all depends on alloying up and casting at the right temp so that the bore riding section actually DOES ride the bore. I'm flirting with getting the specs a smidge TOO tight, maybe, but I know that's my risk. Like the guy in Dirty Harry, "I gots ta' know."

Besides, looking at the 311291 and many others that have stood the test of time and performed well across the board, I see their balance seems to be at least somewhat similar, and their designs not as different as I'd thought at first glance. I think Bass's (or whoever it was?) comments some time back about going to smaller meplats so the bullets would range better are finally turning on a light in my head ... finally. Seems this would affect the bullet's balance more than any other factor, and maybe that's the reason the smaller meplats perform well upon a broader range of applications?

Just thought this was something that merited some discussion, and maybe that I'd glean yet another pearl from the more knowledgeable and experienced in this realm.

[felix]

Blackwater, you are doing good. Just remember that in outer space a full wadcutter is the way to go. Whenever you have resistance, you need a sharp point to plow through the medium, and the twist necessary to keep that point going straight on. Less weight up front requires more twist, and that is the downfall of OUR lead projectiles. ... felix

[Blackwater]

Yeah, that makes a lot of sense. Of course, I think I'm STILL left with just looking at the graphic of the design, and personal intuition as to what looks "balanced" and the "best" compromise of all the pertinent factors. No way to get around that guessing, is there?

At least I've got some good pics in my mind of the designs we KNOW work, so .... maybe that'll help. I really ought to go with a bullet for the .44 pistol first, I guess, but that wouldn't teach me a thing about the BPCR, would it? So then I'd be left STILL not knowing, and the only way to KNOW is to get the dang mould and shoot it to see. I think I'm just going to go with my instincts, and I'm sure I'll get another for the gun with a big flat meplat for hunting anyway. Sure would be nice to take an elk or bison or something with that gun some day. Come to think of it, a sweet little whitetail doe wouldn't be a BAD thing, either, would it?

Sometimes I think it's all this angst leading up to the final decision, and the risk, that makes it so darn interesting and absorbing, and makes any successes so dang sweet ... when they happen. A couple of months of saving my Coke money will pay for the single cav and top punch, so it's not the money but the work and precious TIME involved in wringing out a given bullet that makes me hesitate - well, that and the fact that something keeps nagging at me, making me think I haven't considered ALL the parameters and factors involved.

Confucious say, "Longest journey always begin with first step," so looks like I'm gonna' hafta' make up my mind and see how it works out. My Saeco 745 is doing pretty good, but can't help but think I need to try another mould. I've been pretty stubborn in wringing that one out, and it's time to broaden my perspective.

A buddy recently got a Lyman 457125, a bullet I'd really like to shoot, but the mould had BIG problems. He said it cast "square bullets," which is only a SLIGHT exaggeration, and I've heard of too darn many folks having problems with Lyman moulds recently to trust them, and this rifle seems to demand the best mould I can get for the results I want from it. His Lyman mould had pooched out on the inner face where the alignment pins were pushed in, and it would NOT throw a decent bullet no matter what. I volunteered to try to fix it, since he didn't want to send it back, and now I've got one of the pins stuck from trying to tap it back in. Peened out, I guess. Will be drilling it out with an undersize bit, to see if that'll allow me to get it out, and then will try to make a pin to fit. It's been a real PITA mould, and has kinda' turned me off Lyman moulds until I hear their QC is up to par. This mould should never have passed a simple visual inspection, and he couldn't get the noses to fit his bore, so it was useless to him, and now a big aggrevation for me, though it HAS been a bit of a learning experience. Do they use a hot/cold press fit to lock those pins in at the factory?

[Bass Ackward]

Yeah, that makes a lot of sense. Of course, I think I'm STILL left with just looking at the graphic of the design, and personal intuition as to what looks "balanced" and the "best" compromise of all the pertinent factors. No way to get around that guessing, is there?

At least I've got some good pics in my mind of the designs we KNOW work, so .... maybe that'll help. I really ought to go with a bullet for the .44 pistol first, I guess, but that wouldn't teach me a thing about the BPCR, would it? So then I'd be left STILL not knowing, and the only way to KNOW is to get the dang mould and shoot it to see.


Blackwater,

After you design the first one, you're going to design a second one anyway. How do I know? :grin:

All I will say is that when you are truely venturing into new ground and not simply copying something else, design it once a week without looking at the last designs and print them out. When you get three weeks in a row where the designs look very similar, you have found what you wanted.

[quigleysharps4570]

Go to http://www.buffaloarms.com/ and order a new Lyman #457132 535gr. Postell and the new handles. Might save wracking your brain. :D Best thing I ever did. Had a fellow on the Shiloh site steer me that way when my old one got dropped and I couldn't get it to cast decent bullets after that. Didn't even know they'd changed handle design. I was impressed. I run the pot at 870 deg. and it turns out the best bullets I've ever put out and that Postell is a proven design.

[Blackwater]

Bass, that just may be more Truth than I can handle just now! :wink: Seriously, I think I know what you're talking about. An addict can ALWAYS tell when he's about to become addicted. He just can't say "No" for the life of him, right? I keep trying to have my cake and eat it too, or more properly, trying to see how much of each I can keep. Ain't no way to have them both, so I've just got to settle on a compromise at SOME point. Have been playing with Dan's program for maybe 6 mo., and "designing" all sorts of stuff. Seems to help to quit the BPCR bullet and go to a ..30, .31, .35 and some .44's and short .45's for the Guide Gun. When I stay at one design too long, I confuse myself even further, but you're right, and I seem to be zeroing in on some parameters, even if it is a bit slow. Looking forward to having a real nice quality mould.

And Quigley, I'm darn glad you got a good mould from Lyman, and I DO know they make some good moulds, but I guess I'm a bit demanding, and more than a few folks have had problems with Lymans. Seems their QC dept. takes a nap now and then, or something? Also, I just want to try one of Dan's moulds. Everyone says they're primo, and I don't think I've ever heard anyone say anything bad about the moulds themselves, though a few have admitted their design work didn't work out quite as planned. I've used a buddy's NEI that's a real jewell to work with, and can't help but want to get the best mould I can find, and I think I'll get a good mould from Dan. My only hesitancy is my own angst in trying to settle on a design. Like someone else noted on another thread, it's just awfully satisfying to design your own bullet, and have it work out good. A buddy told me once that I'd make my own air if I could, so that'll give you a clue of why I really want to get a MM. I'll probably wind up getting that Postell, though. Have a match this March/April that I want to do good in ... hopefully ... and having a "secret bullet" would add some real spice to that, too, so .... I'm pretty well zeroed in on a MM right now, but your point IS very well taken, and if I were a bit smarter, that's likely what I'd do. Curiosity killed the cat, but at least I don't have to worry about a bad design being fatal. :wink:

[beagle]

Bullshop....Good idea. The DD bands work and the round flat nosed jobs like the 311440, 358009, 462560 and my 358315 (MFH) when sized in the regulat manner (base first) with a flat top punch tend to form a slightly expanded nose. This expansion, if done with some finese acts as a DD band and allows the bullet to be a bore rider and shoots with enhanced accuracy./beagle

.
Why dont you have him cut it with the DD ring like Walt Melander used to do. That way you can have the long bore ride nose with support at both ends.
BIC/BS

[The Nyack Kid]

I feel your pain
Dan got the Secant boolit design feature up and running .
now ive got to compare all of the differant designs that i pulled out of my aaa....ah dreamed up , and see if they look like they will work better that way .
which is the problem in the first place even if they look like they may work , you dont know till you do some shooting.
it has been my (limited ) expirance that there won't be any problems with Dans molds , if the boolit dont fly then it's most likely the design. (mine flew just fine , that one is just so ugly that im not claiming it )

[Blackwater]

Dan won't cut that "Double Dimple" thing, will he? I think (?) that's what you're talking about???

Just came up with another question. Never really understood why the balance needed to be rearward of center so the base would "drive the front end," but had a kinda' epiphany .... I think? Did a kinda' whack my head and "Wow! I could'a had a V-8" sort of thing when I realized that stories from the Civil War of minnie balls "buzzing like hornets" sorta' (to me at the moment anyway) made sense. If the base is hollow, like a Minnie ball, and would therefore lighten the base and shift the balance FORWARD, then ANY minute imperfections would make or at least allow the base to wobble and yaw, and when something wobbles and yaws at the speed of even a .58 cal. Minnie driven by a moderate charge of black, then that's just gotta' make a "buzzing" sound, doesn't it?

Therefore, the balance being toward the base helps eliminate as much of that yawing and "buzzing" as is possible, right?

The light bulb went on, but .... is it shining in the right place?

[Bass Ackward]

The light bulb went on, but .... is it shining in the right place?


Blackwater,

Boy there is an invitation there that is hard to pass up. :grin:

There are many ways to look at and thus answer your question. The more weight on the rear of the bullet, the easier it is to stabilize and the better accuracy it will maintain when it passes back through the barrier. That was the driver for Keith and his bullet. Take the weight off the nose and it shifts the balance point back. So from this statement we can make a bunch of statements and I will just point out a few.

The more weight on the rear, the slower twist rate we need to stabilize it.
The slower the velocity we can run it at accurately.
The better long range bullet it will be.

All favorable and desireable to cast operation. Help?

[Blackwater]

Yep. It did help, and believe it or not, this finally makes sense, or at least enough to satisfy an old country boy. Thanks. I think this has gone a long way toward helping me understand "bullet balance," and MAYBE (???) why some of those old BP era moulds are shaped the way they are. More particularly, why the Postell and Creedmoor are so similar. I'm emulating them more strongly on Dan's 'puter drawings now, and feel more comfortable.

There's a LOT to designing a bullet, isn't there? Sure makes me appreciate the good ones, like the Keights mentioned. Everything tends to make a lot more sense if you can just find the right question to ask. I think it was a physicist of renown who said that finding a really good question was the hard part. If you can come up with a good question, the answer's usually pretty easy.

Funny how our instincts work too, when doing something new, like designing a bullet on Dan's software. I just sensed something was missing, even though the designs I kept coming up with were really pretty good looking. I just sensed something was missing.

Thanks.

[Buckshot]

...............Blackwater, I believe it was Wm Metford who discovered (or was most vocal about it) that a slug with a hollowpoint was more accurate. This was during the 1860's when the British with their 45 cal target rifles ruled the 1000 yard ranges. The 577 Snider had an invisible hollowpoint in that once the HP was formed, lead was spun over it to cap it. It was an accuracy aid vs having anything to do with expansion.

I suppose that's why most jacketed match bullets have hollow points?

If you are going to be shooting BP in your 45-70, and the concern is whether or not you have enough drive band surface to 'grip' the rifling, remember that all the LR muzzle loaders shot bore sized slugs. There was no groove size drive bands at all. Another thing Metford proved was that any boolit upset took place only at ignition, and nowhere else down the barrel (with BP).

If you want to experiment before finalizing a design for the length of groove diameter body it would be easy to do. Assuming the land diameter was .450" you'd need a .450" size die. Merely size the slugs nose first. Roll on a caselube pad and then run the drive bands down successively deeper into the die for each succesive test batch.

To be sure, sufficient expansion does take place. My Whitworth is .451" across the flats, but .468" across the 'grooves'. Slugs sized .451" fully expand to assume the hexagonal bore form.

http://www.fototime.com/F1793D2CF2E8E7A/standard.jpg
The Saeco #745 and the Lyman Postell 9458132) on the right, lubed and then sized to .451" both shoot exceedingly well in both the Whitworth and my Rigby type match rifles. The Rigby has a 32" Green Mountain barrel with conventional .450x.458" rifling and a 18" twist. The comparatively shallow .004" grooves do a good job of gripping and spinning the upset slug.

http://www.fototime.com/79E8B23CAB84AC7/standard.jpg
The Rigby. As I understand it, most BPCR silhuette shooters have the boolit more or less just sitting atop a cardwad with the case barely even touching the boolit? In effect it's almost a breechseating proposition. Not good for hunting but fine for the range.

http://www.fototime.com/4C9F502AC298773/standard.jpg
http://www.fototime.com/F5B2831828DBFE3/standard.jpg
These are slugs I swage for the 2 match rifles. As I said, they're obviously bore diameter until upset to take the lands at ignition. Those in the top photo are 585grs (a bit too much of a good thing) and the patched ones are 540grs with a hollow point swaged in. Basicly these rifles are muzzle loading 45-90's. They do their best work (as a type) at from 75 to 95grs of powder. Velocities run up close to 1400 fps.

You may find the base fully upsetting in the throat with the nose providing all the guidance required.

.................Buckshot

[Blackwater]

Thanks a bunch Buckshot, and MAN! You have one of the Whitworths! Those are FINE rifles, and VERY interesting. Saw one this past year, and the fellow shooting it was deadly. It's a very intriguing rifle. Never handled a Gibbs before, but sure would like to. There's just SOMETHING about those old guns, isn't there? Any man who's ever aspired to be a real shooter just HAS to appreciate the guys and guns of any era that are dedicated to hitting what one aims at, and especially those dedicated mostly to targets way out yonder. Have the Pedersoli catalog, and I'd guess there are 30 rifles in it that I lust after seriously! Lusting after rifles isn't BAD, is it? :?:

That thing about the bullet's "bore riding" section filling the grooves is very well taken. I've read where even the RN's will upset so that the nose isn't nearly as long as it is when cast, too. That's why I'm stuck on a bore rider, and so I can get the powder capacity I want/need in the gun. A buddy has an NEI mould that casts a 485 gr. (20:1) bullet that's designed to be seated out some .300" longer than normal. It effectively makes a .45/70 into a short cased .45/90. The short full diameter base section is only abut .45" long, and I can actually fill a belled case up with powder and compress the whole thing well enough to seat a card wad atop and load that bullet. I think I used as much as 86 gr. of Goex 2F behind it. It shot good, but not stellar, and I'm after stellar accuracy. It takes a really good mould to drop really stellar class bullets, too, or it at least helps, and that's why I want a MM for the gun. Well, there's that and the fact that I just like designing it myself.

I haven't been able to recover any bullets yet, but that bumping up of the whole nose, when cast of suitable alloys, is to my mind one great advantage in loading and shooting real black. I don't believe any of the imitation powders ignite with the force that real black does. I try to be a purist (as though a country boy like me COULD be a purist of any sort?) but recently picked up 5 lb. of Triple 7 at Wal Mart because they had it clearance marked to $5 per lb.! I may be a dumb country boy, but at THAT PRICE? No brainer, eh? Will use it in my muzzle loader, though. Want to keep the BPCR dedicated to only black, and I think it's time to move on to another bullet. That Saeco 745 shoots good, but I'm after stellar accuracy, and don't yet have that. It's amazing how these "old" guns can shoot, isn't it? It's just a matter of doing the homework and shooting/experimenting necessary to find what the gun wants, and sadly, it's taken me a long time to get my round tuits for that.

Thanks lalrgely to you guys, I'm casting really good bullets, and a whole new world has opened up to me now as a result. Funny how this shootin' bidniss works, ain't it?

In previous designs I've "created," I think I was trying TOO hard to get that bearing surface, and if the Postells, Creedmoors and similar have a fairly long unsupported nose, and they WORK, and HAVE worked for so very long, then maybe I need to find a clue in there. That bumping up effect will almost assuredly bump up whatever bore riding section I put on it. Can't prove that long seated NEI does that, since I haven't been able to recover any in suitable shape to draw any conclusions from, but maybe I need to get a load of sand or something and try again?

This sure is an interesting pursuit, isn't it?