Lyman 457132

[Kurt]

I watched that video John and the way that guy was plastering that iron the 671 might be one worth looking into.
I don't know about that 46-436 V it might be a good one for the 95 Marlin but there would be a couple changes I would make from the way it is drawn up for the slow twist my Marlin has.

[SgtDog0311]

Kurt, on the 46-436 -- a good example of a guy embarking on a new path, wanting a high BC then confining himself to Tom's limitation of "no round points". Just my opinion but leaves him straining between two worlds. I'll get to meet the gentlemen as I think he plans to spend a week there with us this summer. Its all fun, and especially when people show up who have never shot past 200yds. Grinning is contagious!

[SgtDog0311]

Guess the easy thing is to ask Bob about that Sharps bullet mold. Seemed like you mentioned a Sharps 'nose' over on the Shiloh forum is why I thought to ask you Kurt about that one.

Was surprised I didn't find a TNT drawing of the 457671 but I did for the other two. These are early versions of the software evidently since the legend is slightly different. The 'Center of Gravity' and 'Center of Pressure' are shown different nowadays.

I like that legend-information as much as the drawing. Appreciate the "Form Factor", balance between THOSE TWO CENTERS being one of it's components. Appreciate seeing the radius for the nose too. And I even appreciate the Lube Capacity. The BC gets scrutiny but it's a benchmark and I wouldn't bet against Tom Myers' calculations. Whatever you think about BC it can be useful for apples-to-apples comparisons.
       


Guess I'll have to draw the 457167 and the Sharps bullet from Scratch. Makes you really appreciate someone who will go to the trouble of sending a perfect stranger a bullet from his rare mold!

[Kurt]

John I have not seen sharps grooved bullets or loaded rounds with a grooved bullet, yes they used them but I have never seen one other then just a drawing of them. Ballard and Maynard were common with grooved bullets and some looked like the drawing of the 436 that Tom made but with more grooves. All of the original Sharps bullets I have seen and I had duplicated have a ogive similar to the grooved #2 bullet in your picture and what I use.

One of the things I would change on the 436 bullet is shorten up the ogive, I feel that it's to long for the shank mainly for a slow ROT. That is the reason a faster twist is a better option for the long money bullet noses. For a 18 ROT I don't like a ogive as long as the base.
That 436 might be fine for a smokeless load that gets pushed faster then a BP load can.

Looking at the dimensions of the 121 bullet even with the low BC estimated I can see why it shoots so well even at long range.
I would keep the nose of that 436 the same as the 121.

[SgtDog0311]

Thanks Kurt. "For a 18 ROT I don't like a ogive as long as the base". Good reminder for me to keep in mind. Think I've read where you said that before!

[bruce moulds]

sgtdog,
while that software is interesting, it oversimplifies some things.
one example is how it shows the centre of pressure.
the centre of pressure actually shifts, as in supersonic flight it is in one spot, transonic forward of that, and subsonic a little back from there.
another thing it does is assume the bullet remains the same shape as when cast, which is not the case.
the main value of the software is to present a drawing of the bullet you want to a mould maker.
keep safe,
bruce.

[bruce moulds]

looking at the drawings of 121 and 132 shows a thing that was bad for some and good for others.
probably on 121 it was not a negative due to the short nose, but some had problems with the 132.
in front of the front driving band the diameter of both bullets is 0.445", and the 132 tapers to 0.440".
this is loose in a 0.450 bore, and fits as it does when the nose sets back.
softer alloy will drive it into the rifling with more emphasis than a harder alloy.
such a nose can set back off centre, causing poor accuracy.
the plus side of that measurement is that the bullets will chamber more easily in dirty throats.
kind of a double edged sword so to speak.
those who got good results with the original postell swore by it, and those that could not master it swore at it.
if it can be got to shoot, the added bonus is that it has firther to set back before it presses hard into the riflin and causes leading like the paul jones creedmoor with its long bore ride section.
the postell, and possibly the other bullet, were designed in the day, so maybe we can learn something here.
keep safe,
bruce.

[SgtDog0311]

Bruce, That is a valid point about the dynamic nature of flight/velocity and how that complicates any given stat. But it's a starting point and not sure how Tom or anyone would provide calculations to give a complete picture for the duration of a bullet's flight. Before his software calculates "stability" it DOES ask for velocity. Now, at a given velocity, does it calculate duration at speeds? I'd have to ask Tom that question.

As for BC and the change in shape after ignition, I reckon we'd have to say the same for all bullets that are not hard cast, unless shot with Smokeless, which accomplishes nothing near BP obturation. That is why I say its just an apples-to-apples comparison. Bullet 'A' drawn with the software compared to bullet 'B' drawn and calculated with the same software, so to speak.

But as you say, one of the biggest advantages is the ability to relay exact expectations to the mold maker. Another is this... I can pull a drawing up that I've made or one I like that is in the database and make any change anywhere on the bullet and then view the result immediately, allowing me to continue the process till I'm content with the result. Time consuming it is, but something I prefer before buying a mold unless it's an offering I'm after that exists on someone's page such as BACO.

Tom is not a spring chicken so what's to become of the software once he no longer maintains it? I know several mold makers use his software and I'm told that one (who we all respect here on the forums) may be taking over care and feeding. The question there will be is it for their own purposes or will they continue to market it.

On another note... I got my bullets from old-win yesterday and doggon do I like that PJ Sharps bullet about as much as the Original Ideal Postell. I reckon my end-state will be two molds... a variation of one of those two as well as a variation of the 121.

Regarding your and other comments on the Postell undersized nose profile or base of that nose in front of the first driving band... I have this question. I'll caveat the question with this: I have Creedmoor for my 40 caliber and I think the bore riding section is .250 long; I've always wondered about moderate leading is a result of the longer bore riding section. So my question would be this... wanting good alignment I had thought to modify either the driving band and possibly even a very short section of the nose base to be very near the bore diameter. But reading your comments, as well as having the moderate leading with the Creedmoor, I'm wondering would I be inviting the same problem?? So far with blowtubing, and with OE, I have not had problems chambering during the length of a BPCR match but I'd be interested in opinions -- that is if I've been clear enough here.

[SgtDog0311]

This is not the 132 (subject of this thread) but rather a modified version of the 121 with some of the changes I'd thought to play with. From my Creedmoor experience with chambering/Blowtubing I would not anticipate a problem. Anyway, just a dry run of an initial change.

Could be a little short for an 18 twist I suppose but if Kurt and others have had no issue with the original Lyman don't see why you would with this length (ever so slightly longer).
   

Radius is very nearly exact to the original.
Nose (less the first driving band) is close to caliber diameter.
Lube grooves are shallower and volume could be increased by deeper grooves but keeping what Kurt said in mind there.
Base band is beefier, which I wanted.
Centers are within 2% of each other. BC and Form Factor slightly improved and weight increased to 455gr.
First driving band is bore diameter and base of nose is a couple thousands under.
Could possibly seat with one lube groove showing but I have not done a chamber cast yet (no cerrosafe at the moment).

[Hiwall55]

Looks like a good hunting bullet, Bill.