43-287B

[Pistolero]

Boy, you are dead right on that, fiver. There is a video out there of a head on, 50% overlap hit between
a 59 Chevy and a 2009 Chevy, and you might think the "ole heavy iron, real steel" '59 would stand up, but the
reality is that it is deadly while you would walk away from the 2009.

Gotta think how that applies to bullets, maybe too hard is not good for forcing cone
impacts.

Not just peak pressure, but rate of rise, too. Unique will have the bullet moving
smartly by the time it hits the forcing cone. I wonder if the slower powders move
it against little resistance, then hit the forcing cone before pressure is really high enoug
to push it smoothly thru. Just a theory.

Bill

 

[Pistolero]

As far as lathe turning grooves, I marvel that you can do it at all without
damaging the shank with the chuck.

Bill

 

[Ian]

Custom-bored soft jaws.

Freebullet, I could be wrong but after seeing that photo of the bullet Brad pressed halfway into the forcing cone, I don't think it's too much base pressure wiping out the grooves, it's mostly just being sized down so much and the bullet design not allowing for much metal displacement. I know Ruger runs very tight on the groove dimension and wide on the lands, lots of metal to displace if the bullets are .432+.

 

[popper]

Nose metal moves 'forward' is really being pushed 'aside' into the groove. Same with the drive band, metal moves to an area of less resistance. Under enough pressure they will melt together of break off or both. Adding Cu allows flow without fracture. Applies to 'oversized' also. I disagree with the idea that HT Sb crunches and loses hardness. The difference in 2700 fps cast in 308 is H.T. AC the same alloy gives huge groups. On the other hand, 2100 fps PB in BO - isocore H.T vs SuperHard (equivalent BHN) shot the same. Cu GC takes very little force to work harden/brittle it. Same with the barnes solids - thus the grooves. Look at a recovered Barnes and see if the lands cut or flow the metal. I need to test my 'soft' alloy sized just over bore to see if 'oversized' really makes a difference. Didn't for the BO hard/superhard tests.

 

[freebullet]

I get that... but until we see what the baseline for best accuracy & speed is for the design as cast we won't know if /what the actual gains are or the changes effect on them. One of the reasons I tend to always shoot a work up or two when I switch bullet designs.

Wonder if nose only sizing might help. Why displace the metal in the first place kinda deal....? Could size down partway then back out. If it does help....sizing the whole bullet down to that size is easy, but then will a coating allow accuracy by bring the band's back up size.

We still don't know if a charge reduction gives a better baseline. Will the bullet take less damage & accuracy improve @19-19.5......what is the current limit on the design?

Endless options is sometimes a curse.

I hope one way or another Brad finds joy with it. I'd settle for making it to the range more, reaching a goal is secondary at the moment.

 

[popper]

You can't avoid displacing metal!

 

[Brad]

https://www.docdroid.net/file/download/udfe/january-1997.pdf

Thanks to another member for this link. Tells me we are on the right path. This is an article mentioned by Dan of Mountain Moulds in a very interesting article in the Fouling Shot. He explains why he doesn't make smooth sides bullet moulds for coating.

Seems groove do more than hold lube.

Damn, is anything really new? I am up against the paradox paradox.

 

[Pistolero]

Barnes Triple Shock is a technical peg point. I have one recovered from a kudu, but
at home. IIRC, but it has been years since I looked at it, the rifling moved copper fwd and backwards, looked a bit like the
.45 SWC pic that Ian put up, little tongue sticking out into the groove. Won't be able
to access it real soon.

Bill

 

[Brad]

I have one from a zebra. The others all kept going.

Bill, I will get some photos of the lathe setup for you. Soft jaws are the cat's meow for this type of stuff.

 

[Pistolero]

OK, will likely be out of touch for a while, no telling when power will be back, or internet.

What does your Triple Shock look like in the body? I am going from a long ago memory,
when that was not the primary thing I was looking at.

I would like to see the soft jaw setup. I was making some file handles the other day, hard
not to damage the poplar dowel when turning for steel reinforcing ring and shaping it. Soft would
be better.

Bill

 

[popper]

My smooth sided moulds have a shallow groove for collecting displaced metal. I calculated the volume of displaced metal when sized by the bore. Long time ago I twisted RD 30/30 boolits till they broke - always at the L.G. H.T. & different alloys gave interesting fracture patterns. WD from the mould was interesting too. Now I oven H.T.

 

[Pistolero]

Read the Seifried Paradox Revolver article, very interesting, and definitely applicable to this situation,
IMO.

Bill

 

[freebullet]

You can't avoid displacing metal!

Well, you can, but accuracy at magnum velocity won't be your reward. It's kinda square peg round hole deal...he might be able to manipulate the size of just that area to gain a higher speed limit with the mold he currently has. The machined bullet while certainly interesting doesn't change what he can do with the mold he already owns. It tells him about the new machined bullets capability or possibly what another new mold might do. Manipulate the size is all I was sayin'.

 

[Brad]

I sent an email to Dan at Mountain Molds. He has done a fair bit of testing on similar situations. His response is below.

Hi Brad,
Interesting how your recovered bullet on your April 19 post had "lost" its grooves. It reminded me of a revolver bullet that I recovered from water, attached below. I've been busy with rifles for the past few years so I've been neglecting revolver bullets but hope to investigate this phenomena further one of these years.

I would blame my bullet's collapsed grooves on obturation except 1) if it were only obturation, the crimp groove should have suffered minimal damage. Instead the crimp groove was hammered more than the lube groove below it. 2) if it were only obturation, then it should have obturated just as much in the Marlin, but it didn't. So I'm guessing it was due to a combination of obturation on the base of the bullet plus the Seyfried Paradox effect on the nose of the bullet as it slams into the rifling.

Your design has that humongous front band -- when that front band slams into the rifling, that creates a lot of pressure on the bullet, similar to Seyfried's Paradox bullets slamming into the rifling.

As for your bullets that appeared to enter the rifling off-center, that could be due to misalignment, or it could be due to the Paradox effect slapping the bullet around. Many of my recovered revolver bullets were off-center, too.

I have some ideas on how to reduce the distortion in revolver bullets but it may be a long time before I can work on it. My smeared revolver bullet was designed 12 or so years ago and I've learned a few things since then, and would do things differently now. Basically the same strategy that I have been using in my rifle bullets.

Kudos to you for recovering bullets and posting results.

Dan

Same ammo fired from Marlin. Despite the higher velocity, there was less damage to the grooves compared to the revolver.

 

[Brad]

The photos didn't copy over from the email. Here they are.
Look at the top bullet. Notice the similar looks damage to the bullet right down to the differential collapse of the bottom groove.

I am hoping that Dan will post more about his experiences. This is getting interesting.

 

[fiver]

that squish loss of the lube grooves is exactly what I see if I smush bullets in the swage dies.
the bottom grooves going wonky isn't from misalignment it's from pressure banging at the base.
and it happens in grooves full of fluid err lube.
I'm pretty positive it is from the lube breaking down [or an air bubble] and squirting out the side.
[this would also make old Elmer correct in his lube groove pumping theory]

the nose of course has to be held in place and pressure applied to the base for this to happen.
it's interesting to note that you can feel it in the press handle.
if you slowly raise the bullet up in the die until it makes contact then apply the force you can feel them collapse as everything gets shorter and fatter.
if you dug out the lead around the grooves you'd see what happens. [the grove isn't gone it just has other lead rolled in around/over it]
only in this case,, your doing that damage and then smushing it down and making it longer and thinner right afterwards.


Dan used to live just on the other side of the mountain from me [about 50 miles away] in Marsh Valley.
but he has recently been working on shooting plain base bullets coated in enamel at high velocity.

 

[Pistolero]

I wonder if a different powder was used in the rifle loads?

 

[Brad]

I wonder if a different powder was used in the rifle loads?

I don't think it is a powder or pressure related issue. It is a matter of the bullet not having a place to put displaced lead so the bullet become misshaped.

I want to fire some with lighter loads, maybe a light charge of TG, to see what they look like after a load in the 15 K PSI range.

 

[fiver]

6grs should put you right about there.

 

[Pistolero]

It would be good to do a lower pressure load, if for nothing else, to prove (or disprove) that pressure
isn't a factor.

Bill