Bullet Nose setback not slump.

[Kenny Wasserburger]

A previous post on nose slump was a good share of information. I didn’t wish to dilute that thread, so have waited.

I think, though nose setback is probably the more pertinent Issue to our game, than a slumping issues.

This was very much on the mind of Dan Theodor at the time of his passing. We had discussed this several times in person, Dan’s theory was the idea of compression strength of various lead tin alloys.

We all know that our bullets shorten upon firing. Just to what degree, does Alloy have effect upon this setback?

We had discussed the use of a large hydraulic press to crush the bullets and record the exact pressure required of each alloy. Where the bullet set back. This came about after we both had watched a documentary on the compressive strength of mud bricks used in construction of various things in ancient Egypt, discussions on the Bible talking about pharaoh taking away the straw.

Funny part is bricks with straw had more compressive strength than those without.

Ok enough of a back story.

I live in Gillette where we have machine shops involved in heavy oil and mining industries. One shop in particular is L&H. They have some very highly specialized presses.

I propose to contact then and see if I can get some time with one of these presses. I had volunteered this to Dan.

What I need is sample alloys, commonly used by us in BPTRA and BPCR, I need 5-8 bullets of various alloys, for the test. Multiple samples of the same alloy, will be fine.

I know Ian is going harder, and so are others.

I would like 30-1 as it was a often used alloy, maybe still is for some.
Also 20-1, 25-1, 20-1, 18-1, and 16-1, also any others, plus even those with Antimony alloys, Mike Rix.

If you want to be a part of the test please Send test samples to: Also please clearly label as to alloy composition.

Kenny Wasserburger
817 Glacier Drive
Gillette, WY 82718

PS I would give all the Data to Brent Danielson, to put up in a spreadsheet, I apologize for not asking in Advance Brent, but thought this would appeal to your own questions.

Kenny Wasserburger

[bruce m]

Kenny, you raise a good point regarding the difference between setback and slump.
in my own mind I have thought of setback as slump in a straight line, but looking at the two as different entities makes more sense.
I can say that reducing setback shows improved trajectories which translate into reduced wind deflection.
this is simply due to reducing velocity loss by having reduced drag.
an unknown is whether there is a difference in setback behaviour between pressing and banging a bullet(base).
hitting things with a hammer might well have a different reaction to squeezing them?
this could be particularly so with pencil shaped things of different lengths.
bullets have a thing called fineness ratio which is length divided by diameter, and this could well come into play when you bang one in the back.
always questions ongoing.
bruce.

[Kurt]

This subject has been an interest with me since I was a kid.
There is a great difference between slump and obturation setback. In all of my life I have only seen two bullets that I call slump. What I interpret as slump is when I see a bent ogive with land cuts farther up on one side of the ogive then the other. I have just reclaimed one five gallon and a part of a three gallon bucket full of snow bank bullets
From what I have seen with setback it can be as much as over .130" and always the land cuts are the same hight on the ogive and this tells me that the bullet will get more drag but also loose trajectory.
Dan and I had a lot of discussions through the PM's and on forum posts and a few got a little heated up when I disagreed with him and I sent him samples of some of my findings because he did not have a good media to recover bullets undamaged.
But Kenny I for one will be very interested in your findings. Keep running results of your findings.......Kurt


Here are some examples what bullet slump looks like with alloys from 1/40 to 1/16 using the mini GG money bullet out of the same mould. The far left is unfired and looking down the line you can see the different amounts of setback. I feel 1/16 is just about perfect with most loads and calibers.

IMG_1489.jpeg

[Kenny Wasserburger]

Kurt,

We both discussed the problems with firing the bullets into media. It would undoubtedly give bias to any test. As one can’t guarantee the same consistency of any media.

Hence the reason to use a measurable device.

Kenny.

[Orville]

I would suggest using a cylinder of the different alloys so the contact points in the press is always the same. A Corbin core mould will cast cylinders, all the same length.

[mdeland]

Yeah, that's a good idea Orville, I agree whole hardly! Getting rid of the different bullet noses would be a huge step in consistency of alloy strength testing.

[James]

Reading “The bullets flight” by Dr. Mann he used oiled saw dust to recover fired bullets for inspection. He states even jacketed bullets of bore size obturate to groove diameter.

[BFD]

I would suggest using a cylinder of the different alloys so the contact points in the press is always the same. A Corbin core mould will cast cylinders, all the same length.

I think this is absolutely required, but destructive analysis is an entire field of engineering, and I ain't no engineer.

That said, I think you are asking two different questions. The first is
1. How much will various alloys resist deformation/slumping. That can be answered with identical cylinders of different alloys. I would not cast them from a core mould - I would swage them in a bleed die mould. Probably a Richard Corbin press and die set (they are stronger than Dave's). But cast would work if that's what was available.

2. How much difference does nose shape make. This can be dealt with using different moulds cast from the SAME alloy. Preferably from the same pot/batch of alloy. But keep in mind, that this question ignores the mass/inertia effect since force is to be applied by a press, not acceleration from behind, where nose weight may affect deformation (more nose mass being more resistant to accelerating). So, I'm not entirely sure this will really tell you which noses will perform best in a rifle.

Last, you will need some objective measure of deformation. It will require a time as well as spatial variable. You can deform lead with relatively little pressure if you are willing to wait days or weeks for it to happen so time and distance need to be constants somehow. Like I said, I'm not a Destructive Analysis Engineer, but I've heard about them.

I'm happy to spreadsheet anything but that doesn't guarantee that a reasonable analysis can be conducted.

Just thinking out loud.

[bruce m]

brent,
your point no 2 is relevant and important.
and I ask again is a squeeze going to tell what a hit does.
bumping up is all about inertia of the bullet resisting a sudden hit in the rear.
Kenny and kurt,
even if the medea receiving kurts bullets is not consistent, the barrel interior is.
this means that you have to read what is not affected by receiving medea, and that is rifling marks on the bullets.
even if the bullet is bent into a u shape, these marks still exist as imparted by setback and slump will tell the story.
interesting how the grease grooves on kurt's greasers have closed up on firing compared to pre firing.
bruce.

[Distant Thunder]

If your asking about compression of CAST bullets I think you need to use CAST slugs (cores) in the test. I would think pre-compressed slugs would react differently than cast slugs. You would just need a larger sample size with the cast slugs to see a true picture of compression.

That being said, I agree with bruce, squeezing is entirely different than a sudden, overwhelming force from behind. I don't think a press is going to tell you the same thing as actual firing would. That does not mean the information would not be useful, just that you're not testing the same kind of force.

By all means, test away! I'll be following this effort.

[BFD]

If your asking about compression of CAST bullets I think you need to use CAST slugs (cores) in the test. I would think pre-compressed slugs would react differently than cast slugs. You would just need a larger sample size with the cast slugs to see a true picture of compression.

Nope, not the case. And it surprises me too, but at least for lead:tin alloy, squeezing vs casting result in the same thing.

[Kurt]

I checked to see if a cast core gets harder when I run it through my swage press and I can't measure the difference with what I have for testing. My alloy I use for the .45's is 18# lead, 15.2 OZ tin, .8 OZ of antimony and it gives me a dimple diameter .080 depending on how pure Rotometal's lead is and it's the same after I swage the core through a bleed off die to get a precise weight before forming the bullet.
You cant compress pure lead but you can make it flow by compressing it if there is an outlet.

[Distant Thunder]

Brent,

I wasn't really thinking that swaging would harden the alloy, though most metals do work harden, more that the consistency and density would be different. Swaged is much more likely to be a uniform density, lacking any voids and such that would be commonly found in cast. That was the reason for a larger sample, it would weed out to some extent the results caused by any of those voids or least minimize how they would affect the findings.

I'm already in way over my head and am probably totally wrong, you would know much better than I would. It's just that if I wanted to know how apples hold up to compression I wouldn't necessarily work with oranges. That's all I meant. Not as many of us shoot swaged bullets as those of shooting cast. If you want to know how cast react to pressure test cast. Just my thoughts.

[beltfed]

As I just said in the Primer thread:
"Impact Extrusion/swaging" is what we are really dealing with
"Inside the Rifle" when it goes bang

A person might be able to somewhat better simulate the Dynamics on the bullet of what goes on in a rifle barrel
by some kind of uniform impact on test slugs.>>>?????

beltfed/arnie

[beltfed]

Just thought of it.
Went and checked in my copy of Dr Franklin Mann's "The Bullet's Flight"
He did "Impact Extrusion" of bullets by firing 185 gr Zischang 32-40 bullets from short barrels in a fixture
From 1/4", 5/8", 1",etc. in front of chamber, various lead/tin alloys.
He variously caught the bullets in snow or in oiled sawdust, "with minimal additional damage"
Example: bullets fired from the 5/8" barrel and through a 3" 40 cal barrel that was tightly bonded to the
32 cal with a threaded sleeve: , upset completely and took the rifling of the 40 cal barrel.
Black powder was initially used, and then he also
fired bullets over a full case of DuPont Sharpshooter smokeless
He found it took at least a 10-11" barrel for the bullets to emerge at original base diameter