Why lead v bismuth v steel v tungsten can't be interchanged?

[cpileri]

Can someone explain the physics/internal ballistics or dunamics that explain what and why the various types of shot; lead, steel, tungsten, etc cannot be interchanged in a load?

Is shot weight not shot weight? 7/8oz of lead is 7/8 oz of other shot (ok, in the real world, shot column will be longer if steel since its less dense... anyway pls explain!)

Assume everything else, hull, powder charge, primer, wad and overall lenght and crimp are the same, what happens to pressure, velocity, other characteristic when shot metals are interchanged without changing the weight of the shot?

let me start w the basics observable:
which shot metal, loaded to same weight w same components, produced the lowest-to-highest pressures?
tungsten vs tungsten matrix vs Lead vs bismuth vs steel?
or, if there is a correlation: most-to-least dense gives lowest-to-highest?maybe?

and if this is so, is it only due to column height?

or, as suggested, is a softer shot more malleable when attempting to bridge in the bore (i.e. squishes as opposed to making the pressure force it through this semi-obstruction), and thus it has to do w the softness/malleability of the metal?

or a combination of the two and/or other forces?

but first, just what has been observed: which produces what pressures?

C-

[dverna]

I am not an expert. Here are my thoughts.

I doubt that the type of shot has much effect on pressure. 18 gr of Red Dot should not care if it is driving 1 oz of lead shot or 1 oz of steel.

Your premise of shot cup length makes sense as it relates to the wad needed to fill the hull. Wads for steel shot are also heavier than those for lead to provide some added protection for the barrel.

Don Verna

[cpileri]

summary of answers from other site:

looks like no one ever has done the head-to-head (as close as possible, at least) by loading a one ounce 12ga 3"load, starting w steel in a tungsten-and-steel safe wad(*), maintained a set shot weight of 1oz, set powder charge, same hull and uniform crimp, same primer; then changed only the shot metal type but kept weight constant (*), and sent it off for testing?

Just to isolate the variable of shot metal on pressure/velocity as closely as possible. Hmmm...

C-

(*) Lets say a TPS wad; starting w the least dense, steel, and using felt buffer wads inside the wad cup to make up for loss of column height as shot is changed to more dense metals; so as to be able to crimp the unchanged hull length properly. Close as possible, admittedly.

[Garyshome]

Hard tom take a chance with my shotty. don't want to mess it up!

[cpileri]

you know, I am seriously considering paying for the tests now.

I'd need to find a powder suitable for all shot metals, then I would use a TPS wad and start w steel shot to see how much weight makes the wad full without overflow.

Then go to next dense metal, same size shot, and use a spacer to make the bcolumn to top of petals for crimp. admittedly, it would be "as close as possible".

repeat w next on to most dense metal.

if only for hypothetical knowledge sake.

C-

[OnHoPr]

I noticed that the last couple of months cpileri that you have been looking at a lot of data and asking a few very good and interesting questions (are you having fun) that in ways is hard to define or answer. A couple of years ago you would of got into probably a lot better discussions on the forums that I frequent about wildcatting for slug shooting. I don't know why it fizzled. There were in depth discussions of slug shooting all most as good as the cast boolit sections of this forum. Maybe component lacking or the only trap shooter making comments once in a while, I don't know. But, yours, hubels, and a few others do make interesting comments of thought at times. I'm truly not sure but not weights but densities and shot column length might play different roles in the initial peaking of pressure.

[cpileri]

That's kind of what i think as well.
there is also the "bridging" of pellets in the bore, and hard pelets dont squish as well as lead/bismuth so IF they bridge they will increase pressures.
This forum is where i prefer to ask questions: more friendly responses.
i tried this question on shotgunworld and got a mix of useful, thoughtful and @-hole-type responses. I can do without the ...well... you know which type of response.
Here in the shotgun subforum at least, the worst I get is "i dont know" and usually followedd by a well wish for success. Way better.
I am brainstorming a set of loads to send off to test this phenomenon, or at least be some starter data.

So that you dont have to go read through the "-hole's responses in the other thread, here is a summary of the load proposal:
head-to-head (as close as possible, at least) by loading a one ounce load, starting w steel in a tungsten-and-steel safe wad(*), a set shot weight, set powder charge, same hull and uniform crimp, same primer; then changed only the shot metal type but kept weight constant (*), soft maybe styrofoam spacer on top of shot to keep crimp height te same, and send it off for testing


(*) Lets say a TPS wad; starting w the least dense, steel, and using felt buffer wads inside the wad cup to make up for loss of column height as shot is changed to more dense metals; so as to be able to crimp the unchanged hull length properly. Close as possible, admittedly.

if this data can be gleaned from existing load manuals, I havent found it. hard evidence would take the form of load data, showing the EXACT same components listed with a given weight of shot of the various shot metals/alloys; comparing them to one another for velocity and pressure in the same length barrel. softer evidence would take the form of similarly comparitive posted load data with components 'pretty close'. soft evidence may or may not be convincing, depends I guess on how close the components match.

[OnHoPr]

c-: (*) Lets say a TPS wad; starting w the least dense, steel, and using felt buffer wads inside the wad cup to make up for loss of column height as shot is changed to more dense metals; so as to be able to crimp the unchanged hull length properly. Close as possible, admittedly.

Yes the shot column will change, but maybe just egg carton or the like OS wads to keep the same cushion beneath the shot.

[cpileri]

Actually, the fellow (Hawglips) who has done all the work w super dense tungsten (18g/cc) shot says put the cushions OVER the shot; that way all pellets start in the botom of the cup and the cushions act simply as a placeholder for the crimp.
Since i am only testing velocity and pressure, their effect on shot pattern (bad) wont matter for this purpose.

C-

[cpileri]

i think i found a likely candidate to test this out.the answer came from BPI's Small bore loading manual. There were a couple powders that crossed the gamut of shot metals; blue dot and long shot. Some others probably would work, but there is no data in the books for all the metals.
So the experimental load will be:
410 bore, 3" fiocchi hull, fio 616 primer
14gr of blue dot
tps-410 wad, unslit (with dacron or styrofoam fillers as above to make crimping possible and keep shot in bottom of wad)
overshot card, roll crimp

shot load will be 100gr of each: steel (7g/cc density), bismuth (?? g/cc), lead (11g/cc), hevi-shot (??g/cc), and tungsten super shot (18g/cc)

now I just need to find 500gr each of pellets the same size. What's the smallest steel shot made?

wad will be unslit to avoid damaging anyones chronograph, since I am not testing patterns anyway.

14gr Blue Dot in this load gives 1590fps/9.6kpsi

Other loads are WAY light for usual loads, so the powder charge should be safe enough- risking a blooper?- for the test.

Hope this is interesting.
C-

[Hogtamer]

Carl, I loaded copper coated steel BBs from Walmart a number of different ways. What I thought would pattern best was the worst...so here's what worked the best. 2 3/4 Fed hull, --- grns Longshot, x12x OP seal, thick Mylar wrap, insert a 16 ga nitro card and fill "cup" with 90 BB's . The BB's weigh 5 1/8 grns each, so figured about 1 1/16 oz. The Mylar is tough enough to protect the barrel where regular wads are not. These are NOT pressure tested but no visible evidence or recoil to indicate excessive pressure. This load put 22 pellets in a 14" x 14" square @ 40 yds. Out of modified 28" barrel 870. Don't recommend full choke. More restrictive shot cups (multimetal long wads and even a 16 ga hull cut and used as shot cup were total failures. Regular wads are too soft. Caught a lot of grief about whether they were legal or not even though local warden says ok. They passed the test with the density meter they use to inspect shells.....FWIW

[Cap'n Morgan]

If you change the shot column height you are basically changing the seating depth. With the fast burning powders used in many standard shotshell loads this can lead to problems. Even "solid" wads, like felt or stacked cardboard discs will compress some during launch and replacing them with e.g. plastic wads for steel loads will increase pressure.

[cpileri]

i got some comparitive data from Hawglips on SGW who subbed 1/4oz of steel shot w 1/4oz of Tungsten super shot, and here are his published results:

Here's the original data using straight steel per Alliant:

Fed GM
Fed 209A
32 gr. Steel
TUPRW12
1-1/8 oz steel
1425 fps, 9600 psi

Here's is what I did with it, not exactly apples to apples since I used a different hull, and cushion under the shot due to volume reduction with the TSS:

Federal 2-3/4” clear, new, primed
Steel 33 grains
TUPRW12 wad
1 x 1/4” 20 ga. Cork
(1-1/8 oz):
1/4 oz TSS
7/8 oz Steel
Fold crimp
1348 fps, 8048 psi

Federal 2-3/4” clear, new, primed
Steel 35 grains
TUPRW12 wad
1 x 1/4” 20 ga. Cork
(1-1/8) oz:
1/4 oz TSS
7/8 oz Steel
Fold crimp
1434 fps, 9362 psi

So in the first load he ADDED a grain of powder, added a cushion, kept the same total weight of shot; and the velocity and pressure went DOWN.

SImilarly, in the second load, he added 3 grains of powder and a cushion, and the veolcity and pressure were now on par w the original all-steel-shot load.

Very interesting!

C-

[williamwaco]

I think you are asking the wrong question.

The real problem would occur during the trip to the bird.

The more dense pellets would out run the less dense pellets ( assuming the steel pellets didn't make oatmeal of the softer pellets.) Then your shot string at 40 yards would be much longer ( and perhaps wider ) and either way less dense.


.

[cpileri]

Sure, and that's exactly what Hawglips found.
But for now, I am only interested in the pressure changes w shot metal substitution in isolation from other variables.

The question is mostly academic, since the lethality of dense metals is much higher over less dense ones.

patterns, another story altogether.

C-

[mnkyracer]

IMO, as far as adding felt or other material to the shot cup, it should go over the payload. This would help to alleviate pressure differences due to set back. Material under the payload would cause a cushioning effect. The extra cushioning may help or hurt and can be played with in the future, but for testing/comparative purposes, shot should be at the bottom of the cup.

Just my thoughts.

[cpileri]

So I got 3 leads out for getting this onfo, 2 of which involve me sending loads (and money) for testing.
I emailed Tom Armbrust, but havent heard back. i am hoping, since I understand he is a real wealth of knowledge abt such things.
Precision Reloading will test my loads. They require 6 of each load, one fo which will be disassembled to check components, and 5 will be fired for $25. So for my 5 loads, it will cost me $125 plus shipping. I am loading them now, and will probably send them after Christmas.
I also emailed BPI and their ballisitican ("the curmudgeon") says they are busy w hunting season right now but printed out my question and will get back to me later, probably January 2014.

So in the mean time, I am loading the rounds: i gathered supplies and here is how it worked out.

Hull: Fio 410 3"
Primer: Fio 616
Powder/charge: 12gr Blue Dot
Wad: BPI's TPS (slit, as no unslit available) powdered in hBN
Payload: 88gr of each shot type
overshot; pink foam filler (*) plus 410 mini-nitro card over it all
roll crimp

(*) the pink foam was cut w a punch, each load getting slightly different amount based on available empty space above the shot. Each 'plug' of pink weight 0.4grains.
the steel loads get 0.4grains of foam
lead gets 0.6gr
Hevi-shot gets 0.6gr
Heavyweight 0.8gr
and
TSS gets 1.2grains of foam.
At maximum difference then, (1.2 of 88= 1.36%) the TSS loads are 1.36% heavier than shot alone. And the difference between the steel (88+0.4gr=88.4gr) and the TSS (88+1.2=89.2gr), makes the TSS loads 0.991% heavier than the steel payload totals. I figure that small a difference should not matter too much in the tests.

Every component for every load was individually weighed by hand, FWIW.

I will try to post a pic of how much space each metal takes up in the shotcup of the wad.

C-

[cpileri]

Here are the TPS wads w shot, left to right, 88gr each: steel (7g/cc), lead (11g/c), Hevi-(12g/cc), Heavyweight (15g/cc), Tungsten (18g/cc)

85130

[cpileri]

pink foam filler

85131

[Greg5278]

CP, I wouldn't put much Faith in any Info from BPI. They released 2 Sabots that sucked, and the loading Data was a Joke. Their quoted Velocities were as much as 500FPS higher than reproduced by Reloaders. I have their old Slug Manual, and some loads cannot fit as listed. They are so oversize that the loaded Round is too larger to Chamber, even if you were forcing it into the chamber. They made good stuff, and had some good info, but things have changed in the Fackler Family running the Show there. I give them the minimum Business that I can. They often substitute Hulls on me, without asking, and lose track of Inventory in the Warehouse. An Internet search should show some of what I'm talking about, particularly the Sabots.
Greg
AKA 12 Bore

[cpileri]

Greg,
Thanks. yeah, i keep hearing that some of BPIs data might be fanciful.
If Tom Armbrust never gets back to me, i may just have no choice but to send off these 410 loads and see. He is probably the one guy i really really want to talk to about this topic. I also hear he is not much of a computer guy, so i just hope he gets the email.
I hesitate to pick up the phone and "pester" people, nowadays; but if he truly prefes it, I might.
Sure woudl be nice if BPI or someone who has thousands of loads tested might have already done this, and would be willing to share the data.
And maybe the Curmudgeon has some old, reliable data that he will share; though I wont hear back until Jan 2014 or so.
Ever hopeful, I guess.
C-