I`ve been proof testing stuff again, this time i wanted to something amazing. First i wanted to do an experiment with notoxic shot, or should i say varied density shot. Its the experiments i`ve been going on about for about a year. Its taken me a year to get stuff up and ready, because this is actually a slight continuation of my lead vs steel ammunition analysis. I also had a load tested before to essentially tune up a load and have a play with some nontoxic shot.
First i did a ton of research, i needed a hull, primer, wad and powder to allow the load to be safe when the hardest of shot is used to the softest shot. The first the load i had originally tuned was a 2.75", and when i said "tuned", i mean i`ve run a bunch of test shells to get the right powder charge for my series of tests. the powder charge i hope to keep the same throughout the shot density assay, to make sense of some numbers later
on. The 3" hull is to be used and the industry standard cx2000 primer. i went with the 3" hull because of a few compounding things... the large powder charge, and more so the tall nontoxic wad i have personally chosen.
I choose the clcb / gualandi tubo24 wad, it is a tall solid robust wad. I selected this because of one of the shot materials i`ll be using is tungsten or hevishot, i wanted the wad to be very protective.The BP24/28 wad does offer protection. With the BP24/28wad may mean 70mm hulls could be used, but not at that powder volume. I made a decision 3", cx2000, Gualandi CLCB / Tubo24 wad.
The main components are done. the next phase was the powder. In my initial tests i had steel vs lead, and i had 36g lead vs 25g steel shot. The results were as expected, but not too dissimilar, about 100fps and 150bar difference between the two. Hardly groundbreaking stuff, but it was to pave the way for this tests.
I tuned up a load with steel shot and lead, my criteria for the tune up was to get the pressure high for the 25g steel, and then switch out to 35g lead again. But with greater numbers. The number i evidently ended up with was (26) grains of vectan A1. I selected vectan A1 because it is reported to have a really good operating range, and a solid performer. (irony is its one of the slowest powders i`ve used recently, 42g 3" lead subsonics). I know that the powder can seriously handle 36g lead going at very acceptable speeds (not theoretical, actual good speed.) so that was criteria.
So... we have an expected donor load with some spaces already filled in, namely lead shot and steel shot. From a technical point of view as the volume of shot is the same, i can measure shot by a mec 114 lead bar. It drops close to 25g steel and 36g lead. It fills up the clcb wad nice with no overfill. The load and assay is all but complete. the next stages were to buy small lots of different nontoxic shot, and switch out the shot metal for the varied nontoxic shot. I want to thank the pigeonwatch forum for supplying me with some of the components. There are 6 shot types.
12-76-1050 bar HP
26grain vectan A1
Gualandi Tubo24 / CLCB wad
25 gram Steel shot 499 Bar 411 m/s standard
28 gram Pure copper shot 569 Bar 403 m/s standard
29 gram ITX-10 shot 677 Bar 405 m/s HP
32 gram Niceshot shot 688 Bar 387 m/s standard
32 gram Bismuth shot 677 Bar 382 m/s HP
36 gram Lead shot 757 Bar 379 m/s HP
All these have been run through the CIP system, 5 shot string. The HP stands for high performance second tier pressures, thats below 1050bar, and the s2n variation is below that criteria too.
So... those labelled HP passed cip High Performance 1050bar (1050bar MAP) and passed the s2n (variation). The other shells pass the standard presser tier (740bar MAP). The Additional notes are
because sample size is so small, only 5 shotstring. The statistics, the s2n is ultra strict, meaning if they pass they are safe. I cant justifying shooting all those nontoxics (well someone else to shoot them).
To recap, I put different shot by volume in a nontoxic wad. Fired them off in a pressure barrel.
Of all the shells i manufactured, the nontoxic assay proved to me that internal ballistics are quite complicated. infact having lots of data is the key to understanding all parts of ballistics. To calculate the energy i used the ft/lb formula to get the energy levels. (v*v*m/450240), to express this in ftlbs. There were some tests that i have not included in that dataset, because they failed proof. namely HW13, and another. The one statistic i am interested in, is the efficiency of the cartridge, ie powder has energy.
25g Steel 385 grain 1348 fps 1553.8ft/lbs 59.76 ftlb/grain of powder
28g Pure copper 431 grain 1322 fps 1673.0ft/lbs 64.43 ftlb/grain of powder
29g ITX10 447 grain 1328 fps 1750.9ft/lbs 67.34 ftlb/grain of powder
32g Bismuth 493 grain 1253 fps 1719.1ft/lbs 66.11 ftlb/grain of powder
32g Niceshot 493 grain 1269 fps 1763.3ft/lbs 67.81 ftlb/grain of powder
36g lead 555 grain 1243 fps 1904.5ft/lbs 73.25 ftlb/grain of powder
Additional / failed cartridges
42g cartridge t 647 grain 1201fps 2072.7ft/lb 79.69 ftlb/grain of powder
32g cartridge s 493 grain 1364fps 2040 ftlb 78.5f tlb/grain of powder
While that table is interesting, all it says is that the heavyer payload the more energy shot recieves, the cleaner the load burns. The energy is not infinite, x grains of powder can only produce y amounts of energy, no matter what ! There is never going to be more energy created. Essentially everytime we dose a hull we are adding x amount of energy, or x energetics. It would appear that 26 grains of powder in this application has a maximum output of ~2050 ftlbs. If we study the list alittle it gives away the clues, such as 28 gram to 36gram is where this powder really excells, not suprising so, as thats what the powder is marketed at. The lead (Pb) load seems to be right at its powercurve. It really kicks out that energy. Infact thats really good to see 1243fps at 2.5M is still a fast speed. I think the rules are established and confirmed, lightweight shot charges go
fast, but only get given 3/4 the available energy, while heavyweight shot charges go slow with a whole lot more energy.
How can x grains of powder give different energies? The mystery of this isnt as simple. The assay was designed to keep the obturation and the volumes the same. They are. The compression section of the wad is the same. The differences could be that the lighter shot (25g steel) gets given enough energy to move initially, and once the crimp goes its transfered enough energy to move the shot and break the crimp. The heavyer payloads need more energy to move the larger shot weight.
If i do a back calculation to say all the~2050ftlbs of energy of that 26 grain powder charge is converted we would have a 25gram steel load doing 1600fps !
We should note that the lead 1904ftlbs is not too far away from the most energy produced. That heavy lead shot charge must need a lot more energy to move the shot and break the crimp.
Lets talk wads, what does the compression section do? How can we compare the compression
sections, knowing different weights of shot causing different ballistics ? Is the wadding ever more crucial to internal ballistics? There are 1000s of wads out there, they must do something different?
On paper the lead load just rocks, relative fast speed. But the other nontoxic shot at about 32grams seem to be about what this powder can do. The odd uique thing is the ITX 10 seems to really romp home with nearly the same energy as the heavyer lead load. thats 29 grams vs 36 grams. It seems to suggest ITX10 is punching well above its weight. It also seems that heavyer payloads Nearly use all the energy, but are close too or over the "standard" tier CIP breech pressures.
Looking at the data there seems to be a power band around the 32g payload. Its enough shot weight to just work well. Not suprising as its the range its supposed to work very well in. It is very clear that it is right in the middle of the road for this payload. There is a massive energy spike at around 36g of lead shot. Not suprising as its just above the powders intended payload. It appears there is a plateau at some point and any weights above the 32g weight, the energy skyrockets.
The 59-64-67-66-67 ftlbs / grain of powder can all be argued as very close together, 73 ftlb per grain is on a different level, thats the lead load, extracting more energy form the powder. A better cleaner shell. The additional shells were over pressure, a heavyweight tungsten load and a 32g steel non compression wad load. They failed the CIP High Performance tier, but the energy data is still very useful in this application. Even at very high pressures the shell energy output is very close to the really good lead shell. Meaning the lead shell is pretty much, very efficient.
One experiment that was conducted alongside was on a similar lines to the previous
experiment. Infact it was crutial.The comparison between compression wad and a non compression wad. this would be very hard to compare. but not entirely. First everything has to be similar, exept the wad, because the wad will be different, so will the shot. The test has to be done like that. What we have is an array of components. The payload needs to be the same, Different shot types must be used. The test is 32grams of steel / non compression wad vs 32grams Niceshot / Tubo24 wad.
The results came back and offer an insight into the internal ballistics. Comparing how that compression section affects that powder charge. The first thing thats noticed is the 32g Niceshot with compression section came in at 688bar. The 32g steel shot non compression section just straight doubled in pressure to 1282bar or 18000psi in old money. There is no compression section for the gas to expand into, so the breech pressures just skyrocketted up. There is no second questioning it, just straight doubled. This says a few things, pressure is created in the chamber, thats a no brainer. The volume that the gas can expand into will affect the breech pressure, thats measured 1" in the chamber. This Steel 32g load was used as a control for the experiment to extract the most energy from the powder. The 42g HW Tungsten load was a heavyweigh version, but it failed on pressures, but gave out the same energies as the 32g steel. Thats cool.
The future testing.
At the end of all this, we have data and some great shells. The future work i take from these tests and the data are that Faster powders needed to be used for the 25g steel shot load. The 32g loads are fine. The 36g payload / powerband is probably the best thing to exploit, loading up 36g of premium heavyweight tungsten shot, plus packer / wad filler. Duplexing Tungsten and steel shot might be achievable. The 32g loads could tested in the same way, ie more plus packer / wad filler and 32g of heavyweight tungsten shot.
-some of you have seen this data before, this is the full written article that i planned to write a couple of years ago.
i`m planning on doing some other stuff, maybe the same in 20 gauge, and a fibre wad 12 gauge version, thats lead / Bismuth / Niceshot.