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I press 4 oz end burners (NEPT tubes cut in half to 2.5”) on a homemade tool with a PVC pipe tube support to 6000 psi on the composition. I’ve used riced (no dextrin) hot willow BP, and encountered CATOs until I started waxing the tubes. An identically made motor with a waxed tube flies great, while the unwaxed version would explode violently. I have yet to try dampening the propellant but it sounds like a good idea, especially if you’re able to standardize the moisture content for repeatability. I usually press a bit of Tiger Tail on top of the fuel as a delay, with no bulkhead. Once you get a good method down they’re lots of fun - the thrust profile is different than a core burner and arguably less suited to lifting payloads, but they certainly have a unique appeal.

Got some photos?

Let's consult the ATF, FBI and state and local police departments. Besides... who needs a firecracker with flaming fragments? Bad idea.

Potassium perchlorate without anti-caking agent is much more clumpy and tends not to burn equally unless you have Anti-cake. My favorite and undoubtedly the best Anti-cake is silica powder! I have used it for Ammonium-nitrate fuel oil (ANFO), which is a very HIGH explosive, and also with my Air-float Charcoal, and I identify a difference without anti-cake! Even when making BP, you can you anti-cake for the Sulfur and charcoal. The KNO3 does not need anti-caking because it is hydroscopic, meaning it doesn't rapidly absorb moisture from the air, which is a primary reason for caking.

Remember only BP made of potassium nitrate, Sulphur and charcoal is ball milled with all safety measures and remote operation ,besides it can be used to mill individual chemicals into fine powder with cleaning of media and jar neatly every time. You MUST NOT mill kp based BP or any composition except bp in ball mill. You should screen mix KP and fuel. It is being used as a burst charge and should be coated over rice hulls/cotton seeds etc. No any information regarding to be used as a lift charge.

If you're talking about using it for burst. In your machine wound core " shells ". They will just be more of a salute type effect, than they already are. If you're talking about using it as lift. If you put a heavy enough shell on top of it. You'll have a salute mortar. If you're talking about using it for burst in ball shells. Enjoy. Yes, it's just screen mixed. Usually coated on to rice hulls.

I concur 😎

This has probably been discussed here previously but I didn't turn up any answers in my browsing around. My ball mill ate the dust over this winter and I find myself unable to make fast BP. I've made a few batches with screening and wet mixing, but it's only...meh quality compared to the milled stuff. I've been reading here and it seems many of the more experienced people are using kp. I've never made it before but I might give it a shot. My question is, does kp need to be milled like bp? Or is a thorough screening and/or bag mixing adequate for desired performance? Side note...I do have a vibratory rock polisher laying around. Might that substitute for a rotating style mill?

@Carbon796's math appears correct. I'm pretty sure (somebody correct me if I'm wrong) that you'd need to subtract the area of the spindle hole on the hollow rammers from the outer area to get a close-to-constant PSI throughout the spindle section. I'm also pretty sure everybody ignores this (it's probably beneficial to have the comp around the spindle compressed more heavily anyway). For example on Caleb's extreme strobe tooling it looks like the hole diameter in the longest rammer is 0.39" on the 1lb tooling, if I subtract that it gives me a pressing area of 0.322 instead of 0.442... makes a big difference in these calculations. If I did the math right pressing at 438 on the press gauge will give you ~9600psi on the comp instead of 7000 which is a kinda huge difference. The next rammer will be lower, and it'll finally be 7000 at the flat rammer.

I've never used the monocapa prime. But. It works on the same thermitic principle, of what I used. So my guess is, it should be fine. You're just not going to get those lit, with only a thin coat of scratch mix prime . . .

Ok thanks for the formula! I’ve been looking to try some KP/Al flitter/wave comps. Would monocapa light this, or does it need an even hotter prime?

For your flitter aluminum you can try this formula. It is my personal, metal fueled streamer comet comp. .50 KP .15 German flake coarse .15 flitter coarse .10 -325 bright flake .05 IBA/German drk .05 Sulfur + .035 SGRS or .05/06 dex It is harder to light, but the S & IBA make it easier. Use a hot prime. The German flake is thicker/denser than flitters AL. It will light up and hang/float in the air. Much more than a flitter type ( FYI ) but with your materials try .10 or .15 -325 & .30 or .25 AL flitter. It should still look pretty nice.

No problem, let us know how it turns out. I realize I was a bit loose with my use of the word “mesh” in relation to burst charge strength above… Shimizu refers to the grain size of the burst getting progressively smaller in each successive petal towards the center of the shell. Smaller grains = higher surface area = faster/sharper spike in pressure. Coated rice hulls don’t really have a mesh size like granular black powder does, but they do provide a smaller amount of burst composition per unit volume, and have less surface area, than fine-grained BP. Since space in a double petal is limited, using granular BP in one or both petals could make sense for these reasons. Keep in mind that this will make the shell heavier, and if the granular BP is too large, it will theoretically be wasteful, as the grains won’t have time to burn completely before the shell opens.

Thanks. I will try a 4“ inner petal with more booster and finer mesh for the inner burst charge.

Woody's tooling is made with plastic parts that sacrifice themselves to sharp metals cheaply and can be easily and cheaply replaced.

Luckily most of my tooling is homemade with loose tolerances (or easily replaceable parts) so I don’t have to worry about using Ti/FeTi of any mesh. I’ll make some test comets. Thanks for the advice!

Sorry, did I ask a stupid question? I was just wondering the safest way to do it. I am new to pyro and I'm not trying to kill myself.

Yes, that would definitely be one to try. If you have the -30+100 spherical Ti also. I would try both of those before the thinner flake AL. Just be mindful of your tooling. The Ti will ruin it quick. Iirc, I shot a few of those as 2" comets, with the spherical Ti. At a few club meets. And they always impressed.

I currently have all the metals listed in the original post, so 30-60 mesh MgAl is an option too. Maybe I’ll give that a shot. I like the idea of a sizzling comet!

Whatever happened to there are no stupid questions ? Newer, inexperienced people. Don't know, what they don't know. Love your positive encouragement.

" commercially " available fountain tooling. Is generally made to form, some amount of a convergent/divergent nozzle profile.

Yes, IMHO that would be the best place to start, for that formula. With what you currently have on hand. But, I would try to get ahold of some coarse chunky Mg/AL or AL for the future. Iirc the original spec AL in that formula has a really nice sizzle to it, in flight. And a very coarse Mg/AL will almost have a glitter quality to it.

Thank you 👍

Great, thanks! The types of aluminum I have on hand are the coarse flitters mentioned above, as well as atomized 200-325 mesh, bright flake (325 mesh?), and some dark pyro aluminum. Do you think the flitters would be the best substitute for the granular aluminum in the formula?