Couple weeks ago I posted about this. But I was being hasty. As my numbers were only simulated.

Week ago I posted that I exceeded the muzzle energy of 380ACP with unmodified 8mmK blank.

426.1m/s or 295 joules.

I shaved the 10mm of the handle. Making the total lenght 17.3mm.

Sometimes the steel cases stick so hard to the chamber that they need to be violently hammered out. Hammer is not necessary but something with heft is needed.

Gemini estimated the chamber pressure to be 3800 - 4500 bars with the unomodified steel case 8mmK blank.

I had one brass cased 8mmK blank laying around as I had measured it's internal volume. (It's higher than in the steel cased blank).

I used 208mg of double base propellant from 25 caliber nailgun blanks. The strongest short Black loads have 200mg. That seemed like a good amount for testing.

I am used to making 400mg charges but that's in my 9mm bore zip guns.

I know that the pressure inside 6.35mm bore (mine is sligthly under 6.3mm). Is very high.

My intention wasn't try to exceed the 9mm parabellum power. I just wanted to test if the brass shells eject more easily after high pressure firing.

And they do indeed eject easier. Some light taps with the handle portion of the zip gun was enough. No need for violent hammering.

The measured velocity and power exceeded my expectations.

581.4m/s or 550 joules out of 70mm long (short) barrel.

Exceeding 9mm parabellum energy by wide marging.

I asked Gemini what was the chamber pressure. It calculated from the average pressure with multiplier of 2-3 for blank powder. Resulting in chamber pressure of ~7000 - 10 000 bars. Absolutely nuts.

The nailgun blank powder probably sits in the higher end of the estimate. In the nailgun there's only ~1.5cm long distance to accelerate the bolt before the gas is vented. So it's extremely aggressive propellant. I also compressed the charge. (That's how they are in the most powerful blank loads).

My zipgun has calculated barrel strenght (rupture pressure) of little over 10 000 bars. Very little safety margin.

Rupture pressure for very short peak impulse is about 1.5 times higher than the calculated burst static pressure.

But the bearing that I have used to reinforce the barrel doesn't like expanding. So better not push it further.

I am not a fan of the bullet keyholing and blank powders and rifling do not mix well.

But 7mm tungsten carbide ball weighs 3.2 grams. Almost exactly the same amount as 25ACP bullet.

The larger bore gives bit room to increase charge. But at the same time the steel cases have smaller internal volume.

I want to hit target velocity of 600m/s.

That should be within safe limits.

It has been studied that about 600m/s is optimal impact velocity for handgun bullets. The study wasn't made public so not sure about the results. But I suspect it's a sweet spot kind of deal. Higher velocity is harder to achieve. Not worth the extra lethality.

7mm tungsten ball has similar frontal area than the 7.5FK F9 bullet which is the most lethal handgun bullet. At 3.2 grams it's lighter and has less muzzle energy but should be devastating and penetrate deep enough in a human target.

7mm tungsten ball flying at 600m/s also pierces level IIIA body armour with ease.

So have I now perfected the zipgun/pengun?

Tungsten carbide balls will fix the keyholing issue and provide armour piercing capability.

I could increase the energy further with 32 caliber 4.6 gram bullets. But those will keyhole. So the wolfram balls are superior.

I could probably still shorten this. But the 90mm long handle is already short. Shortening it will ruin ergonomics. The barrel could probably be shortened without much loss of power as the blank powder burns so fast. But the design is already short enough. It's very conceivable.

What do you think?

Currently making a black powder Derringer. 50 cal bore with a bore length of 2 1/2 inches long and a total barrel length of 3 inches.

Aluminum flatwork is about as easy as it gets in the metal milling department. Both from the perspective of testing the machine as well as from a workflow and milling skills perspective. So that's what I did first. The part is a trunnion plate from Mostly Peaceful Machineshop's SVTR Alloy design as that's a design where the side and trunnion plates apparently do hold up as aluminum. While this type of work isn't an impressive test of the machine, I did say the tests would be incremental. So yeah. It also was a great way to teach controller software (CNCjs), the fusion360-to-machine full end-to-end workflow, and some other elementary concepts because I'm also trying to use the series to convince more people to pick up CNC too. So it's incremental in the skills department too.

Next project will be a decent leap up though. Vise work, tramming, 4 ops, bigger end mills, more complex feature milling, the works.

Finally picked this project back up after a major set back. Do you guys think this hammer has enough kick behind it or do I need to make more springs?

This is a proof of concept for captive piston ammunition. Due to my inability to draw specialized casings, I had to get creative and make a new threaded case head. The holds the primer and allows for it to be loaded from the bottom. Since the piston has to go through the modified case head, I couldn't put the appropriate shoulder on it and instead opted for a large thin walled cavity in the piston. This is where an appropriate charge of extremely fast burning powder would be. During firing, the thin walls blow out and obturates to the inner case walls. I tested this with just a 209 primer - it was silent except for the firing pin dropping. The piston is jammed firmly into the case mouth with no sign of gas blowby. The bullet was jammed ~3" into the rifling. I look forward to finding the correct powder load for this and hopefully enough to get a bullet out of the bore completely.

This is on an approved Form 1.

Onde acho o kit de molas da AR-15 buffer spring, estou seguindo o guia do the gatalog para FGC 9 MK2 mas as molas estão com o link suspenso e algumas eu não acho, como faço para prosseguir?

Got it to be much quieter than the previous version.

I know you need a grinder and welder and files, but what type of welders will be good enough that’s still a beginner welder? And just a hand grinder will do? And if so what blades would y’all recommend, and with files should I just get a bunch of different sizes?

All feedback will is appreciated and also any tips cheers.

it seems the weld dot for the fixed firing pin had some bubbles, it broke off at the base on firing. should be a simple fix. I cut a replacement spring spacer/buffer out of some thick rubber mat, it worked quite well. next I just need a latch to stop the barrel rotating off when it shouldn't and some iron sights.

I'm new to building, is there some sort of guide or set of videos I can look at? I've looked pretty hard online and have only found a few vaguely helpful things. I'm well aware of what's needed and the laws surrounding it but how does anyone find out how to put together a parts kit? Thank you.

The main challenge in DIY a rifling button lies in evenly spacing 6 grooves around the

circumference and cutting them at a specific angle. This method combines a high-speed steel (HSS)

rod with a hexagonal indexing jig to ensure a 60° rotation each time. Combined with a sliding

angle grinder stand, it allows six grooves to be ground evenly.

A few weeks ago I posted a video talking through the precision setup of a Desktop CNC that I am testing to see how far it can be pushed in the gun-projects space. That process leads to a fantastic setup. However, while filming for the first 3 projects I have found 2 additional recommendations and one optional thing that make the setup even better! In case anyone is following along I wanted to get this update out ASAP as- order of operations being a pain- some of the recommendations need to happen pretty far upstream in the setup process if you want to do them. So hopefully I catch anyone about to follow along before they go and do the setup work and potentially have to redo parts of it.

If you have no idea what I'm talking about, I'll link to that earlier post down in the comments.

Let the shenanigans begin!

test firing went great, that was the first and only take. my temporary plastic spring spacer is no more, but the gun itself is fully intact. I also made and tested my first real bullet trap. the casing ejected, but ended up stovepipeing. not that that's an issue, since this is very much single shot. next and last step is to make a catch to prevent the barrel rotating out of it's groove once it's in place.

estoy buscando los planos u una guiá de como hacer la caja de mecanismos del AK47, lamentablemente no los encuentro por ningún lado, si alguien tiene algún plano u guiá me lo podría pasar?

Gracias!

It actually shoots really well! Probably thanks to the massive weight. Ha! But whatever, she's a chunky girl and I still love her.

Hello everyone, I recently got myself a Colt 1903 Pocket Hammerless Type 2 frame with the hopes of rebuilding it. However it’s starting to get a little pricy having to buy each individual piece. So I found a guy who is selling basically an entire lower parts kit, however it’s for a type 1 model. Are these parts mostly interchangeable?

Why does my Slamfire black pipe shotgun emit a flame about 1-1/2 seconds after discharge?

Absolutely insane, I want one.

What you guys think? Single or double action?

Did this last year on a VERR slantback, In my experience, I skipped the scratch-start box and waited for a unit with a foot pedal and HF start. Fir setup , I grabbed clamps and measuring tools from penn tool Co since they carry Mitutoyo and Starrett. MSC. is decent alternative.