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Kopsis

@ Kopsis @forum.guncadindex.com

Posts
3
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141
Joined
4 mo. ago

  • Recommendations Please :)

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  • Unless you're content using 22LR, fully DIY 3D printed self-loading handguns just aren't currently viable. Even those in 22LR are challenging builds with questionable reliability. If you want a reliable DIY semi-auto, you're going to have to settle for PCC/PDW platforms. Even with those, the barrel is a bit of a barrier. DIY is possible, but you'll have to master the electro-chemical machining (ECM) process. Barrel liner builds are only realistic for 22LR due to the enormous pressures involved in center-fire handgun ammunition. But note that in the US, commercial barrels aren't regulated. Any local gun shop will be happy to sell you one in a cash transaction with no paper trail.

    That said, relying on a 3D printed firearm for personal protection is questionable at best. Unless you're legally restricted, pick up a law enforcement trade-in 9mm handgun or a pump-action shotgun (both can be had for just a little more than the cost of a 3D2A DIY build) and call it a day. Think of 3D printed guns much as you would a "curio and relic" antique. Cool to own and maybe safe to use it at the range, but not something you bet your life on. I love my Urutau, but it's had one OOB that destroyed half the gun and the rebuild is now on its third firing pin. Lately it's been running good and will shoot a full mag without a failure, but I also know that the chance of something breaking or wearing out on the next shot is orders of magnitude higher than even many antiques.

  • What should I build? As a first time

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  • Handguns in general are not the "sweet spot" of 3D2A. Consumer printers and the materials they can handle just can't produce strong enough parts in the sizes that make sense for most handguns. So when it comes to handguns you basically have two reasonable choices:

    1. Any of the single-shot 22LR designs. Building one of the Harlet/Harlot/Gambino/Cabfare or their derivatives is sort of a rite of passage into 3D2A. These are complete DIY builds and will teach you good fundamentals that will help you on more advanced projects.
    2. A "parts kit" build where you take all the parts from a mass-produced handgun like the Glock and print your own frame. I'm personally not a fan due to the relatively high cost (cheap parts dramatically reduce reliability) and the limited knowledge/experience gained. But if you just want a range toy you can mag-dump into trash, this will get you there.

    Avoid the NAG (Not-A-Glock) permanently. Avoid the NULL22 and other NAG derivatives until you have experience with a simpler full DIY build. Same for the revolver designs.

    Assume your first build is just that -- your first, but not your last. Keep it cheap and modest and use it as a stepping stone to reach more ambitious goals.

  • Pa6-cf vs pla+ dimensional accuracy

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  • You need to calibrate by printing an object with known dimensions in each axis. Then measure the actual values on the printed object (you'll need a set of calipers with better than 0.1 mm accuracy). From that you can determine scaling values. Most slicers will have at least an overall scaling value in the filament settings. Orca and its kin have separate scaling for XY and Z. You can also scale the object itself manually in the slicer, but using the filament settings is better because it will be applied automatically for everything you print using that filament profile.

  • Favorite advanced filament brand

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  • Siraya Tech PPA-CF is my current "go to" for parts that need more capability than I can get from PLA+ or PCTG. Bambu PPA-CF edges out Siraya in most (maybe all) performance metrics, but for me that's not enough to justify 2X the cost (at sale prices, 3X normally).

  • Suppressor Material

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  • Annealing isn't for strength, it's for heat tolerance. PET-CF, for example, increases its HDT from 80 °C to around 180 °C after annealing. Nylons see a less dramatic but still significant improvement. For frames and receivers that may be a don't care, but for suppressors it's a big deal.

  • Reddit’s Cofounder And CEO Steve Huffman Is Now A Billionaire

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  • Actually, what's profitable is being anti-2A only after turning a blind eye long enough to amass a wealth of data that can be sold to train AIs to detect/block 2A content. I really wish the folks in the FOSSCAD replacement subs would realize that every post and comment they make is going to ultimately be used to improve anti-2A tools.

  • Suppressor Material

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  • Any of the "engineering-grade" materials (PA6-CF, PA612-CF, PA12-CF, PPA-CF, PPS-CF, etc.) can work well for suppressors assuming:

    1. Your printer can handle them.
    2. You can properly dry the filament (drying at > 80 °C).
    3. You get the print settings right.
    4. You can properly anneal the parts (annealing dry at > 100 °C).

    Technically, achieving good layer adhesion is the biggest challenge. You need a somewhat controlled environment so you don't overcool the layers and you need a printer that can maintain extrusion temperatures of 300 °C or more with margin. Process-wise, people often try to take shortcuts on drying and annealing resulting in poor strength and lack of heat tolerance.

    What you'll get with the advanced materials is reduced baffle erosion thanks to the greatly improved heat tolerance. But it's still fairly easy to melt one down with high-volume, high-rate fire.

  • Range Day with the Urutau

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  • Not nearly as quiet as a big can like the FTN, but I don't have any way to quantify. It does take some of the "edge" off but it's not hearing safe. If I had to guess, it brings the 9mm down to about the level of an unsuppressed 22LR, so probably a 10 - 15 dB reduction.

    The advantage the Khrizantzema has is that it's a flow-through design so you get a lot less backpressure than a traditional baffle can like the FTN series. On simple blowback PCCs, that beats up the gun less (you don't get a big increase in bolt opening velocity) and puts less additional gas out the ejection port. On a bullpup like the Urutau where your nose is literally right above the ejection port, that's a big win.

  • Deleted

    Chat, why does 300blk feel just like 5.56 in the hand?

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  • It's originally designed to run in the same rifle with just a barrel change so it has to be more similar than different. But shoot supers out of a <9" barrel and you will immediately know it's not 5.56 by virtue of the fact those around you aren't threatening to beat you with your rifle 🙂 Shoot subs suppressed and you'll likewise know it's not 5.56 by virtue of it actually being quiet.

  • How am I supposed to secure the locking button on the MCXish brace?

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  • Attach the stock to the dovetail. Put a nut in the recess in the stock. Put the spring and release button in place. Put the bolt through the hole by the hinge, capture the release button with it, and thread it into the nut in the stock.

  • Print settings help with PET-CF

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  • There are no magic settings that work for all printers in all environments. In general, start at the top end of specified temp range, no fan, and max volumetric flow no more than half the specified max. From there it's just standard tuning process.

  • Pistol carbine kits?

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  • Risks to personal users if PMF legality changes in the future?

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  • Generally, things don't become a crime retroactively. If the making wasn't a crime at the time, new laws can't change that.

    You may not be allowed to continue to possess things that you already made, but they aren't going to come looking for you unless you do something to draw that attention. At that point whether you bought rails doesn't matter. You're either in possession of a prohibited firearm or you're not.

  • AR15 and M4 rifling buttons

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  • Bottleneck cartridges usually need two reamers. Unlike straight-wall pistol cartridges, rifle cartridges require opening up the chamber to a much larger diameter than the bore. A rough reamer is used to aggressively remove material to get the chamber near the correct size and then a finish reamer is used lightly cut the chamber to the final dimensions. The same rough reamer is often used for both .223 Rem and 5.56 NATO (and .223 Wylde). The finish reamer will be specific to which chamber dimensions you want. Either way you will need two reamers.

  • Which gun as first time complete DIY?

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  • If you're not in a hurry you might want to consider the Decker 9. It's currently in beta but it will be very similar to the 380 version that's available now. It's a very easy (and inexpensive) build and has some cool options like side feed or top feed, different fire control groups, etc.

  • Which gun as first time complete DIY?

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  • Fully DIY 9mm handguns aren't viable yet. Simple blowback designs like the FGC9 don't scale down because you need about 500g of bolt weight. Until someone comes up with a viable locking mechanism, PDW size is about as compact as you can get.

    More modern DIY alternatives to the FGC9 include Rogue/Rebel and Urutau. The Rogue/Rebel designs are very full-featured, but making the bolt is more work than other designs. Urutau is a pretty easy build and a really enjoyable gun to shoot.

    We'll hopefully be able to add the Decker 9 to that list soon.

  • AR15 and M4 rifling buttons

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  • The roughing reamers can be the same but the finish reamers are different.

  • DB Alloy Feed Issues

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  • The printed mags usually feed more reliably (when new) than surplus. The problem with the printed mags is that the feed lips are really thin so you have to print with a stiff low-creep material (PET-CF works well). Even then they wear quickly.

    With surplus mags you'll need to verify the feed lip geometry (they're often bent/stretched) and you will probably have to tune the location of the mag catch adapter.

  • AR15 and M4 rifling buttons

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  • There's no difference in the rifling. The differences between 5.56 NATO and .223 Remington are all in the chamber dimensions.

  • Plasticcatto DD19.2 Update

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  • Looking good! I have a 19 slide collecting dust in the safe so I'm eager to see this sail.