First I will say it’s not necessary of course. The design whilst very advanced for its time, and perhaps with updates could sit quite comfortably with modern pistols. It doesn’t offer much in the way of benefits, atleast in calibers like 9mm. However, I feel the pistol in a higher power caliber could definitely benefit from its robust rotating bolt design. Perhaps something like 7.5 FK. Could of course go bigger like 50AE, 429 DE, 44 automag, 45 win mag, etc. However, those calibers make it far too niche in my opinion despite the fact I love the idea. The 7.5 FK really fits a happy medium of being very powerful whilst also not being crazy and also having very decent capacity. Also, perhaps the rotating bolt design would make it that much softer in simple 9mm to shoot, hard to say.

Anyway, the picture I use is supposed to illustrate my idea of the best way to update the pistol. And thats the way the gun unlocks. The 1898 uses a rotating bolt, but the way it operates whilst simple in theory, is quite complicated to manufacture and from a modern standpoint makes quite a few compromises. The whole slide of the gun rotates as opposed to just the bolt. The bolt basically is the slide. That’s the main issue. It makes charging it difficult as well as making it unable to have sights on the slide. Also, the design of it gives the gun a somewhat fatal flaw where the entire gun is held together in the back end by a singular disc basically attached to the frame. My main idea is to basically design the slide much like an AK bolt and BCG. The gun under short recoil stays locked into the barrels bolt lugs and then the barrel assembly hits a lug in the frame like the 1898 to stop the barrel and begin the unlocking. Using the energy of the short recoil, the slide with its cam groove acts on the cam pin of the bolt and unlocks it. You could have dual recoil springs on each side of the frame like a P38 and an internal or external hammer. Roller locked would also work, but I like the concept of the rotating bolt a bit better.

Is there something wrong with this principle? Because I’ve seen gun designs that came close to doing this but simply not doing it like the wildey pistol, desert eagle and the automag. More specifically the automag since it’s short recoil. I wonder why it wasn’t made more simple. Perhaps the designer wasn’t aware of more simplified rotating bolt designs. But then again, the garand works on a very similar principle to the AK and would have been very easy for him to study at the time. The main issue from what I’ve seen with designs like the automag is that they lack slide mass compared to the barrel assembly. They rely way too much on just simple spring pressure to make it work reliably. The 1898 seemed to operate reliably and had a happy medium of ample slide mass for reliable operation.

But I guess I am just confused as to why this hasn’t really been done before in this way. It reduces complexity compared to the 1898 and certainly the automag. Is there any problems with my engineering logic? Is there a reason this wouldn’t work?

Other changes or updates would include using a fixed ejector like the AK or a plunger spring loaded one like an AR. I wonder if retaining the main sights on the barrel would actually be preferred in terms of insuring greater mechanical accuracy since the sights would be affixed to the barrel and thus always be in the same repeatable alignment. It would be kind of users choice to put either your red dot or back up irons on the barrel. I prefer putting the red dot on the barrel because I would prefer my dot to be the most accurate sighting system. As well as for the fact that if you have the rear iron sight on the slide, you get a better sight radius than if they were on the barrel. But the dot being on the barrel is more cumbersome from a holster standpoint as well as providing an obstacle when you charge the weapon.

Another question y'all might have is why I am interested in the 1898. Well, it’s a neat pistol mechanically. And it was one of the first as well as one of the best at the time. And the rotating bolt does put it on a small list of other rotating bolt pistols. The reason why it never caught on is somewhat hard to say since it was certainly better than almost all of its contemporaries. Ian figured they were just likely very expensive to manufacture and thus very expensive to sell. I also like pistols where the barrel is naked as it were. Guns like the Luger, 1898, C96, automag, etc. It just looks prettier generally to me and from a modern perspective it allows ease of porting anywhere and everywhere on the barrel if you so choose as well as ease of attaching compensators.

My updates would give the slide more cycling mass, greatly reduce its complexity and allow the slide to be used like a conventional slide and allow the sights to be mounted to it is as well. And of course when it comes to updates, I would give the gun a proper slide release, magazine release, double stack magazine, light rail on its dust cover, etc. Also, I use the AK as a popular example of the principle I am conveying. The bolt need not be a direct copy and have the cam lug/pin be affixed directly to the bolt. I think I would prefer the Sig 550s design for the purposes of this pistol idea.

Anyway, tell me what y'all think

I'm looking at a problem, where i'm struggling to make my bolt rotate 45° on a 21mm long cam, because i want to be able to rotate the bolt 90° to change the ejection's side (up or right side) by just turning the bolt before reinserting it into the bolt carrier.

The bolt's body is 16mm in diameter, so the problem is that if my cam is going inside, i have to either restrict the diameter of said cam or the depth it goes (example, a 6.5mm cam can only go as deep as 3mm inside the bolt, else, it creates voids where the cam tracks interact in the middle of the bolt body and create unsupported borders for the camtrack with a void in the middle. Also, if the cam is on the bolt, i have to have either 2 camtracks inside the bolt carrier, or be able to reverse the side of the cam to accomodate both positions of the bolt.

Does anyone has an idea?

Is there a way to determine how large of a piston you need for a given bcg weight and required travel I am using a 24 Lb spring and my bcg weighs 1.4 Lbs i need 5.875 Inches of bolt travel and im only getting about 2" Im running an ar10 mid length barrel with a .125 gas port. Also any input on gas block configuration relative to the gas piston to get more power out of it is greatly appreciated.

You know im something of a gunsmith myself /s

Trying to design a machine gun, and I'm working on the barrel changing mechanism. I was wondering if anyone has resources or advice about designing consistent and well sealed locking mechanisms. not talking about stuff like toggle lock or roller lock, but rather how to maintain headspace in locking systems such as rotating bolt or the interrupted threads on stuff like the M240 barrel, and what to consider when designing them.

I know that the limasix and mfr56 came after the fightlight MCR and ancestor of the fightlight MCR was the ARES shrike and belt fed AR10 which has the gas/piston system above the barrel making it centred instead of the MCR's left side piston. I am thinking it has something to do with ease of barrel swaps and maybe to simplify the belt feeding system. I do have some of my own ideas to make it in the middle. However, I also see some pros and cons to have it either on the side or on top. What is your opinion and why do you think they wanted to put it at the side.

I know you can use the thread feature to makes threads but I am not sure if that is the right way. Is there another way to do it?

Modern gun designs come with many different barrel lengths, either as versions or quick change barrels. This means saying a new gun is Xmm long does not represent how short the gun is, since the competitor can always cut the barrel some more and say it has the shorter gun. I thus suggest a new measurement length which is ACTION LENGTH, the minimal distance required for the action to be functional, without the barrel or accessories. This can include the chamber only in cases like bolt action rifles, and the length of the barrel until the minimal distance to gas port for gas operated systems. To give an example, the action length of an AR-15 is measured from the end of the buffer tube (not the stock) to the gas port. The action length of an AK style rifle is measured from the back end of the rear trunnion to the gas port. Considering the modularity of modern firearms, I think this measurement can more reliably represent the quality of a design in terms of compactness.

I want to make a FOSSCADable multi purpose launcher capable of firing both explosive and anti armor rounds and I want to choose a type of launcher before I design it. I want this launcher to be a "great equalizer" by using common parts and leaving the design open source. The launcher, along with it's ammunition. should also be easy to manufacture and is basically FGC-9's big brother. With this in mind, would it be better to make a black powder recoilless rifle similar to the Irish PRIG or a rocket launcher such as an RPG. What would be more effective/simple and what other factors should I consider?

hi, it doesnt look like this has been asked or answered here so i figured it would be okay to make a new post about it. i have a moderate amount of experience with maintaining, repairing & modifying guns, & ive just started learning to 3d print guns from preexisting designs. i really want to make a gun of my own original design some day, but i definitely want to learn as much as possible first so i dont accidentally do anything dangerous or make something that just sucks. ive been able to find a few pdfs of books that seem like theyll be helpful, but ive never seen a comprehensive list of “required reading” for aspiring gun designers or even any books that cover the subject broadly & thoroughly, most of what ive found interesting & potentially useful addresses something too specific to be of use to a beginner. i was hoping this board could give me enough recommendations to compile a list of introductory educational material i can study until im confident i can design a firearm that wont explode in my hands & perform well & reliably. thanks to anyone who can point me towards useful documents, all replies appreciated :)

I love the design of the urutau and wanna print one with a little more power. Could the CAD files be tweaked to fire 10mm auto or is that too powerful. I'm planning on printing one in Bambu PET-CF and after this project making an integerally suppressed .45 ACP urutau with a brass catch to be the ultimate assassin carbine. I'm decent with CAD and have been using Onshape for a year. This is gonna be my first 3d printed gun and I have a surplus of 10mm auto. Wish me luck!

Posted here along with r/fosscaddevgroup.

For a while I've been designing a multicaliber bullpup rifle known as URSA (Universal Rifle Service Armament). It's designed arounnd modularity and will have a quick change barrel that also swaps out the rail/handguard and optic when you switch barrels. This allows changing barrels to be much easier as you don't have to rezero your optic and can store a premade configuration for a certian purpose. For example, you could have a 300 blk barrel with a suppressor, laser, and red dot for a suppressed carbine. In the same rifle you also could have a 338 lapua DMR complete with a scope and bipod and you could switch between these rifles in a matter of seconds. This would revolutionize infantry logistics allowing for a team to easily switch to mission specific gear and have a commonality of parts between different specialists. I have been wanting to design a "multigun" for a long time and seeing FOSSCADers like John Galt (creator of the MBAR) and Hoffman Tactical (creator of many guns including the Orca AR15) has finally made me bust out my laptop and start designing it on Onshape.

Other features of this design include: - short stroke gas piston system - constant recoil - mdrx style forward ejection -compatability with AR-15/AR-10 bolts, barrels, and handguards - almost entirely 3d printable with off the shelf parts

One of the main concerns I have for this project is what frame should I use and I was thinking of doing a thumbhole stock like the F-2000. I wanted something that would be stronger and easier to carry without jabbing into my back unlike a pistol grip and I heard from one of my friends that thumbhole grips are great for bullpups center of mass. What are the possible concerns with thumbhole stocks and should I just design it with a pistol grip?

The overall momentum given to the firearm is the same, so what does the counterweight cancel?

• feel free to skip this wall of text. I was trying to look up the best “movie quiet” pistol and I know that 22lr is incredibly quiet suppressed but it isn’t deadly enough to quickly kill unless you shoot you’re adversary in the head. I came to a dilemma that the best way to make a movie quiet pistol deadly is to put an frt on it but 22lr isn’t able to hold a high capacity due to it not being able to be doublestack. I also learned about the kel tec pmr 30 which is able to hold an impressive 30 rounds of 22 magnum. The problem is that 22 magnum is very fast and very loud so I came up with a new bullet I call 22sub.
• 22sub is a 22lr casing with a long heavy bullet designed to fire out of 22 magnum firearms. it’s total length makes it exactly as long as a 22 magnum but it has much more bullet per bullet and less propellant. it can be made at home with a simple casting set and then crimped into the disassembled casing of a 22 long rifle. it’s advantages are that it’s a heavier round making it better for suppressed subsonic weapons and that 22 magnum can be double and even quad stacked making it a great option for adding an frt to your gun. as far as I can tell it’s not going to have many problems feeding but since the casing is shorter it might not eject properly. will it work?

I am in need of some advice I have for a micro pistol that I have been designing for a while. It’s a blow forward rotary barrel micro pistol chambered in 10mm auto. I took heavy inspiration from the boberg/bond arms bullpup and am looking for things I should consider adding to the design. this design is mainly a concept but I might build it when I have enough money for a mill. here are some other features I am considering adding if I have the ability to without major alterations to the design:

• continuous recoil: with a blow forward pistol it means that the pistol will have a “rebound” system where the slide never reaches the end of the pistol. instead, a powerful spring transfers the forward motion of the slide to the frame of the gun pushing the gun back into a ready to fire grip. in order to make racking the slide easier, a button will disengage the main spring spring and a much lighter secondary spring will take over.
• stripper clips / single loading: due to using a dual feed magazine it’s possible to manually load rounds through the top. this will make it easier to load loose ammunition and top off.
• very light double action: 3 - 5 pound double action. the double action design I’m using will most likely have an incredibly smooth trigger pull that is also safe enough for pocket carry.
• integrated compensator: a compensator that is bolted to the slide allows it in states that have banned threaded barrels and tames the recoil that come with micro pistols and the 10mm round
• high capacity: magazines will be double stack and dual feed because of the way that rounds in a blow forward pistol are chambered. 3d printed thin grips mean that the gun is kept relatively thin without sacrificing capacity.

I’m designing a double stack rotary magazine that could potentially reduce magazine profiles by a third.

I was thinking a clock spring would work but that would add length to the magazine and kind of diminish the value of a rotary magazine for saving space. There’s some negative space behind the follower and a ramp at the feed lips so a torsion spring could be put behind the follower but it would need to rotate about 310 degrees and that might be too much stress

So I’m hoping someone could help me figure out how to figure out what size and shape of spring to use to get reliable feeding in the most compact form

To start, I am not tech savvy and I am somewhat cursed with anything electronic seemingly malfunctioning whenever I touch it.

I have pretty much always gone to hand drafting my ideas and figured that would be fine I also don’t have much of a workspace anymore after downsizing to a smaller place.

Plus, machine shops seem much more comfortable with a computer drawing than a paper one these days.

I figure it’s time to man up and learn CAD. But I don’t really have any clue where to start or what software to use for these things.

Any assistance would be greatly appreciated.

I'm looking for a set of G19 slide drawings or a model, specifically the bottom of it, the feeding tooth on the slide and the interface with the trigger and out of battery safety. I only found drawings that cost about 20$, but I want to be sure I can't find any models or drawings which cost less.

This is basically what I think should happen with the 25x40mm grenades and what should replace the Mk.19 in service, you are welcomed to give your thoughts and feedback: The US army set out to test new grenade launchers, specifically semi automatic stand alone launchers fed from a magazine and in smaller but smarter calibers (30&25mm). They have three designs from Colt&NG, Barret and FN, which are mostly still in development. One of the main concerns mentioned beyond regular threats such as enemy infantry and light armoured vehicles is UAVs and drones. I think this is a very valid concern, and I think it can be solved better using GMGs and not just launchers. The US army (as many other armies as well) use the Mk.19 GMG, chambered for 40x53mm HV grenades. The Mk.19 and its ammo are heavy and require a squad to be carried. I envision a 25x40mm GMG, small enough to be carried by a single person (with an ammo carrier probably), so a squad can have three or four of them. A slow rate of fire (300 RPM) and a long recoil action for better shootability and recoil management, and a smart sight such as the SMASH-2000 on one or two of them could do wonders against drones. The squad can also engage more targets at a time, and can cover a larger area because of the principal standing behind cluster munitions (8 times the explosives equals twice the kill radius of a single bomb, so for the same amount of explosives it is worth shooting many smaller bombs instead of one big bomb). Disadvantages to the system would be its range, 25x40mm grenades have half the range of 40mm HV grenades, so it might not be useful for battalion level fire. However it does offer better capabilities for units up to the size of a company, and much better ranges than 40mm LV grenades (which is why they are being replaced by said launchers). This is also a step away from crew served weapons, which the army seems to take anyway with its project to replace the M2 with smaller but individual weapons (which perform badly in Gaza right now, but this is a topic for another post). LMK what you think, and what would you add to the features of that theoretical (or is it?) GMG.

I still like my original idea, but its a bit too bulky I must admit. Perhaps a better design for a purpose built PDW. Anyway, this is better as a pistol that can double as a pdw with a telescoping stock or some sort of flip out brace. One of the main things people didn't like about the other design is that its too different from the original C96 and that it was stretching the idea of what's feasible in something still considered to be a pistol. It is still complex by modern standards, but wildly more simple than a regular C96. Despite the bore axis not being as low as the other design, the bore axis of this design is still very low, right above the hand. And I was also noticing that in many ways this design mirrors a Ruger 22 gun in some ways like the rear charging knob, fixed barrel and bolt that operates with an internal hammer like a rifle. The recoil system can be done a number of ways. You could put a recoil spring basically in the same place as a ruger mark IV which is attached to the top of the bolt. And it can also be designed to disassemble exactly the same as well or like a AR and have two captured takedown pins. What do y'all think?

i have invented a new kind of full auto that is like burst and full auto at the same time and i'm looking for someone that own one to test if it would works. the modification of the gun concern only the buffer. i would prefer some kind of submachine gun. a big tube style gun with a end cap that could be change. i know i ask for the impossible but whatever. asking is better than nothing.

Can anybody help with figuring out the top latch? I have lots of pictures from a museum i visited to take measurements.

Just realizing right now it looks like a tec 9 lol. But it's not direct blowback and has much lower bore axis. I also realized that since the barrel is far and away from the hand, it wouldn't be problematic for this to be some sort of gas delayed pistol. But I like roller delayed because I prefer mechanical systems when it comes to suppression and everything. The gun is basically MP5 on top and AR on the bottom. The recoil system could be like it is in the picture and it's just a pulling spring like a trampoline for example. Or it could be wrapped around the bolt carrier like a regular mp5 and be compressed. The main problem I see here is pulling back the charging might be difficult due to spring tension. Also, you could easily have a flip out flux defense style stock or a telescoping one for a pdw concept. Could put a recoil buffer on the bolt as well. The grip might also be fairly fat but it's hard to say at this point. The magazine release will be just like an AR or a schnellfeurer. Slide release can be like a AR as well. Also, in terms of disassembly it can shotgun open like a AR. Also the ejection port will not be on top like most pistols and be placed much like in a rifle or MP5 and eject to the right. This should be a highly accurate pistol because the barrel and sights do not move at all. Much of this is just a minitiaturizred mp5/AR

A lot of the internals and its complexity and the ergonomics by modern standards are garbage. But this airsoft moc actually does show some of the promise. One of the neat things about the pistol is it doesn't take magazines in the grip, which gives it the ability to take very long, high capacity magazines. With minor tweaks to the original design, it could take an UZI magazine. However, I would want to do a lot more. Like having the grip positioned where it is the picture or even higher. And I would think it would be nice to make the barrel fixed and the bolt could use some sort of delaying mechanical system like roller delayed. Move the hammer spring and everything into the handle like a regular handgun. Make other necessary improvement ergonomics wise and I think it would be a pretty sweet gun. Fixed barrel and sights would make it very accurate and the design allows it to be retrofitted fairly easily to take larger calibers if desired. Would make for certainly an interesting competition gun or a PDW concept. The main problem with the general idea of the gun is its big and will likely be heavy unless you make it mostly from aluminum or alloy. Anyone else find this interesting or just plain stupid?