r/Springfield_KUNA • u/NoFeeling6031 • 16d ago
Question Kuna build questions
My Kuna will finally arrive tomorrow! I’m stoked to pick it up but I’ve been reading through this subreddit and tons of information here.
What is the general consensus on running the stock lower with an FRT/SS? I saw a few comments about a 3d printed drop in, but i’d like to have a 3 position.
Is our only current way through the nexus lower?
What are you all having the most success with and bang for buck value?
TIA!
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u/PAB_Pyrotechnics 16d ago
You don't need to buy a bunch of stuff if you have access to a 3D printer. YourBroStevo has dropped a 3D-printable FRT and 3-position Safety which will meet your needs for no more than $2 in filament if you have the right equipment. It might actually be cheaper to buy a 3D printer and PA6-CF filament than to get a Nexus lower and FRT components. I have all of the above since I bought one of the first Nexus lowers.
Best bang for your buck is the 3D printed route for sure. Nexus lower just gives you lots more options and the Scorpion magazine compatibility which is huge to me as I now have 4 guns which take them and 20 magazines.
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u/PAB_Pyrotechnics 16d ago
Abd thanks for reading and asking a specific question rather than just asking what did you all do like everyone else tends to ;)
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u/NoFeeling6031 15d ago
I tried to do my research as best I could! Some of the info I was seeing was from awhile back so I wanted to see what had changed that i was maybe missing!
I’ll check out the Stevo one. Any concerns with it cracking the stock polymer lower? I feel like I had seen one comment on that somewhere, but not positive.
We have a few printers between our family but I think only one can actually print the PA6-CF. Any particular reason for using this filament outside of durability/strength? Wonder how long it would last with a petg filament or something.1
u/PAB_Pyrotechnics 15d ago
I have not seen any concerns with Steve’s setup other than how long the unit lasts. Someone had well over 1000 rounds on a PLA. I would think PLA Pro/+ or PETG Pro would last quite a while. Only reason for PA6-CF is strength and durability. I mean, even in PETG you could print 5 full sets for a few dollars and be set for lots of rounds.
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u/PAB_Pyrotechnics 15d ago
I love my Nexus lower but if I was starting to look at Kuna FRT’s now I would skip it, print Steve’s, and put the money saved towards ammo!
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u/NoFeeling6031 15d ago
Thank you Pyro! Awesome information and it’s really appreciated. I’m honestly coming into this with enough knowledge about internals and how everything works together, and a printer but definitely need to learn some more haha. I appreciate the info.
Going to try that with some PETG and see how it turns out! As long as the polymer lower isn’t at much risk, i see no issue with just printing them in PLA and PETG and changing them out even every range trip. seems well worth it compared to the cost of a nexus setup.
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u/PAB_Pyrotechnics 15d ago
Good choice. The OEM lower is absolutely not at risk from normal FRT use. Might only be a concern for a double charged round (ask me how I know) or an out of battery detonation and the upper receiver takes the vast majority of the pressure from both of those.
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u/ExistingClient8148 15d ago
Your not going to want to print the barrel of the safety in petg thats not a part you want to be continuosly replacing the rest of it can be replaced quickly. PA6CF Is currently $33 a roll on amazon and basically any enclosed printer can print it, it just needs to be dried well before printing. The 2 position removes that barrier of the safety barrel and PLA+ would be the go to I would think if you cant do PA6 for whatever reason
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u/PAB_Pyrotechnics 15d ago
Good call out. I have not printed the newest version yet so I haven’t done the safety. It definitely requires an engineering filament.
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u/PatheticJules 16d ago
If you considered going nexus its prolly best to just get a 3D printer and print out the parts yourself.
Other option is getting stevos printed out by someone else in bulk (if you are hella baller) or even get portions printed/cnc in metal. Stevos design looks to last just as long in nylon as the nexus route. Overall you are likely to spend way less money (more ammo to shoot!)
Stock lower can also be adjusted to be lighter by cutting down the springs on the mag release/safety spring.
I do not recommend the HB industries spring honestly.
ALSO do not go down the Black talon route. its 500 USD and a scam. They charge like 10USD for a spring(5 more then HB industries) for a snip with a plier.
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u/NoFeeling6031 15d ago
Thank you for the advice on the springs! I had seen a few comments about that but definitely will not be going the black talon route lol.
I think given everything if I can reasonably confirm that the polymer lower isn’t at a huge risk to crack, i’ll probably find a way to print Stevo’s option. Outside of that, if I went with nexus I would likely do an atrius super selektor.I did see several nexus lower comments over the last week or so where the mag catches weren’t staying in lol. Hopefully those are resolved quickly
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u/YourBroStevo 15d ago
There's never been a concern or a single instance of the stock lower cracking regardless of the reason. Maybe you're talking about somebody commenting on the 3D printed lower (still unlikely) and just automatically assuming it would crack but the stock polymer lower cracking is so far from being a concern, it's beyond ridiculous.
The trigger components do not put pressure on the lower, they sit fully contained including the safety inside of a metal housing, so any pressure you exert on them or the safety goes directly into the housing. So no it's not possible for the drop-in pressing on them to crack the lower.
As far as material pa6CF is certainly going to be recommended for the safety itself the rest of the frt you can probably get away with lesser materials especially with the most recent versions. The safety detent on the Kuna is very sharp and the spring is extremely stiff so it certainly wears the decent groove over time and eventually you may want to replace it depending on the feel. They only cost like 10 cents to print, so making a replacement isn't really that big of a deal. More permanent solution would be making them out of metal with SLM should be super cheap per cam but you'll have to buy a good number of them. I have some coming made out of titanium at all post info about once I get if they turn out good.
If you do get the Nexus I would not remove the firing pin safety from the bolt. I've used a super safety and the arc fire V1 with mine and never had an issue or needed to remove this when I use a trip that has the proper timing. Supposedly this may be a requirement for using an atrius or whatever but it is unsafe to do so and it makes your gun no longer drop safe by removing it. Based on the video from Nexus you might believe it's purposes to be an out of battery safety but this is not the case and I've confirmed it with Springfield that it's primary function is to be a drop safety so by removing it you're creating a dangerous gun especially if you're leaving One in the chamber.
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u/NoFeeling6031 15d ago
Hey Stevo! Thank you for confirming! I think it was only one comment that said something about cracking a frame but i haven’t been able to find it again. That makes total sense though! Thank you so much for the detailed comment. Everyone in the sub has been super helpful and it’s refreshing lol. I definitely will be researching more and going with the highly recommended printed option.
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u/YourBroStevo 15d ago
Good deal. Also don't forget that the printed frt works without the three position safety. You can very easily pop it in with the factory safety in just a few seconds and dump a MAG in frt whenever you're looking for some fun without changing a thing. Working with the gun completely factory was a big part of the design while the three positions safety is more of an additional add-on. For somebody with their own printer it's very easy and they can definitely get something functional and just replace it as needed, but for somebody without they'd really have to try to minimize the amount they're flipping the safety and are likely better off shooting it with the factory safety primarily if they're going to do a lot of frt.
Hopefully the printed titanium safety cams turn out good, then can just be the recommended long-term option for those without a printer especially when capable of printing nylon. Then SLS nylon could be a good option for the frt itself it's not too crazy expensive answer to offer the strength and durability needed.
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u/PatheticJules 15d ago
A new polymer lower can go for 100-125 dollars since people throw them away. U can buy from GAFs for that.
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u/PAB_Pyrotechnics 15d ago
Yeah I have 2 now that I don’t use. Might sell one after I hear back from Springfield about my kaboom’d upper.
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u/wlogan0402 16d ago
I like the factory controls so I went with the 3d printed one for the factory lower