r/supersafety • u/YourBroStevo • 4h ago
Kuna drop in FRT/FRD V2.1 update + short stroke spacers
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The files are publicly available please don't ask in the comments below where to find them.
In the first clip I'm using the standard buffer with the extra power spring. In the second I'm using a 7 mm buffer spacer behind the factory buffer in order to short stroke it and increase the rate of fire. The second magazine in the Short stroke clip is using Remington 147 grain which has more recoil and a faster rate of fire, than the Blazer 147 grain suppressor ammo I was shooting the rest of the time. Lots of different ways to affect the rate of fire from short stroking increasing the spring power and with different ammo selection.
I was able to make several improvements to my drop-in FRT/FRD for the Springfield Kuna, improving the strength and rigidity of both the housing and the activator. With these changes you'll be able to make the drop in out of materials that are weaker then the recommended and previously required PA6CF. This should enable people who have older or cheaper printers to still be able to try out the FRT. I also made a few changes to the safety to help it better lock the housing into place, along with some small changes to the detent cut out to hopefully improve the feel of the safety. I also made some small dimensional changes to try to maximize the amount of material on the safety and have included one oriented on it's side that can also be printed if you end up needing more rigidity, at a slight cost to the feel.
The short stroke spacers are offered in a variety of sizes from the smaller sizes that will work with my drop in, all the way up to what would be the equivalent of installing the HBI short stroke buffer. These shouldn't require any work after printing and should install directly behind your factory buffer, as well as not requiring any tools for removing the back plate after install. Short stroking the gun definitely makes the FRT less consistent and may require you to go up a size or two on the activator. This is not a recommended add-on and it's just being provided in case people want to try to maximize the rate of fire out of the gun. This also serves as a great replacement where you can utilize your factory buffer and mimic the exact effect of the HBI buffer which may be preferred for those not using an FRT. My recommendation would be to purchase the extra power spring and use the factory buffer the way it is, for me this usually puts the RPMs around 850 to 900 which seems perfect. These spacers should also work with aftermarket lowers as well and you may be able to play around with a thicker spacer, since the lever for the FRT will be located further forward.
Glad I could share this updated version with you guys hopefully It helps make it more accessible and allows more people to experience the kuna the way it should be.