I am giving serious consideration to dropping a Kythera HPA engine into my LDT MP5. Has anyone else done this? I am wondering what size nozzle to use? If the LDT MP5 spring magazines work well for this setup? I am over the electrical problems I have been having with this blaster and want to go completely battery free on this build. As always any advice will be gratefully accepted prior to jumping into this project.
While I can’t condone HPA ing anything, due to my prejudices against it, I can accept reasons why you might want to.
I thought that LDT spring mags still have a motor to run? Which would still need a battery?
If you still need a battery why not just get a jack and run a small battery with very little load on it?
As for the nozzle just use ldt rubber tip and make the length suit.
Again due to my prejudices I can’t offer any real help to install sorry.
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Cheers, HPA is not everyone’s cup of tea. Lol. These looked mechanical to me. They might have the electric cog at the top for feeding though. Has anyone tried these? If so how do they work?
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Yes they still run a mag feed motor, but being positioned at the top and being fed through spring pressure, they have a much more reliable feed rate than the old style mags.
Unfortunately I don’t have any personal experience with these, but have certainly heard good reviews about them.
Yeah will still be running a battery to power the mag and FCU, so HPA ain’t gonna overcome all of the electrical issues that can effect these components.
Actually i have a mate that’s is currently building a ldt MP5 witha kythra and a ugs stock
Still needs power to that mag, Setup wise, if you’ve made a HPA of anything LDT in a V2 gearbox it’ll be the same for the mp5. including nozzle.
kythera youll need a switch for the trigger and wire it up to the mag terminals.
Azraels if they ever release it are doing a powerless spring mag (but only for m4’s)
I do make nozzles and mp5 mag adaptors and have 3 mp5’s myself - sold a few, one of which is HPA.
Feel free to message me if you got any queries
Thanks for the advice team. I have decided to try the easy methods first . I will see if properly shimmed gears and correct motor engagement height fix my problems.
Hey Fabian, I’m infront of my mp5 here right now, I’m putting a Kythera in it, I did get a micro switch off x force but I’m not sure where to place it? Would you have any idea?
Btw your nozzle for my F2 in my m4 works amazingly, sorry I didn’t tell you earlier on the build but I am now getting a solid 295fps very very consistently which I am very pleased with and plan to use the same nozzle in my ldt mp5
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Ill see if i can track down how ive got my kythera setup.
Pretty much best place is where the most movement is. Could also have it action off the trigger. Mounting i drilled holes and threaded them. But superglue/araldite would be fine also. Theres not much force on the switch.
I went with a jaycar switch with a long extension that I bend until it actions just before the sear breaks… that way i can mag prime without firing
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Update on the build if anyone is interested, I know HPA isn’t everyone’s cup of tea, I’ve just had bad experiences with aeg
Anyways…
I got a different style switch and fitted it like this
I had some issues at first with the switch moving with the trigger and not switching the mag properly, easy fix though, just needed more epoxy,
After that I had to carve abit out of the switch to let the select fire pin go through the gearbox
After this I was happy apart from the look of the stock so I bought a MP5K ugs adapter and made it fit, and with that I had finished the build
I’ll upload later about tuning and performance of the gun
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Looks slick. Plenty of pic rail real estate 
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You have UGS! omg so awesome. Love the build!
just need yourself an adaptor and some of those fancy spring mags that azraels still hasnt released and youll have a fully battery free, line free HPA!
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I’ll have to get an adapter off you one day, I have pre ordered those mags, just waiting for the release, I can’t wait to try it out!!
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Looking awesome, what a dream set up.
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