Re: Lusa 9mm / HK MP5 compatibility
No problem, always happy to assist my Canadian neighbors. I'll try to answer what I know, at this point I could write a small dissertation on the Lusa.
I'll also add that I still had intermittent problems with the Lusa, even after replacing the trigger components. Out of sheer curiosity/desperation, I actually read an MP5 manual, it said if you are having trouble double firing check your firing pin spring. So I opened it up and sure enough the firing pin spring is extremely weak on the Lusa, it was also the reason (I think) that the pins are subject to breaking. Long story short, I went to a hardware store and bought a spring that was roughly 2-3 times as thick and I haven't had any problems since. The thing is a sewing machine now.
So here's the scoop on the Lusa:
Furniture wise nothing MP5/HK will work. I tried an MP5 stock and the Lusa receiver is too large. Even after grinding the stock there's not enough material to support it so that's an absolute no go. Hopefully I saved you $$$ because I gambled and lost on the that one. Also the front grip is completely proprietary, so no go on that one too. Essentially think of the trigger being HK with everything else being completely proprietary, I have examined this inside and out and everything from the barrel to the cocking tube is unique to Lusa.
Now in saying that, if I was absolutely set on having an adjustable or fixed stock, you have three options: You can screw or weld a folding stock to the butt plate after you pull that crappy adjustable stock out or you can buy an HK adapter like this: (
http://www.robertrtg.com/store/pc/K-...G-134p1870.htm) and screw or weld it to the butt plate. It wouldn't be a terrible amount of fabrication depending on just how bad you want a fixed HK buttstock. You could also buy a universal AR stock adapter and screw or weld that to the butt plate too. I've mulled over all these options but I decided against it. It's just not worth it to me.
Going back to the trigger, if I could do it again, I would NOT change out all the parts with HK. What I didn't realize at the time was that Lusa actually performed a trigger job at the factory using larger parts to create a crisper and shorter pull. I just assumed that was the problem since the guys who MADE Lusa's for a living and the owner of the company was telling me the trigger pack was bad. Both of them were essentially clueless about their own firearm and they were a partnership of TWO! Nice guys but geez.
As far as buying a trigger housing for it, you'll have no problem with the metal housings. The plastic navy ones probably won't work since they have extra material where a hole/buttstock needs to be. You might be able to dremel the extra material off...but I'm not confident it would work since you'd likely compromise the entire housing. Also you'd have to buy a new selector lever too since the metal one is too short to fit plastic. If you want to use a converted trigger housing it'll have to be clipped and pinned AND an additional hole needs to be drilled into it since the Lusa buttstock pin doesn't match the MP5 or G3. Bottom line: Yes, it's no problem with Metal MP5 Housings - all you have to do is drill a hole. G3 metal housings will also work provided you drill the extra hole and cut off the excess metal since the packs are longer. I would avoid plastic housings.
To be completely honest, I would advise you save your money and not buy too many HK parts for the Lusa. I know you want it MP5-esque (full disclosure that's why I bought mine) but the gun really isn't an HK except for the trigger. My recommendation is buy yourself a new firing pin spring at your nearest hardware store before you even fire it (this includes dry fire). That in my opinion is a must. Don't bother using a G3-MP5-UZI-etc. firing pin spring, they aren't compatible. The spring is totally proprietary.
A modification that is definitely worth doing is the hammer and hammer spring. The stock trigger uses a G3 hammer spring and I suspect this was due to them wanting the parts to work in full or semi auto. The problem is, G3 hammer springs are thicker and when you pull back the handle to #### it, it takes some effort. If you want it as light as a .22 bolt, switch the hammer spring out with an MP5. It won't affect reliability and it will lessen cocking the bolt back by several pounds.
The factory sights suck...like Mac 10-why'd-they-bother suck. I mounted a picatinny rail to the fake supressor and placed a red dot on it. After putting the red dot on, it's capable of splitting dandelions stems at >50 yards-not exaggerating. After doing that, it became the most accurate gun I own....which is weird saying and typing.
I should probably update my post since I know most of this info isn't on there. If you have any more questions let me know,