[Help] MP5 Build

Depends on how far you want the range to be out to. With some basic mods and few replacements I can make most guns hit 60. Above that it’s harder. For example I’m doing a build on an Arcturus NY06 CQB, which only has a 265mm barrel. The barrel was already good quality steel, and the hop unit was good, so all I did was replace the hop rubber with a PDI W-hold, and boom, 60 yards.

If I were you wanting to get 60 yards… get a variant with a standard or semi-standard V2 hop unit. If needed, replace with a G&G GR16 Rotary hop, which you can buy for $9 on Umbrella Armory right now. Use a basic fang style hop rubber like a Krytac, W-hold, or any of the others. They‘re easier to tune than other upgrade rubbers in my experience. Stabilize the barrel, etc, etc. Usual DMR mods.

I suggest you figure out the exact replica you want, and the range you’re trying to reach. You really don’t need insane power for a DMR, but if you’re asking for high FPS, we need to know how high exactly. 450 FPS (1.7j) is way different from 2.5j, 3j, etc.

I suggest staying away from the Maxx chamber. Pros: they work good. Cons: they only work good if you get it right, which can be really hard, some models don’t feed well at all, some models don’t work with certain mags, and they’re at least three times more expensive than a lot of other excellent options. Oh, and they’re picky about nozzle length.

Snappy semi isn’t too hard. ZCI HT and 13:1s. Even better, get whatever TPA you want from Chihai and do 13:1s. I’ve pulled up to M140 springs on 16 TPA/13:1, with very snappy semi. You’d probably want to use a torquier motor to avoid the motor heat issues I had with that build, but doing 22 or 24 TPA with 13:1 should pull a lot of springs.

On the flip side, I‘m working on a gun right now that will be using 18:1 gears and a 33K brushless. The brushless has so much torque that it acts like a 40K, and the trig response is insane. It’ll also pull absolutely whatever spring I want.

Gearbox shells are fun. It‘s hard to find one that fits your gun, aligns with your barrel group, and has the strength and compatibility to fit what you want.

Swollen.D said:

What do you mean ? Are you saying that there are MP5s that are M4 HopUp compatible ? And as for build I'd summerize it as compact DMR, with ocassional full auto on top of it. Want a M170 or M180 spring in there, that's like over 600fps measured with .2s but I will be blasting .36bbs.

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The Maxx is an M4 hop unit. I’m saying to find an HK rifle that you like that also takes M4 units. They’re much easier to work on and replace than a lot of the proprietary stuff out there for specific models.

For an M170-180 you’re looking at some serious work and investment. I hesitate to even try and recommend parts, since they’re almost guaranteed to break sooner rather than later, so there’s no real good suggestion here. At that point, on a full stroke setup, you’re breaking the “upgrade” V2 gearboxes, you’re breaking your piston, you’re shattering your piston head, you’re breaking your tappet plate, stuff like that. Oh, and very possibly your bushings as well. Spring guide too. Basically anything that even comes into contact with the spring’s energy upon release.

In summary, we can probably sniff out a parts list that‘ll at least fire it once or twice, but on that third shot there will be no guarantees. The most I‘ve ever used past 1000 rounds was an M160, and that was a terrible idea.

Just so y’all know, it’s not my intent to rag on Maxx. There’s nothing wrong with the parts themselves for the most part (certain batches of hop units have been known to have tolerance issues on the feed tubes, causing issues). As SS pointed out, tolerances are absolutely everywhere, so when parts have tight tolerances, they start to exclude other parts from the list of compatibles. For example, Prometheus makes a perfect TM spec hop unit that works great… but only if everything else is TM spec, which it’s almost never, unless you have a TM or a true G&P. Then they make their general spec unit, which works everywhere, mostly. You see what I mean?

The kicker for me is that I can take a hop unit that costs way less, and through some work I can make it just as good as the Maxx at hopping BBs without the compatibility issues. Or as many issues.

The features like BB retention and the clear window are cool though.

I’ll add that I actually use their nozzles, a cylinder head from them, and one of their hop units which functions great.