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[Help] MP5 Build

1465 Views 40 Replies 6 Participants Last post by  Leo Greer
Hello there good people, I've finally decided to build the sleeper MP5! My favorite weapon from childhood video games: Cs 1.6 and Cs Source, specificaly MP5-A5 (Collapsible buttstock, triangular plastic handguard). I've been wanting to get one since 2014. I would like to know which MP5-A5 is the latest and greatest on the market & which upgrades should I opt for.
I want max out range since it will be replacing my M4. Things to note is there's no fps or joule limit. Want to use 0.30bb to 0.36bb max. Can and will extend inner barrer with the supressor.
So ya just let me know good base to start upgrading, spring to cylinder volume to bb weight ratio to max out range and speed, looking for at least 60 meters but more the better. Thanks!

This is how I want it to look.
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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.
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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.
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.
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I’ll also point out that higher FPS can actually negatively affect accuracy (In certain scenarios). The BB is flying much faster, and experiences exponentially larger air resistance as it flies. Thus more propensity for deviation. The most accurate replica I’ve ever built only did 2j, which I feel is a very good sweet spot for AEG DMRs, since you can still be free with your choice of parts. Or at least, freer than when you go past an M130 spring.
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.
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The KWA 2GX shell that your Ronin probably has is known to be one of, if not the strongest shell available, albeit with some annoying proprietary elements.

You can buy direct from factory here in the USA and over in Britain, but shipping usually eats your savings, even on small items, since it’s usually at least $10 to ship to my location personally.
The MAXX chambers should be cheaper imo, especially seeing as they're $80 now. The window thing is just for a tracer unit,
I like the window so I can more easily see what the heck my nozzle is doing.
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I’ll go ahead and add, the Retroarms V2 shell has been known to have tolerance issues, most notably in the position of the bushing holes. It would be a really big deal with the amount of power you’re looking at. Maybe not all of the shell versions, but some for sure.

Retroarms Bushing Holes
According to the word of the tech who originally posted my reference thread, support blew him off, and other techs had the same issues… but as you point out—it’s airsoft, who knows!

And that’s according to this guy’s word. I don’t think he has a reason to lie about it, but people are crazy.
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At this point, I take other people’s suggestions seriously, but I don’t believe anything until I‘ve worked on it myself, and I don’t believe parts are good until I’ve used them.
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