MP5 DMR project

[TacMaster]

I'm starting an MP5 based DMR project in the new year, but the first thing I need to do is find a way to extend my current MP5's barrel length without using one of those annoying iner-barrel-into-suppressor mods.

I'm thinking a little like this, but without the suppressor:

 

So, on the forum I found that photo, the OP said that the outer barrel extension was off a Star G36K. So I searched that up and the thread size was waay off that of my existing outer barrel's thread (Thread 1 in this post)- about 153mm. Thread 1 is about 12mm in diameter.

Thread 1:

 

The second thread is at the other end of the OB, where it meets Thread 3 which attaches it to the main body of the MP5. Thread 2 is about 17mm in diameter.

Thread 2:

 

Finally, Thread 3 is a shaped block of metal with a thread at one end and a hole all the way through for the inner barrel. It has a thread diameter of 16mm.

Thread 3:

 

So in essence I'm looking for an outer barrel with either a thread diameter of 120mm (to attach to Thread 1) or a diameter of 165mm ( same size as Thread 2, to attach to Thread 3)

 

Any help or suggestions are appreciated.

[Namaco]

Good luck but the 9mm magazine is not really helpful when it comes to making it look like DMR so its gonna be rather weird looking thing...

[TacMaster]

Most airsoft guns shoot 6mm BBs- why should it matter if I'm using an MP5 with 9mm size mags? Most real steel DMRs use 7.62mm and there are AR15 based DMRs in the airsoft world which don't get flak for their real world conterparts' caliber size.

[Namaco]

Most airsoft guns shoot 6mm BBs- why should it matter if I'm using an MP5 with 9mm size mags? Most real steel DMRs use 7.62mm and there are AR15 based DMRs in the airsoft world which don't get flak for their real world conterparts' caliber size.

The looks my friend! The looks!

 

Its like a potato trying to be a pumpkin... It will never be big and round like it.

[Moose87]

each to their own. i think it would be funny to have it. people woild be like what a noob for bringing an mp5 to woodland skirmish. then BOOM its raining accurate 450 fps on your ass. muhwhahaha

[Ian_Gere]

It'll have to wait until I get home to measure my SRC G36K OB, Tac.

[M_P]

people woild be like what a noob for bringing an mp5 to woodland skirmish.

To be honest those would only be the retarded people who don't realise barrel length means pretty much nothing.

Most airsoft guns shoot 6mm BBs- why should it matter if I'm using an MP5 with 9mm size mags? Most real steel DMRs use 7.62mm and there are AR15 based DMRs in the airsoft world which don't get flak for their real world conterparts' caliber size.

 

But there are real DMRs that use an AR-15 base, mk12 SPRs for example. It does look a bit odd with mp5 mags, maybe it'll look better with the short mp5k style ones.

[TacMaster]

I think he meant just the whole 9mm thing in general- but yeah, I'll be getting some stubby midcaps as part of the project.

[M_P]

He did specifically say the mag isn't helpful for DMR looks

[TacMaster]

It'll have to wait until I get home to measure my SRC G36K OB, Tac.

 

Alright, cheers Ian.

[Liam Porter]

Will your site allow you to use it if you're upping the FPS and locking to semi? I know some sites are really fussy about what classes as a DMR, some won't mind as long as it's semi only, some won't allow SMGs with a scope and a silencer to be classed as a DMR (which is essentially what this is, despite the slightly longer barrel), even if it is locked to semi, and some sites only allow DMRs if there is a real steel version of the rifle used as a DMR.

[TacMaster]

I've asked previously (been thinking about this for a long time lol) and they're fine with it if the gun's locked to semi. I asked if DMRs were constricted to real life DMR platforms and the site owner said it was fine no matter what I used as a base.

[Liam Porter]

Okay that's good then, you'll probably get looks of disgust from quite a few people though

 

About actually building it, I can't offer any help there, sorry.

 

What FPS are you looking to get, and what internal upgrades?

[TacMaster]

I'm thinking about trying to reach the 400-425FPS borderline. Atm I've been worrying more about the task of externals than internal upgrades, but if I can't find a non-suppressor styled barrel extension it won't be too much of a problem. I could always just tap an M4 OB for a 160/170mm thread instead, I have the tools available to me at college and my teacher will probably be happy to help me.

 

I'm a real noob when it comes to upgrades anyway, I've been reading this but the OP doesn't mention much about manufacturers or brands.

[M_P]

I've asked previously (been thinking about this for a long time lol) and they're fine with it if the gun's locked to semi. I asked if DMRs were constricted to real life DMR platforms and the site owner said it was fine no matter what I used as a base.

I thought you played at combat south?

[Ian_Gere]

ICS Turbo 3000 motor, SHS 13:1 Gears, SHS Delayer Chip, SHS M130 Spring, SHS Stainless Steel V2 Spring Guide w/ bearings, SHS Jet Air Seal Nozzle, PDI 6.05x390mm, PDI W-Hold Chamber Packing, 16AWG wire, 11.1V LiPo, Programmable MOSFET.

 

That should give you about 420FPS, good accuracy with 0.28's, and blistering trigger response.

[Liam Porter]

I'm thinking about trying to reach the 400-425FPS borderline. Atm I've been worrying more about the task of externals than internal upgrades, but if I can't find a non-suppressor styled barrel extension it won't be too much of a problem. I could always just tap an M4 OB for a 160/170mm thread instead, I have the tools available to me at college and my teacher will probably be happy to help me.

 

I'm a real noob when it comes to upgrades anyway, I've been reading this but the OP doesn't mention much about manufacturers or brands.

 

Okay, I'm planning a 500 FPS DMR. Read this guide a few times, shame it doesn't mention brands, but then it leaves it up to the individual and saves arguments in the comments, for example, I've had people recommend Lonex, SHS, Guarder and Prometheus parts, arguing with each other.

 

 

 

ICS Turbo 3000 motor, SHS 13:1 Gears, SHS Delayer Chip, SHS M130 Spring, SHS Stainless Steel V2 Spring Guide w/ bearings, SHS Jet Air Seal Nozzle, PDI 6.05x390mm, PDI W-Hold Chamber Packing, 16AWG wire, 11.1V LiPo, Programmable MOSFET.

 

That should give you about 420FPS, good accuracy with 0.28's, and blistering trigger response.

 

Seems like a decent list, nothing on piston and cylinder for good compression? Suppose that depends on the starting brand though. Can you recommend a MOSFET, that'll work with M14s?

[Russe11]

No way you could just attach a G3 front end? That would just be a stretched out MP5 instead of a long barrel sticking out the front.

 

I would personally start with an MP5SD and extend the barrel through the suppressor. MP5's with suppressors look daft but an MP5SD somehow looks good.

[Mack]

Heres some inspiration, Google HK94 for more

 

[Ian_Gere]

I'm really only just starting with MOSFETs. I've only personal experience with 3 and I wouldn't actually recommend any of them right at this moment, because the 1st Burst Wizard just died; my 2nd Burst Wizard King Kong is so complicated that it may be knackered or it may just be me, but it isn't working how I want; and the 3rd, a PicoSSR, which seemed to be the dog's may be responsible for my AKS-74U packing up - i've yet to have time to disassemble her to find out. The latter doesn't do anything other than regulate power anyway - it did do it bloody well while the gun was working though - noticeable increased trigger response and ROF with the same NiMh batteries.

 

Yeah, you're right, I forgot the piston & cylinder lol! An MP5 will need a new Cylinder. I don't believe it's money well spent to get a gucci one. An unported CYMA brass job will do the trick just as well as a Palsonite one, so long as you use Teflon Grease, which to my mind is a given.

 

I don't see much point in changing Cylinder Heads either - there isn't enough movement possible between the Cylinder and Head for a greased seal with only one O-Ring to be disturbed.

 

I'd go with the Magic Box Double O-Ring Piston Head, because, regardless of the nay-sayers, it totally must improve compression and reduce friction - a stock CYMA Piston Head comes with a very thin clear washer that fits where the POM Piston Head joins to the POM Piston - it doesn't make a perfect seal against the Cylinder on its own and during the compression phase it is behind the O-Ring, but nevertheless, if you add it to a gucci aluminium set up, it gives about 5FPS more. That said, for a DMR, there's a lot of sense in going for a Lees Precision Engineering Airbrake Piston Head, in which case a new Cylinder Head may be wise because they work better if the back of the Cylinder Head is completely flat.

 

Two schools of thought on the Piston:

- a POM one will be lighter and thus have a little less inertia, hence quieter and easier for the motor to move, which ought to be better for trigger response;

- an aluminium one will be stronger which, at higher pressures, may prevent flexing from causing additional friction on the Piston Guides of the Gearbox Shell;

 

- either way, with 120+ Springs 14 or 15 Steel Teeth is the way forward, but I don't know why some boxes use 14, some 15, or exactly what the point of 1/2 width Teeth is either - I mean, it must be weight, but surely it can only work in boxes that shim very close to the left hand side...anyone?

 

- anyway, an ICS drilled ali Piston ought to be the best of both worlds and comes with a full rack of steel Teeth.

[Ian_Gere]

Oh yeah, and re Lonex - I haven't tried one of their barrels yet but I'm not impressed with their metal AK hop unit or air nozzle. No better and possibly not as good as CYMA

[TacMaster]

I thought you played at combat south?

 

No mate, I spend most of my time at Ambush Adventures sites. I know a few marshals and one of the senior partners in AA from elsewhere. No mate's rates though!

 

ICS Turbo 3000 motor, SHS 13:1 Gears, SHS Delayer Chip, SHS M130 Spring, SHS Stainless Steel V2 Spring Guide w/ bearings, SHS Jet Air Seal Nozzle, PDI 6.05x390mm, PDI W-Hold Chamber Packing, 16AWG wire, 11.1V LiPo, Programmable MOSFET.

 

That should give you about 420FPS, good accuracy with 0.28's, and blistering trigger response.

 

Cheers Ian, nice save I'll just have to plan my spending in relation to those parts.

[Ian_Gere]

 

Cheers Ian, nice save I'll just have to plan my spending in relation to those parts.

Your MP5 is a CYMA, right? I'd leave getting a new motor until last, if so - they're designed for minimum 120 springs stock, so even though 13:1 gears & M130 spring is a jump in required torque, with the LiPo (oh yeah, get a 25C continuous 50C burst as minimum spec), 16AWG wiring, and a MOSFET, the additional current and the speed with which that current is made available ought to keep the stock CYMA motor up to the job - it's just who knows how long it will last once it is being worked hard?

[TacMaster]

It is a Cyma, yeah. Been used on semi for about 98% of it's life since it's auto is shite (something to do with the GB methinks, the battery's fine as I can draw out an awesome ROF with it in my M4. The MP5 works pretty well range wise anyway, so that kinda makes up for it) there shouldn't be any problems with it except slight weakening from use.

I actually took it out for the first time last week, with it connected up to an 8.4v battery with the GB and trigger mech in between. While I held it and pulled the trigger it was actually turning my hand with it's force!

 

edit: So far all those parts you suggested (excl. the ICS motor as we shall see how the stock holds out) come to a surprisingly achievable total of £118.42, without shipping I'll probably get majorly stung there though.

[Ian_Gere]

Yeah, shipping grrrrrrrrrrrrrrr...

 

The standard price from X-Fire is £15, and it might be worth emailing Bullseye Country Sports to see how much of the rest of it they can do, b/c they are pretty cool over shipping anyway and seemed pretty friendly when I harassed them over Madbull barrels a while back. Oh yeah, and they do 5% off for UKAPU members if you email 'em in advance to say so.

 

Otherwise, dualdealshop on fleabay are worth keeping an eye on.