DMR Help

[efvarner2079]

I have been looking at parts to build a DMR from an old G&G M4 but I have little internal experience. I have tried to research these items but many people said one thing was good and then someone else said it was horrible. Below I have listed parts and wanted your opinions on the parts to know if it's a good deal or just a terrible product.
GEARBOX AND GEARBOX PARTS
-Modify Torus 8mm Gearbox
-Systema M150 Spring
-G&P M170 Devil Jet Motor
-Matrix 8mm Oilness Steel CNC Bushings
-JBU JA33 Half Teeth Aluminum Piston
-APS Chrome Full Cylinder (All Barrel Length)
-ASG CNC Aluminum Cylinder Head
-ASG Ultimate Ball Bearing Polycarb Silent Mushroom Piston Head
-SHS 32:1 Ultra High Torque Gear Set
*Any parts not listed will be stock parts in this build*
BATTERY AND MOSFET
-King Arms 11.1v 3300mAh 20C Lipo Large Battery
-Extreme-Fire Cheetah 2N MOSFET
CHARGER
-I haven't had much time to look for chargers. Suggestions would be greatly appreciated!

Thanks for any and all input!!!

[Stomper87]

Most of this seems like a waste of money... Basically, all you need is:
SHS High Torque Motor (long)
SHS Steel Piston
SHS (or really any other brand) Metal Piston Head
MOSFET (I suggest buying one from SteevoLS)
Your battery is fine, but theres better for cheaper
Sorbo Padding
XT60 or DEANS connectors
And if you want a little stronger, go with an m170 spring

This is close to the set up in my G&G M14, and its just fine. Also, G&G's M14 gearbox is pretty much indestructable...
Also, talk to Starfolder about a hop up. Your DMR will be usless without a good one!

[Star_folder]

Your parts are decent, and you'll have a decent DMR given that you put all your pieces and parts together, however, you can do this build cheaper.

Unless your gearbox is cracked or broken, you don't need to replace the shell. The stock one will be just fine. Just check to see what size the bushings are on the gearbox shell, and what material they are made of. If they are already steel bushings, then you don't need to get new ones. But if they are brass or bearings, then you should put the money into getting a new set.

The spring is fine. It should give you around 450fps with .25s.

That is a good motor, but it's an amp hog. I would suggest a Lonex A2 motor. It's a little cheaper, but is much more efficient than the G&P M170. The SHS motor that Stomper suggested is also a good one, It's basically a cheaper made G&P M170, but one of the cheapest *decent* motors on the market.

We went over the bushings just a moment ago. Doesn't matter who makes them, as long as they are steel and solid.

You don't want a full metal piston in your gun. It'll put WAY too much pressure on everything in your gearbox. SHS makes good pistons, Lonex makes good pistons.

Cylinders are like bushings, it's hard to mess them up. Steel is always a nice material.

I wouldn't go with the mushroom piston head, they are usually weak, and fall apart pretty quickly. They also don't silence a gun all that much, a very small amount, yes, but not very noticeably. I like Guarder compression parts, but Lonex makes good stuff too.

Ditch the torque gears, get some SHS 18:1 gears instead of the 32:1s. That's just a waste of power and will only slow down your trigger response.

I would check to make sure your stock air nozzle has an o-ring inside of it, if it doesn't, you'll need a new one. If you haven't caught on by now, Lonex is good, SHS is alright, Guarder is good. Prometheus is also good, but much more expensive than the other 3.

Good, heathy battery, but stomper is right again, you can find batteries like that for much cheaper than what you would pay for a King Arms battery.

Steevo makes good mosfets, but you are going to want to go with the Extreme-Fire in this case. The computerization of the mosfet will allow you to be able to set the gun to semi only, without having to do any extra modification to the gearbox. Using the mosfet to do this instead of the mechanical components of the gun is a way better option and is much more reliable.

XT60s are good, Deans are good. Don't forget the mods that need to be done to all guns, shimming the gears and correcting the AoE. Those are very important and are the difference of your gun lasting 500 shots, or 500,000.

[efvarner2079]

First, thank you Stomper and especially Star for using your time to help me with this. Sadly I can't use the stock gearbox because it's G&Gs blowback version and I had to drill out a screw because it stripped on me. And for this MOSFET would it stop the lipo before it goes under 3v per cell?

[Star_folder]

In G&G's blow back M4s, the upper receiver is built for the gearbox. You won't have a charging handle unless you replace the receiver, because the charging handle attaches to the gearbox shell.

And yes, the mosfet will protect your battery from over discharging. What it does, is when you plug the battery into the mosfet, it reads the voltage level and starts a countdown, of sorts. It labels that voltage at 100%. When the voltage drops to 85% of that charge, you'll feel a warning vibration when you pull the trigger, and the gun will keep shooting. Once the charge drops to 80%, the gun will completely shut off, and nothing will work. This will leave your cells at a very safe 3.3v per cell.

[efvarner2079]

Yeah, I have a n upper and lower receiver (so they will match) lined up. And thanks for the battery help (I've never been good at electrical things). For this build I was planning on getting one of your (Star) hop up mods. Which do you think would be best?

[Star_folder]

For a DMR, ER-hop. It's more efficient at lifting heavy rounds than an R-hop, and more durable than a flat hop. But any of my hop up mods will work for this.

[efvarner2079]

Ok, I'll PM you when I get all these parts in and working. And thanks again for all your time and help!!

[efvarner2079]

Well I've looked at piston heads some more and I haven't seen one good review on the gaurder one.....all have said its cracked or either shattered. Any other suggestions for a high FPS build?

[Star_folder]

Strange, I haven't broken one yet and they've been in all sorts of extreme set ups. After a quick search, the only bad review I found was from 2006. Also, I didn't note before, but you should get the polycarb one, not the aluminum one.

[efvarner2079]

Which one of these are you using:
Guarder Modefy Bore-Up Polycarbonate Piston Head
http://www.evike.com/product_info.php?c ... s_id=28203
OR
AIM / Guarder Polycarbonate Ventilation Piston Head For Airsoft AEG Guns
http://www.evike.com/product_info.php?c ... s_id=26510

[Stomper87]

First of all, bore up parts will not work in your gun, unless all of your compression parts are bore ups. Just get the second one you listed, it's one of the best Evike sells.

[Star_folder]

Yeah, I use the second one.

[efvarner2079]

Ok so I think I finally have all of what I'm getting figured out:
GEARBOX AND GEARBOX PARTS
-Modify Torus 8mm Gearbox (Have to get it )
-Systema M150 Spring
-Lonex A2 Infinite Torque-Up Motor
-Matrix 8mm Oilness Steel CNC Bushings
-Bravo Polycarbonate Piston with Metal Teeth
-APS Chrome Full Cylinder (All Barrel Length)
-ASG CNC Aluminum Cylinder Head
-AIM / Guarder Polycarbonate Ventilation Piston Head
-SHS 18:1 Standard Speed Steel Gear Set
BATTERY AND MOSFET
-ZIPPY Flightmax 3000mAh 3S1P 20C
-Extreme-Fire Cheetah 2N MOSFET
CHARGER
-Any suggestions? Are there any chargers that you guys like to use for Lipos?

One last question. Do you guys think I could run this setup with a M160(or maybe an M170) spring?

[Stomper87]

Here's the lipo charger I use: http://www.evike.com/product_info.php?c ... s_id=30777

It's cheap, simple to use, and I have never experienced any problems with it.
And if you were to get some sorbo padding:http://www.evike.com/product_info.php?c ... s_id=38402
Your gun should be able to use an m170 reliably. Heck I've got an m170 in a JG m4 with nothing changed but the piston and piston head!