Finishing up a dmr, and need parts advice.

[ratnest]

so I'm finishing up my dmr build, and need advice about parts.

the gun is m4 based, and the longest possible inner barrel i could hide in it is 560mm, I'm using a pre built king arms mech box with an m120 spring and a non ported cylinder,it is front wired. the hop up unit i bought is a madbull ultimate hop up unit, and an scs spacer.

main question is ideal barrel length/brand, hop up rubber, motor and battery. i prefer non lipo batteries, and was thinking of a peq box, there is no room in the stalk for any battery. also a reliably feeding 20 round style mag.

emphasis on accuracy and range. 380-400 max fps

[Spike]

1) Prometheus 6.03 tightbore barrel. Nothing else comes close to the quality
2) TM EG1000 motor (personal bias)
3) Firefly hop up rubber
4) If you don't want to run a rear wired lipo or full/crane stock, you're pretty much stuck with using a PEQ box.

[seabass]

Madbull tightbores are pretty great too. And I couldn't agree more on the firefly hop up. I still grin like an idiot every time I shoot my M4.

[phloudernow]

Madbull or Prometheus 6.01mm Tightbore - 6.01 since if its a DMR u might as well be shooting semi only
Systema Magnum Motor - High Torque motor for quick trigger response and maybe if u throwing in a stronger spring
I highly suggest you get a ASCU mosfet or a AWS Raptor Trigger FET for the active breaking, full cycle completion and DMR pre-cock mode
and id also go with Firefly Hopup Rubber also maybe the mad bull hop up too

[ding]

Is your DMR the VA(http://www.torontoairsoft.com/produc...d_product=1474) one? If so what was the stock gearbox? I'm about to build a DMR using the same body. Just curious what comes with it.

[ratnest]

as it stands, the gun is using a G&p zombie killer body, a magpull prs, madbull big dragon rail, g&p supresor, and a king arms gearbox it was bought entirely in parts, so i really have no idea what the va model has. although it is a nice rifle.

so everyone says a Prometheus barrel, but how long should i go with it? would the 550mm be to long?

[L473ncy]

- Prommy, PDI, or EdGI barrels are all top notch
- Firefly "W" hold bucking is the newest thing out there and from what Illusion says is really good
- Motor I'd take either a TM EG700 or Guarder Infinite Torque (this is just personal preference and their motors being pretty good value for the money)
- Battery I'd go with a "LiFePO4", not as good as a lipo in some circumstances but it's the most stable and forgiving battery in terms of taking abuse plus you can cycle it more than you can with a regular LiPo. Downsides being poor energy density and not a very popular chemistry (in both the airsoft and RC world) so it's hard to find batteries that will fit your gun. Maybe a thin "flat" triple nunchuck/butterfly battery in the rail system up front?
- As for mag, Magpul makes a "short" 20 round style mag (68 rd I think) as well as the G&P "Vietnam style" (110 rd.) mags if you want more of a traditional AR style mag.

[iKliiu]

If you want cheap and good, go Madbull barrel. If you want to spend more, go prometheus.

For hop up rubber, any will do. Just remove the internal mound in the bucking and you will get more range (flat hop).

Definitely get a ACM neodymium motor. They're roughly $20-30 and got amazing torque. If you want to spend some more, get a Lonex torque motor; that thing has crazy torque and barely heats up.

If you do get a ACM torque motor, I strongly suggest a high discharge LiPo. Those motors are power hungry and require a lot of start up energy. Make sure you have a mosfet if you are using a LiPo though.

[horto]

that PRS stock is sexy time. nice!

[Reckless]

+1 prommy barrel

for hop up .. I perfer modify 'accuracy' hop unit, ARS rubber with bump shaved, and SCS

.. as for length .. I beleive general consensus is a bore up kit is 'needed' for barrels over 509mm

if your target max is 400fps .. and you've got full kick ass seal with a M120 spring.. your gonna possibly already break that limit with a 509 6.03 prommy ... it's also strongly recommended that a full cylinder be used for anything over a 363mm

for me personally gearbox-barrel wise... full cylinder, ARS piston/cyl head, prom nozzle, M110 spring, at the moment I'm liking the Madbull half steel rack pistons, modify hop unit, ars rubber, scs , 509 6.03 prom barrel (end the barrel just inside the silencer, basically just clear the outter barrel) .. TM EG1000 motor, basic set of torque up gears (I personally haven't had much luck with helical and half tooth requiring Gear sets.. but many have.. nor have I really needed them) .. a raptor drop in trigger mosfet thing. and run a G&P PEQ with a 10.8v battery .. shim the hop and the inner barrel for as little to none movement as possible.. etc ..

mind you .. not much of the above is drop in, or plug and play ... infact it kinda rides the blurred line between DMR and AEG sniper rifle

if you take what you have, put the money/time into the barrel and the Hop rubber, make sure your FPS is consistant , run good bb's (aka BBbastard .3's or atleast .28's) ... run your inner barrel length to clear your outter barrel ... barrel quality means way more then barrel length.

[durak]

I dont know if it has been changed in the year or so I bought it, but the Madbull ultiamte hopup never worked right for me unless i had a madbull barrel and hopup rubber in it. somehow they managed to get it to only properly fit madbull products in it.

I suggest getting either a modify accurate hopup or a king arms hopup unit, promethius barrel, and a guarder clear hopup rubber.

for a motor if you can find one a G&P M140 is what ive had the best luck with, if you can't a G&P m160 or 180.

mags, MAG or PMAGS.

for a battery box
http://www.airsoftparts.ca/store2/in...oducts_id=1247

with http://www.airsoftparts.ca/store2/in...oducts_id=1648

[Reckless]

Originally Posted by durak

I suggest getting either a modify accurate hopup or a king arms hopup unit, promethius barrel, and a guarder clear hopup rubber.

unfortunately .. it appears the most recent guarder clears have gone tits up .. the feed lips deform and jam to hell and back ... and up around 400fps you'll kill one fast anyways.. those velocities (closing 400fps and higher) the ARS rubber is the way to go

[CJay]

Motor:
Systema magnum (but it's a basterd on yer gears)
Guarder infinite torque (awesome)

Hop unit:
Prometheus strike neo with te double airseal support tube feed.

Barrel:
Prometheus eg stainless steel 6.01mm tightbore

Hop bucking:
Systema mid durometer.

Stay away from madbull barrels and hop units. The barrels are anodized aluminium which means wear and tear will occur fast on ur dmr setup and lose accuracy. Hop units are a spin idea but hbe been proven to be very far off standard tm spec values.

I'd actually install a bore up kit with any barrel of 500mm or over or u get into negative pressure variables and u lost any hope of consistent fps and accuracy.

I'd also shoot for 430 fps so an m130-m140 spring ten cut the selector plate in te gearbox to limit itself to semi-only.

Using a MOSFET on this system is a terrible idea due to the heavier spring which means heavy current draw on the motor. Not to mention space limitations.

Battery options are extremely limited. As a dmr u want fast trigger response which is all about the battery motor combo. The motors I mentioned above will work ok in conjunction with a mini type battery but to be honest why waste ur time on a small an underpowered 9.6v mini. LeAves u with 2 real options. Simply go lipo eh uh means u can go smaller or do the best thing and go full stock and use a real mans battery.

Get urself a 9.6v 4400mAh large sub-C battery. Airsoft guns were never meant to run on mini batteries and on an outdoor gun it's not even worth it to run anything smaller. Larger capacity and physical size in a niMh battery means better performance and better trigger response. Don't waste time on an 8.4v as it lacks the oomph the really be snappy on the trigger.

I myself use nothing less than a 5000mah 11.1v 35c lipo. Although I do chew thru a few pistons every season but I get insane cycle speed and trigger response haha!

Seriously though ur battery option is a big part of a dmr so don't skimp. In this case size does count!!!!!!!!

[Kos-Mos]

Originally Posted by CJay

Using a MOSFET on this system is a terrible idea due to the heavier spring which means heavy current draw on the motor. Not to mention space limitations.

Why is that?

I have been using FETs in applications that require over 500A@36V and full stop burst... never was an issue.

Though most AEG mosfet for sale are quite on the cheap side...

You can easily setup a 600A FET setup (2x 320A N-FET + Hex driver) in the size a fuse takes. I did it on a G36 and it fitted where the fuse was. Not talking about electronic fire control, just the FET part. You could even add an aluminum plate on the FETs to cool them and bolt that inside the RIS.

Then again if programmed properly, the ECU should work as good... as long as the FETs used are strong enough.

[ThunderCactus]

My M249 shoots 1500rpm at 380 fps and my SW-COMP, which is much more sensitive than a simple mosfet switch, never overheats.

Prom 6.03 barrel at 509mm, that's about the max recommended length for regular cylinder
G&P M140 or M160 motor (M160 is one of the least expensive high power motors that's good quality)
firefly hop rubber
ARS piston head, provides ridiculously amazing seal
ARS cylinder head, provides great seal against air nozzle, which is extremely important for maintaining accuracy.

A simple mosfet is a great idea to maximize the power you get from NiMH batteries
A SW-COMP however is completely up to you, I personally think it's not needed in a semi only platform.

a 9.6v mini coupled with upgraded wiring, G&P M140 or M160 and a MOSFET is more than enough juice to give you a nice snappy trigger response.

And unless you do the insulation mod to the systema magnum motors, they're absolute fucking garbage. Honestly the worst stock motor you can buy, but it's really good once you insulate the end bell.

Wouldn't trust any guarder gears either, I've seen no less than 3 brand new sets get stripped in their first game. KA gears are fine, KA pistons are okay.
If you scrap your piston, get either a marui, system super core, or prometheus piston.
I run nothing but prom gears and pistons, they take a shitload of abuse, and they last a long long time. I'll usually get 2-3 seasons out of one before i decide to change it, and it's still not stripped.


Remember the most important thing in your setup is going to be achieving perfect compression. You want all the parts to mate together as well as possible. Any leak, especially between the hop rubber and air nozzle, will cause loses in accuracy.