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Building up my HK 416 A5

1674 Views 19 Replies 5 Participants Last post by  Guges Mk3
The gun that you have:

Your Budget:

I'm honestly going at this with an open wallet, but perhaps no more than $400?

Your Goals:
Rate of fire: Aiming for around 22~24 rps. Gun currently fires around 19 rps on full auto.
Velocity (FPS): Operation between <330 FPS w/ 0.2's (~1.0j, achieved with a cut M95 spring) and 405-ish FPS w/ 0.2's (1.51j; stock spring, used for outdoor)
Range: 50-125 ft
Accuracy: I'd like to be able to hit center mass of a man-sized target at around 100 ft reliably and consistently.

Your previous teching experience:
Limited to disassembling TM-design M9s and opening the ARES UMP45 V2 AEG and replacing the packing and barrel.

Willingness to learn to DIY and tech:

Willing to learn how to maintain it, but I'd rather it be built professionally as I don't trust myself with what I want on this one.

Your gameplan so far:
These are the parts I've considered so far.
* Gate Titan
* Tienly 30k (from Guges)
* SHS gears, but still not sure on what ratio to get. I believe the stock ones on the gun are 22.23:1 if my math for counting gears is not off. YouTube says 16.9:1.
* Replacing barrel to a Lambda 6.01 with rhop

Any outstanding conditions:
I live in the USA so sourcing parts from overseas retailers is not ideal but can be done if need be.

What Role/Type of Play You Will Be Doing/Playing:
CQB and Assault, so lots of semi and not a lot of full auto. [insert generic "T R I G G E R R E S P O N S E" here]

Other airsoft stuff you use in/on your gun:
Battery: Currently a Turnigy 3S 1000 mAh 20~40C lipo, but will be switching to the battery packs Guges stocks once they arrive.
BBs: Stuck to 0.2's for CQB. Outdoors, 0.28's or 0.32s (or whatever is recommended at my max range. 0.28's have just been what I had been using).

Actual question(?):
I'm looking into modifying my HK416A5. Planning on getting her built up to be more for outdoor use, but with the flexibility of being used indoors if need be in case a friend of mine wants to join in on the CQB fun (have the UMP45 as my primary for that). With this in mind, I've decided to go for a low-ish (22~ rps, is this still considered low?) stress build so I can swap springs and not have something blow up on me. With my limited tech experience, I'd like to minimize having to open her up to replace something.

Another thing I'm looking into improving is the reliability of the internals. VFC isn't quite known for having amazing internals and some of the stock parts can be dodgy, i.e. the gears, piston, and tappet plate if I recall correctly. The shimming, AoE, and whatnot will be done by a tech. I do intend to replace the built-in mosfet with a Titan and get rid of the in-line one she has going right now.

I'm looking for input on parts to grab/not grab so I can reach my goals above. If I'm misinformed about anything, please feel free to point me in the right direction! Thank you in advance.
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Seems pretty good from the looks of it. Assuming its the same box as the avalon, i would say new motor (which you have picked out already), Titan or other fet, and then a maybe on the piston/gears/ and bearings. I have had one set of vfc bearings let go on my first avalon after a pretty good amount of use (under spur gear failed).
After rebuilding it into a dsg, the spur gear lost a tooth after maybe 50k rounds. Swapped it for shs after that.
Would you recall what the stock gear ratio was of your Avalon? I am looking into bumping my RoF up a tad and wouldn't want to end up grabbing the same gear ratio as stock.

E/ Might as well radius the shell while its open
I'll put that in my notes!

also, some of the gen 2 avalons seem to have people run into broken spring guides. never had it happen to me, but might be worth picking up the replacement should it happen to you
I actually do have a spare incoming for this.. Think I read somewhere that the spring guide tabs were made of some sort of zinc alloy and would eventually break, so I went ahead and ordered the redesigned ones from RedWolf.

All AEG"s can hit man sized targets at 100', heck they can hit head at that distance reliably if you shoot .25g and above.
Looks like I got some tuning to do, or work on my aim. Prolly the latter.

I wouldn't go Lambda 6.01 and R-Hop unless you have an unlimited supply of the bbs of the same type in 5.95mm or less. If bore is too tight between bb and barrel it will reduce FPS and make your AEG less accurate.

Stay mid bore (~6.04mm) to allow you flexibility in bb types and keep it simple with a Maple leaf Matched set.
Gotcha. And to be clear, a Maple Leaf Matched set is a Maple Leaf barrel, tensioner, and Maple Leaf packing? Or just the latter two? I have been eyeing that MR hop 60 in your store for a bit. (Airsoft Atlanta used to be my go to, then you guys exposed them here lol)
But that 30k motor on a 3 cell lipo with stock gears would also hit about 25rps, it just may have more overspin with the indoor spring, but with that mosfet that's manageable.
Would be manageable with active braking right? Or can overspin be mitigated even without using active braking? I've been told that AB is really harsh on the motor.

As for barrels, the lambda 6.01 is a great barrel, but avoid their cheap coated steel ones, they are trash, go for the nicer stainless steel or go with a pdi 6.01

6.01 barrels are good, but not forgiving. It must be straight, good bbs must be used, and it must be cleaned often. Even then accuracy gains aren't guaranteed. But a fps boost is typically achieved due to the efficiency.

A 6.03 or 6.05 is more forgiving, and more accurate honestly, a laylax 6.03 barrel isn't a bad choice ever. I have a lapped one, and it is the best i have even after 6 years.
Considering what BBs I have on supply here, I'll likely stick to 6.03~6.05 then. Rather have some forgiveness, especially with the CQB field not wanting to have outside BBs. And their BBs aren't the best for sure.. I mean, come on, Lancer BBs?
I'm likely going to go with G&G for .25s and above, haven't steered me wrong yet despite the cost. That is good to know though.

Also, to come back to a previous question, overspin is manageable with active braking, right? Or can overspin be mitigated even without using active braking? I've been told that AB is really harsh on the motor.
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Thank you all for the responses so far. Digging further into the forums and considering the replies, I had a bit of an idea. My CQB field has a max limit of 25 RPS, one of the reasons why I have a low 20s RoF goal, while none of the outdoor fields I attend have a RoF limit.

I thought about grabbing 13.1 gears for increased rate of fire and semi-fire goodness. BUT! I'll use 11.1v LiPos for outdoor, and 7.4v LiPos for indoor. Using the HS5's (iirc) estimated RoF equation, rps = (X* V)/(TPA* Ratio) where:

X = a constant, 809.5135 in this case
V = voltage of the battery
TPA = 19, according to Guges' Tienly listing on eBay
Ratio = gear ratio. 13.65 if taking the 13.1s from SHS

We get around 23.10 rps on a 7.4v, and 34.65 rps on 11.1v. The 7.4v's RoF lands me just around my target RoF for indoor. I do understand the values may vary due to the difference in spring strength, and that TPA isn't a great measure for motors, so I may overshoot my target slightly. Would this actually work, or am I just crazy?
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You can get the same ROF by paring a HS motor with a standard ratio gearset on a 2S.

You saw the azimuth video right?
Yep! Saw that video. Still nuts that it was on a 2S.

And when people mention trigger response in SA. Do you have a basis for comparison?
I actually don't have a quantifiable basis for this. Just as a test, however, I did try both a 7.4v and a 11.1v on my UMP and 416A5 briefly and there's a slight difference in windup time (again, not quantified so we're going with feeling which is worst when trying to be scientific) and sound.

UMP - stock motor and gearbox, ASG M115 spring
7.4v windup sounds a tiny bit longer and whinier compared to 11.1v. SA trigger spam feels almost the same, both were able to keep up no problem.

416A5 - stock motor and gearbox, Action Army M95 spring
Like above, windup sounds just a bit longer and low pitch whinier compared to when using the 11.1v. SA trigger spam, the motor actually locked up on 7.4v but doesn't have the same problem with 11.1v
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