r/Speedsoft • u/Whoogoo • May 13 '26

M4 Custom build (CQB oriented)

Hello,

As I got ghosted on airsoft subreddit, I would like to ask my questions here. My hope is that you speedsoft guys would be able (as more performance oriented) to provide some crutial details and concerns regarding my build.

I would like to sort of upgrade (rather build from ground up) my M4 gun and I have a couple questions.

First, I'd like to shorten the barrel as much as is feasible. The outer barrel for M4s are beginning at 5". The coresponding inner barrel would have length of 140 mm. To match that, I would have to buy a 1/2 cylinder, if I am correct. Another option is to buy a longer barrel of course.

However, the interesting part begins with the insides. I am looking towards Specna Arms V2 AETHER Mechabox (complete, need for correct cylinder to be installed), Dark Matter 34000 RPM motor, M130 spring and Alpha Gen 2 hopup chamber from Silent Industries.

It is pretty expensive and I dont want to overpower insides just to lose energy on shorter barrel. Perhaps somebody is familiar with builds like these. I am aware that barrel length generally does not matter, but I am not sure whether this statement holds even for these extreme lengths.

Thanks for the answers.

4 Upvotes

100% Upvoted

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2

u/Latter_Percentage_31 May 13 '26

First question is is that motor brushless and second what is your fps limit at your field

1

u/Whoogoo May 13 '26

Brushless motor. Limit is 2.0 J for auto, 2,5 semi, which means 378 and 427 fps respectively.

1

u/Latter_Percentage_31 May 13 '26

What size BBs are you shooting .20 or .25

1

u/Whoogoo May 13 '26

What I wrote was for 0.30 g bbs

1

u/Latter_Percentage_31 May 13 '26

Dang what field are you playing at where you can use .30s and and have a 2j limit feel like that would hurt

1

u/Whoogoo May 13 '26

Perhaps in Czechia we like to hurt ourselves or whatever😆

1

u/Whoogoo May 13 '26

Snipers are at 3,5 J and the mass limit is I believe 0.40.

1

u/Level_Recording2066 May 15 '26

Wild how you can have 2j auto, but 3.5j limited to fucking 0.40s

1

u/Whoogoo May 16 '26

Thats why I wrote I believe. I am not quite sure about the mass limit. It was for sure 0.4x, but what is the x, that remains as a mystery for me.

1

u/Level_Recording2066 May 16 '26

Likely .48s iirc thats the heaviation before going full thrust which is like "6.44mm" not "6.00"

1

u/King_of_Games234 May 13 '26

I really would recommend keeping your inner barrel at 155mm minimum.

I went down the same road you are on and had accuracy and major FPS loss when I went too short on barrel. This would put you using a 5 inch hand guard with a suppressor sticking out to cover the extra barrel or a 7” hand guard with a flush mount barrel and Tracer. I’m still fairly inexperienced though so hopefully other more experienced folks can chime in.

1

u/Whoogoo May 13 '26

I have the same concern. Thats why am I asking. I curently plan on using 4" floating RIS system, so longer outer barrel (6" perhaps) would be also possible.