M4 barrel lenght and suction

Wow it has been a long winter!
I haven't been on in forever it feels like, but I have a couple of serious questions for experianced AEG users. I am interested in upgrading my m4 cqb. I believe it has a 300mm stock barrel, but I figure that the gearbox is the same as the standard m4a1, which has a 363mm barrel. I was curious as to what the maximum barrel lenght I could get. My mock suppresor is 155mm long, Therefore I would have the ability to put up to a 455mm barrel. I will be purchasing a polycarb, or metal hop up with the barrel, and a bucking that I need help finding from you guys. In conclusion, please explain to me how to avoid barrel suction, tell me the proper barrel lenght to get, I am looking at JBU 6.03 407mm, or JBU 6.03 440mm. Finally, I believe I could just upgrade my cylinder and head to avoid suction, please recommend one for the version 2 GB, and also the proper bucking that I will need. Also, what are your opinions on polycarbonate hopups, I heard that they match, or are better then metal hop ups.

Links,
JBU 440mm - http://www.airsoftpost.com/tight-bore-teflon-coated-aluminum-603mm-sniper-barrel-440mm-p-30156.html
JBU 407mm - http://www.airsoftpost.com/tight-bore-teflon-coated-aluminum-603mm-sniper-barrel-407mm-p-28165.html
Polycarb hop up - http://www.airsoftpost.com/element-polycarbonate-seal-hopup-chamber-series-airsoft-p-29635.html
Metal hop up - http://www.airsoftpost.com/full-metal-system-m16m4-series-p-25930.html
Bucking I was thinking about - http://www.airsoftpost.com/accuracy-rubber-highend-series-airsoft-guns-p-25958.html

I have done alot of research, but I still have those questions on the Suction, Hop up type, barrel lenght,cylinder upgrades(to avoid the suck), and the Bucking type.

Thank you.

First,

Unless you plan on going for a High Speed tuning set up, you don´t have to worry about barrel suck, it is not an issue. Barrel suck starts to occur on guns when you are getting into the 33-35 BB´s per second range, this is also influenced by the barrel length. If your gun is still in its standard form I would think you are shooting somewhere around the 14 to 20 BB´s per second, that is still a long way to go until back suction creates problems for you.

The metal hop-up will provide you with better results, but hooked up to a JBU inner barrel you will be disappointed with the results, JB Unicorn barrels just are not up to the hype, MadBull Black Pythons will give you better results for about the same money.

Hope this helps, Happy Tuning !!!

Yea, I was looking at the madbulls, But they did not have the 440mm lenght, I will be getting a madbull black python 407mm along with the metal hop up soon then. How about the bucking for the gun?

How would I be with a G and G 6.04, factory inner barrel.
by the way, it would be 407, or 443mm long, and my stock barrel lenght is 300, on a jg cqb r with no gb upgrades.

MadBull inner barrel,

What FPS is the gun shooting at ?? A soft rubber Buckling and nubbing will give you the best results up to the M120 level, after that a hard Rubber Buckling is needed.

As far as the length goes, you can always by one that is longer than what you need, cut it down and Crown it to the length that you need.

Well I could get the mad bull 455mm and that would go right to the very tip of my mock suppresor and still be well inside it so that no damage could possibly result. Pretty much I will have an m4 with an ak's barrel, except tb. I trust you about barrel suck, but I have read so many articles where they still say that they needed a type 0 cylinder because the volume of air being pushed was small then the volume of the barrel, therefore creating suction, but what you stated makes that theory disappear. I am most likely going to try to find a 407mm tb to be safe, unless you will garantee nothing like what I am stating can occur.

I know that you have pushed madbull on me now for the duration of this thread, but I am going to throw out my last company that you may like, I would be a systema 390mm 6.04 barrel.

P.S. I am shooting right around 390 fps accurately. After I make my accuracy upgrades, I am going to upgrade for power, with a matrix torque up motor, 8mm bearing set, ball bearing spring guide, high performance piston, reinforce cylinder head, polycarb piston head, and a torque up gear set, and either an m120, or m130 spring.

As you Upgrade for power, your ROF will drop, unless of course you upgrade your power supply.

Trust me about the Barrel Suck problem, we have a multitude of players in team using G3´s, CA, TM, SA, all running above the M130, 25 BB per Second, no barrel suck, some with standard cylinder sets, others with bore-up.

Systema is not one of my favorite companies, their motors are top, and with that, enough said.

ok I will go with the madbull, 365mm barrel, and I am ready to order. thanks for the help.

Glad to be of service