custom build CQB question

[jimwu]

Hi All ! I would like to get some info from all of you here
Is regarding building an m4 CQB , but I don what is the really know what is the CQB requirement , mean the size of it ? like how long is the barrel and how long is the hand guard and etc ... ?
So can anyone give me a helping hand here
Thanks and have a nice day's


cheers

[BioRage]

Anything less then 10.5" would be considered "CQB"

Smallest I've seen is 4" - <madbull makes a set>

[devbro]

for CQB think VFC VR16 series

[Ricochet]

Overall barrel length is technically the only dynamic, not including added length for a suppressor. A standard M4 with a shorter than standard barrel is a CQB/CQC rifle, though there are several close-quarters variants such as the MK18.

[jimwu]

WOW ! That's a good information for me
thank you very much all
And how about the speed for it ?
What is the spring use for CQB ? mean m100 ... ?
And the barrel for high speed motor ... ?
Voltage of battery use ?
Gear ratio ?
Thanks

[BenG]

Well its alot more complicated then "we use such and such gears for CQB" it all depends on what you want to achieve.

For average CQB "speed" the "correct" or more comonly used word in airsoft is fps which stands for feet per second, for CQB typically 350fps or 325fps is the limit, rarer but not impossible to find are fields that allow 420 or 400 indoors, talk to your local field about fps limits.

As far as spring goes an m90 will give the typical CQB length gun an fps of about 300 ish fps an m100 around 340ish, a bad but easy way to estimate the power a spring will give you is to take the spring number and multiply it by 3.3 ex: m100 = 100x3.3=330 fps. This method of estimating is usually a bit low, but can vary wildly.

barrel length and motors have absolutely nothing to do with each other, barrel length depends on volume, but you would have to be really daft to base your barrel length on your volume, its much simpler to ajust the volume to the barrel by picking the correct cylinder to the volume of the inner barrel you have chosen, for a typical CQB build (230-280mm inner barrel) a type 1 cylinder is my go to, however I do tend to over volume my guns as I shoot heavy ammo (0.30g+) and the extra air, although ineffecient helps with that, esspecially at lower fps (<400). If you plan on shooting only .2g or .25g probably go with a type 2 cylinder.

As far as "high speed motor" those havent been used in forever, "modern" neodynium "balanced" motors offer plenty of speed in terms of churning out a high ROF. if your thinking "speed" in terms of trigger response, lots of motor RPM is not what you want, you want a low gear ratio and a torque motor, although with m90 and m100 springs, you dont really need any torque at all, and if you wanted trigger response id reqomend going with a heavy spring and short stroking it back down to an allowable fps. Essentially if you go with a high speed motor use a gear ratio between 13:1 and 18:1, if you go with a torque motor go with a 13:1 gear ratio or lower. As long as your motor is a neo motor you can really use whatever gears you want, and if I had more information on what you actually want to achieve I could tell you exact things.

As far as battery goes if dont have a mosfet you need to run 7.4v lipos, people who dont know very much about guns will tell you to use an 11.1v lipo but that would result in a lot of extra maintenance in the long run, as well as potentially dangerous situations. If you do get a mosfet, which I highly recommend you do, then it is "safe" to run 11.1v lipos without risk of destroying your trigger contacts, fusing them, or otherwise destroying the electrical system of your gun, and/or the battery. If your reading this and still use nicad nimh batteries, im going to be savage and say chuck them in the trash and by 7.4v lipos, your gun will run better, their smaller and much cheaper to replace, handle the cold better, and numerous other reasons. Never ever buy lipos from an airsoft retailer, your getting shafted.

Gears, see paragraph on motors.

[jimwu]

Originally Posted by BenG

Well its alot more complicated then "we use such and such gears for CQB" it all depends on what you want to achieve.

For average CQB "speed" the "correct" or more comonly used word in airsoft is fps which stands for feet per second, for CQB typically 350fps or 325fps is the limit, rarer but not impossible to find are fields that allow 420 or 400 indoors, talk to your local field about fps limits.

As far as spring goes an m90 will give the typical CQB length gun an fps of about 300 ish fps an m100 around 340ish, a bad but easy way to estimate the power a spring will give you is to take the spring number and multiply it by 3.3 ex: m100 = 100x3.3=330 fps. This method of estimating is usually a bit low, but can vary wildly.

barrel length and motors have absolutely nothing to do with each other, barrel length depends on volume, but you would have to be really daft to base your barrel length on your volume, its much simpler to ajust the volume to the barrel by picking the correct cylinder to the volume of the inner barrel you have chosen, for a typical CQB build (230-280mm inner barrel) a type 1 cylinder is my go to, however I do tend to over volume my guns as I shoot heavy ammo (0.30g+) and the extra air, although ineffecient helps with that, esspecially at lower fps (<400). If you plan on shooting only .2g or .25g probably go with a type 2 cylinder.

As far as "high speed motor" those havent been used in forever, "modern" neodynium "balanced" motors offer plenty of speed in terms of churning out a high ROF. if your thinking "speed" in terms of trigger response, lots of motor RPM is not what you want, you want a low gear ratio and a torque motor, although with m90 and m100 springs, you dont really need any torque at all, and if you wanted trigger response id reqomend going with a heavy spring and short stroking it back down to an allowable fps. Essentially if you go with a high speed motor use a gear ratio between 13:1 and 18:1, if you go with a torque motor go with a 13:1 gear ratio or lower. As long as your motor is a neo motor you can really use whatever gears you want, and if I had more information on what you actually want to achieve I could tell you exact things.

As far as battery goes if dont have a mosfet you need to run 7.4v lipos, people who dont know very much about guns will tell you to use an 11.1v lipo but that would result in a lot of extra maintenance in the long run, as well as potentially dangerous situations. If you do get a mosfet, which I highly recommend you do, then it is "safe" to run 11.1v lipos without risk of destroying your trigger contacts, fusing them, or otherwise destroying the electrical system of your gun, and/or the battery. If your reading this and still use nicad nimh batteries, im going to be savage and say chuck them in the trash and by 7.4v lipos, your gun will run better, their smaller and much cheaper to replace, handle the cold better, and numerous other reasons. Never ever buy lipos from an airsoft retailer, your getting shafted.

Gears, see paragraph on motors.

Wow Thanks you very much for the clear information , your help is really mean for me , thank you sir
I will use all of your info that you give for my study on how to custom my CQB m4 , thanks again


cheers

[BioRage]

Honestly; If your doing cqb, you might aswell get a Dye I4 Mask and a pistol with 6 mags.

As long as you run around like a speedsofter, you will do better then everyone most of the time~ #cqbnowadays

[jimwu]

Originally Posted by BioRage

Honestly; If your doing cqb, you might aswell get a Dye I4 Mask and a pistol with 6 mags.

As long as you run around like a speedsofter, you will do better then everyone most of the time~ #cqbnowadays

Hi ! Thanks for the advise , I also forget asking those question
Thank you very much ...


cheers

[SuperCriollo]

Don't get a paintball mask... Ughh. In my experience they are simply more bulky than a goggles plus mesh mask setup. PB masks also get hotter, and are less breathable