Does anyone know the average FPS that the M4 Open bolt kit produces? I cant seem to find that answer lol. Thanks alot

mine was shooting just over 400 but im not sure if there is a standard or not

I tried this and still had problems with accuracy. The hop-up control is better but still bb's hooked left and right randomly. It is an improvment but not enough because the gas delivery system I think is the real problem not only the hop-up. The bb's get split or cut and that probably is one reason they hook and never run straight.

The videos all on youtube show all the parts for the open bolt kit and none have a rubber spacer on the butt stock end of the spring retaining arm. I just got the open bult kit and I have a big rubber spacer that fits on the end of the spring retainer. This is probably the fix for the broken part 27 and 66.
I added and extra damper on the spring rod a 1/4inch thick neoprene grommet to give an extra buffer to the blow back.

The NPAS was easy to change the FPS which is something I miss.
So with an open bolt how do you change the FPS? Open bolt is about 395 to 400 now with just the kit.

With the open chamber you get an npas. They are like $15 + shipping and are the same ones used in tm pistols. It replaces the floating valve (I think that's the name). I found on the fly adjustments ate hard so I have a couple and just swap them out to the velocity I want

This is it http://www.ratech.com.tw/store/produ...?id_product=26 but note that depending on the rifle some modification to the nozzel may be necessary. Stock it works in the scar and pdw. M14 requires modification... Can't remember about the others

Most open bolts (at least my 3) shoot around 390-400fps. But this is entirely dependent on the length of the barrel

Thanks dude :cool:

I plan to buy an open bolt M16a1 and get myself Vietnam re-enactment combat gears and bdu.

Anyone can tell me their experiences with that rifle? Good or bad?

Any 20 rounds mags on the market for it?

Thanks :)

For those who are waiting for the Open Chamber CQB-R kit for your WE M4, UNCompany now has them.

Yea so does jugglez

There are viatnam style 20rd m4/m16 mags available for the we, was going to order a couple for my SCAR to try em out. They only come in open chber so if u have the awss system you'll have to find someone who's done a conversion and grab his mag tops/follower.

VN mags are super cheap. I've got 5 on order with AirsoftGlobal.

My CQBR OB shoots on average 430 fps with .2s. My bros hk416 OB shoots around 450 fps with .2s. This is for the factory stock OB and not the OB upgrade kit, if it makes a difference.

Has anyone noticed that part 66 for the OB is slightly different than the CB version? My part 66 has a screw and an additional metal piece attached to one of the prongs.

All my upgraded guns (upgraded to OB from awss) shoot round 400fps on .2g NBA which is fine for me as I don't need an noas then like I did before. G36c shoot stock at 390fps. I noticed on my scar that part #66 has that funny change with the conversion whereas converting my PDW didn't come with any parts for the trigger assembly... Found that kinda interesting

Anyone have this problem where the magazine won't stay locked in the magwell unless the Bolt Carrier is pulled or locked to the rear? My magazine just falls out.
When the Bolt Carrier is back and I insert a magazine, it goes in easy.

My solution is to hit the bottom if the mag harder until it locks