KJW M4

[wdahm519]

Can't wait, can't wait, can't wait, can't wait!!

 

By the way, I used my KJ M4 today in temps around 40-45 degrees, with light rain. The mags suffered slightly from cooldown, and a lot when firing rapidly, however I still shot far and pretty straight. Therefore, it seems the hop ups aren't being affected by any sort of "freezing" affect, where they would harden and/or become useless in cold conditions. This doesn't hold for true FREEZING temperatures, but its a good sign.

 

Also, the working forward assist is a LARGE AMOUNT OF SEX (appologies if "sex" is not forum tolerated... but its worth it in this case, because it is).

Edited October 25, 2009 by wdahm519

[SwatMP5man]

Ran my M4 again last night, seemed to work very well until about 10 o'clock when the mags started to vent halfway through, obviously way too cold for duster gas to work effectively. Also one issue i'm having a lot of with the mags is the bb's failing to feed upwards into the feed lips, and becoming lodged just below requiring me smacking the mags on the nearest wall to release them again, anybody else having this problem?

 

Internally, after about 3000 rounds no problems at all, again only sign of use is normal wear where the BCG is running along its rails, i have no signs of gouging or stress. The rubber cup in mine seems to be holding up, it feels more like soft plastic than a rubber, but i gave it a dose of silicon lube this morning.

 

Sean

[wdahm519]

Ran my M4 again last night, seemed to work very well until about 10 o'clock when the mags started to vent halfway through, obviously way too cold for duster gas to work effectively. Also one issue i'm having a lot of with the mags is the bb's failing to feed upwards into the feed lips, and becoming lodged just below requiring me smacking the mags on the nearest wall to release them again, anybody else having this problem?

 

Internally, after about 3000 rounds no problems at all, again only sign of use is normal wear where the BCG is running along its rails, i have no signs of gouging or stress. The rubber cup in mine seems to be holding up, it feels more like soft plastic than a rubber, but i gave it a dose of silicon lube this morning.

 

Sean

 

I had the same problem once in the cold with feeding. I just had to smack the mag hard and it worked. I think it gets so damn cold in there it just can't move upwards. Try lubing the mags too. I'm not too worried about this.

 

[t_hum]

Raven1 had this problem when he first got his gun. If he doesn't chime in here to give you his opinion on how to fix it just PM him, Im sure he has an answer for you.

[sacairsoftsn00py]

Raven1 also has one of the first 250 units produced. Wasn't the spring for the magazine replaced on those with a stiffer one as well?

 

The thing that I noticed about my mag is that the spring is pretty stiff. Stiff enough to where it pushes the bolt stop switch back to on when I want the bolt stop feature off. I could tstill turn the bolt stop feature off however. In time, the bolt stop switch on the mag will probably wear down rendering the switch unusable.

[wdahm519]

One quick game report:

 

I played a game yesterday and went through a few mags (this was the game in the 40's temperature (fahrenheit)). I inspected the cup ring today and noticed it had indeed torn, though even in the cold I was getting good gas consumption. It doesn't seem to affect things too much.

 

Nevertheless, t_hum, I want to be the first one to order your new piston (and FPS adjuster).

[Raven1]

KJW M4 Range Report

 

Sunday, October 25, 2009

 

0900 Hrs - 1300 Hrs

 

 

 

O-Ring Piston Testing - Project "Burn In"

 

26 Magazines Loaded Expended

 

Rapid Fire On Semi-Auto = 20 Mags

 

Fully Automatic Fire = 6 Mags

 

26-X Bolt Locked Back After Last Shot

 

 

 

Post Testing Inspection:

 

O-Ring Inspection revealed ZERO Wear

 

Piston Solidly Fastened (Using Blue Loc-Tite) Down To Carrier - ZERO Movement

 

 

 

Items Of Interest:

 

Item 1: Hop Up Exhibiting Consistent Hook on 2nd or 3rd BB - Moves To The Left - All Others Are Dead On.

 

Item 2: Magazine Damaged - Still Working As Expected - Pics To Follow

 

 

 

Total Mag Count = 326 Magazine Reloads (Full Mags Only DOES Not Include Partial Magazine Load Outs)

 

Total BB Count = 10,432

 

 

 

Well Dayum! So What I Found Out Is After 300 Magazines and Over 10,000 BBs I Must Replace A Hop Up!!!

 

I Don't Know Guys - Maybe I Got A Lemon???

[Raven1]

!!Magazine Issues!!

 

 

Be Advised There MAY Be Some Magazines Out there That Do NOT Have The Appropriate Spring Installed!

 

 

If you purchased / received a serialized gun and Asked for Warranty Parts Along with the New Metal Buffer, New Buffer Spring, You SHOULD Have Also Received Part # M14 Replacement Magazine Feed Spring.

 

This Is The Stronger Spring For Better Feeding But MOSTLY to Positively Actuate The Bolt Lock After Last BB Fired.

 

One Main Characteristic of the "Weaker" Magazine Feed Spring is BB Failing To Feed Up To / Through The Magazine Feed Lip - AGAIN - BBs Are Literally Floating Around In BB Channel With Zero Spring Pressure On Them.

 

One thing to note is my serialized gun arrived with the factory supplied magazine and it came equipped with the weak magazine spring. I also ordered a 2nd spare magazine and it Also Had the weaker spring. All of this was replaced free of charge by KJW, but it will cost you shipping.

 

The Easiest / Less Damage Inducing Method to Clear This Failure To Feed Is To Quickly Load Another 5 to 10 BBs and the Magazine Will Feed Properly. Beating or Hitting the Side of A Pressurized Vessel Is Generally A Bad Idea - The Only Way To Resolve The Issue Is To Have The Stronger Spring Installed

 

Again this ONLY Applies to the early production run of magazines, the later production magazine runs are already upgraded with the appropriate spring,,,

[sacairsoftsn00py]

Raven1-

 

What weight of BBs have you been running? While running propane, my KJ shoots darn consistent with .30g BBs. With .25g BBs some hook. With duster gas, .25g BBs shoot as consistent as when I use propane and .30g BBs. Theres very minimal wind out in the backyard. Also, I do know the difference between BB's hooking and BBs just curving from the wind.

 

[wdahm519]

Raven1-

 

What weight of BBs have you been running? While running propane, my KJ shoots darn consistent with .30g BBs. With .25g BBs some hook. With duster gas, .25g BBs shoot as consistent as when I use propane and .30g BBs. Theres very minimal wind out in the backyard. Also, I do know the difference between BB's hooking and BBs just curving from the wind.

 

I'm glad to hear 0.30's don't hook. I ran 0.25's when I took my KJ out and they were hooking consistently.

[sacairsoftsn00py]

Unfortunately, the fill in valve has an o-ring outside the nipple preventing effective transfer of duster gas into the mag. With duster gas and .25g bbs the shots do not hook at all.

 

I am guessing its got something to do with how heavy the weight is. Same reason .12g bbs go everywhere when used in an aeg. It simply wont cut through wind/air as effectively given the velocity.

 

*shrugs*

 

t_hums velocity reducers should help with controlling the shot consistency with .25g bbs.

Edited October 26, 2009 by sacairsoftsn00py

[Kai_Wolf]

I am currently using .28's and I dont have the hook effect going on.

[sacairsoftsn00py]

I have only tried Airsoft Elite .25g BBs with propane. I will try out Javelin .25g BBs and toytec .25g BBs tomorrow with propane. Temp will probably around 60 degrees.

[wdahm519]

I have only tried Airsoft Elite .25g BBs with propane. I will try out Javelin .25g BBs and toytec .25g BBs tomorrow with propane. Temp will probably around 60 degrees.

 

I too was using AE 0.25's, with propane, and had the same affect as SacAirsoftSn00py.

Edited October 27, 2009 by wdahm519

[sacairsoftsn00py]

Just a heads up, do take note of the feed ramp. Its the part that attaches to the upper receiver...the one that comes in contact with the rear part of the outer barrel.

 

I noticed that mine had some white stuff. I would guess that those bb's were getting scratched.

 

I already sanded part of the edge (the edge closest to the hop bucking) where the BBs were leaving residue on. I polished it as well. So far, I do not get any residue on that part anymore.

 

The hooking was observed even after I de-burred the feed ramp. At least I know that the bbs do not enter the hop chamber scratched (which could slowly wear down the hop bucking).

[Raven1]

Snoop Dogg!!

 

Bro, I've used "Echo 1" .25g BBs on Coleman Propane for the entire duration of the testing on the KJW M4!

 

The gun is designed / rated to be used on .25g hard beans and to be honest I just Never even thought about using anything else as I went out and bought several bags of the .25g BBs!

 

I preferred to use .28g beans on my AEG as those slung through the air for me the best.

 

Glad to know you have gone through the trouble of using .28g BBs as I'll think I'll switch back to that weight.

 

We'll see if the hooking effect stops at the weight.

 

Seriously Guys 10,000 hard beans through a hop up is Perfectly Acceptable - Don't Freak Out here!

[sacairsoftsn00py]

Kai is using them .28g BBs. I am using them KSC .30g BBs.

 

Generally, theres a 70 FPS drop when using .30g BBs in AEG compared to using .20g BBs. Those .25g BBs generally drop the fps by 30 copared to using .20g BBs. Theoretcally, we are still shooting around 440 fps with .25g BBs. Someone will have to chrono. LoL!

[Kai_Wolf]

If I remember correctly, my KJ was shooting 396 on .28's in 70-80 degree weather. I finally got to shoot it the other tday in warm (almost 90) weather and the recoil was even better than I expected and it seemed to shoot a bit hotter. Trying .30's seem to have slower results in reguards to fps, dramatically. I didnt chrono it, but you could see it.

[wdahm519]

If I remember correctly, my KJ was shooting 396 on .28's in 70-80 degree weather. I finally got to shoot it the other tday in warm (almost 90) weather and the recoil was even better than I expected and it seemed to shoot a bit hotter. Trying .30's seem to have slower results in reguards to fps, dramatically. I didnt chrono it, but you could see it.

 

What's the point of comparing FPS for bb weight? Its still carrying the same effective energy no matter if you use a 0.12 or a 0.48.

Edited October 27, 2009 by wdahm519

[wotty33]

Slightly off topic here but could anyone recomend a Sling Mount that would fit this gun? For a bungee 1 or 2 point sling. Would one designed for a SYSTEMA M4 PTW Series one work for example? There seem to be hundreds out there that all have slightly different attachments. Also does anyone know how you'd attach it? Take off the rear butt screw maybe?

Edited October 27, 2009 by wotty33

[Raven1]

Slightly off topic here but could anyone recomend a Sling Mount that would fit this gun? For a bungee 1 or 2 point sling. Would one designed for a SYSTEMA M4 PTW Series one work for example? There seem to be hundreds out there that all have slightly different attachments. Also does anyone know how you'd attach it? Take off the rear butt screw maybe?

 

Wotty33,

 

Not possible to use the standard receiver plate on the KJW M4 as it is a different design entirely.

 

If you want a single point of attachment you'll need to go with a mount that will 'Clamp' around the buffer tube.

 

Kai Wolf is using one, you might PM him and ask him how he likes the set up,,,

[sacairsoftsn00py]

What's the point of comparing FPS for bb weight? Its still carrying the same effective energy no matter if you use a 0.12 or a 0.48.

 

Comparing FPS for BB weight does nothing on paper. In practical use however it could mean a world.

Knowing how hard your gun shoots allows the user to select the weight appropriate to what their gun wold perform best on.

 

For example:

 

TM AEP's shoot 210-230 FPS with .20g BBs through them. If you use .48g BBs, your range will greatly suffer.

 

Tanaka M700's shoot up to 700 FPS with .20g BBs on a hot weather. If you use .12g BBs through it, you lose out a whole lot more on accuracy that what it actually puts out already.

 

By sharing FPS outputs, people could decide which weigh of BB's it is best to use for their gun.

[sacairsoftsn00py]

I just got around to shooting the M4 again. This time I used Javelin .25g BBs. No hooking problems with them.

 

From experience with them, they chronoed about 5-10 FPS lower than when I chrono Toytec .25g BBs which leads me to believe that they are heavier than those BBs.

 

Compared to Airsoft Elite .25g BBs, the Javelin .25g BBs do not sail high. That is, when the hop is perfectly set n the Javelin brand and I switch over to Airsoft Elite...the AE .25g BBs sail up some compared to a flatter trajectory with Javelin.

 

I am thinking that Javelin .25g BBs are heavier than both BBs which results in a more stable flight path. No hooking was observed through 3 magazine's worth of Javelin .25g BBs.

 

Still, KSC .30g BBs offered better precision and accuracy compared to the BBs mentioned above.

[phantomwarrior]

What's the point of comparing FPS for bb weight? Its still carrying the same effective energy no matter if you use a 0.12 or a 0.48.

 

Also, if you've read Noobie's sniper guide, you'd also know different bb's use energy differently.

 

I don't know how this would be used with a gas gun, but on a spring rifle it would go like this;

 

.2's = 500 fps = 3 joules

.25 = 470 fps = 3.1 joules

.3 = 450 fps = 3.4 joules

 

Those are made up numbers, but that's how snipers find the ideal weight. It's the bb with the most joules in their rifle, which means it is more than 500 fps on a .2 if there were no losses.

[wdahm519]

Also, if you've read Noobie's sniper guide, you'd also know different bb's use energy differently.

 

I don't know how this would be used with a gas gun, but on a spring rifle it would go like this;

 

.2's = 500 fps = 3 joules

.25 = 470 fps = 3.1 joules

.3 = 450 fps = 3.4 joules

 

Those are made up numbers, but that's how snipers find the ideal weight. It's the bb with the most joules in their rifle, which means it is more than 500 fps on a .2 if there were no losses.

 

I'm well aware of the different weights being equal to difference in rage due to drag (less for a heavy bb) or FPS (higher for a lighter bb), however if you're interested in knowing more about it I'd read this:

 

http://www.bbbastard.com/ATP/index.htm

 

It a very well documented, long "research" on bb flight path.

Edited October 27, 2009 by wdahm519