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Project: KJW M700 ER-Hopped

9308 Views 32 Replies 11 Participants Last post by  OviOnePR
First, I don't know where to put this thread. Please move it!

So after much frustration with making a nub and attempting to perfect my M700's hop up, I decided that going a different route may be a better option. I recently caught wind from another member about ER-Hopping the gun would help greatly with accuracy and the such. After pricing everything and consulting HS5, I decided I am going to send my stuff to Skag to have him help me out with the ER-Hop. I know that there are a few members here with KJW M700s who are somewhat in need of a better hop-up system so I decided to venture into the unorthodox ways in hopes to find the best system for this rifle. And so we begin...
Last Tuesday I purchased the beginning parts:

First I purchased a PDI raven barrel. Why? Because I was sick of my Angel Custom barrel and I just so happened to have a $75 credit at Amped Airsoft from the white .43s I ordered. Also with that credit I purchased a Prometheus soft bucking.
Next I went to Air Rattle and got myself an IER-Hop patch. IER because I live in an area where the summer and winter are polar opposites and I plan to use the gun year round.
Next I went over to shape and ordered the Hunterseeker5 ER hop chamber for the M700. This is needed because of the extended hop up window, which requires a larger EM-Nub (which shall be provided by Skag). Shapeways will take around 10 days to complete the print, and they estimated May 29 that I will get my part.

So in short, heres what I ordered:
1) PDI Raven Barrel
2) Prometheus Purple AEG soft bucking
3) IER-Patch
4) HS5 Chamber for ER-Hop in KJW M700

Next portion is to get everything in, package it up, and send it to Skag to mill the barrel and install the patch.
I'll try to keep everyone updated on the build here. I remember the last thread about KJWs and ER-Hops was more of a question thread, so here I'll be actually updating you on the progress of a build. If all goes well, this thread will end with a shooting test, which will hopefully push the limits of the gun. Stay tuned!
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Alright so today we get a very simple update.

All parts have been shipped! Turns out Shapeways had prebuilt a model of the chamber I ordered so I don't have to wait a week for it to print. Yay!
Today the IER-Hop patch arrived. It's a nice blue color.

The PDI barrel and Prometheus bucking have been transferred to my local Post Office. If I get home from school tomorrow and the package is still not there, I'll just drive over and pick it up.
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New update…

PDI Raven Barrel and Prometheus Soft Bucking arrived today.
Turns out that Shapeways had a model of the chamber already printed. So instead of arriving May 30, it'll come to my doorstep tomorrow.

With that said, tomorrow I will receive a quote from Skag for his services. I may have this little project done by next week.
Sorry for being so lazy in this thread… Seems like no one is interested. But a promise is a promise and I will update once again.

Since the last update, I got the shapeways chamber. The chamber for some reason did not come with the C-Clip, which is very necessary for keeping the barrel in the chamber. Shapeways sent me a whole new chamber (arrived yesterday), which is why I delayed until now for the update.
With everything here, I sent the package to Tony Zito, the HS5 certified ER-Hop technician.
Things should arrive to him on Thursday this week, hopefully I'll have everything back before my local skirmish on the 21st. If I don't, that whole hide goes to waste. I asked Tony to use priority mail and not delay with the project.
I also sent him my outer barrel so he can even the cut on it.
Photos later
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I am interested bobcat. Just because I don't post does not mean no one is interested.
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I am in the same boat as Plazma on this one. I don't own an M700, or any gas rifle for that matter, but I am always interested in learning how to do different things with any rifle.
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Looks cool! I was thinking about picking up a KJW M700 in the next few months, so this will be quite handy.
I am thinking of picking up a M700 in the future. So learning how to do and what to do to get the best performance is worth it in my book. So keep doing what you are doing!
Ok, thanks guys.
Maybe at some point when everything is done I'll make a final "build thread" so I can tie all of the previous project threads together.
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A "final build thread" would be greatly appreciated!
Well, I am thoroughly disappointed.

Yesterday, my maximum range was 200 feet with a .43g bb, shooting in the vicinity of 450 FPS. Not sure why 200 feet was as far as it was going, but I continued to shoot.
Those shots would over hop, under hop, then rarely curve to the left.
Near the end of the day bbs stopped going 200 feet. That became a pipe dream, because now the gun was shooting a mere 10 feet. Yes, 10 feet.
I hand tested the barrel seal and found that the barrel could freely move within the bucking because the chamber only holds it in via friction, what fun. I pushed the barrel closer to the chamber, it became all sealed up.
Shot it again, first shot flies…11 feet! QUE BUENO! The next few shots, well, some didn't even come out the barrel. It became obvious that I was losing massive amounts of my CO2 somewhere between the barrel, patch, bucking, chamber, nozzle, bolt, and magazine.
I began my autopsy in that order, reversed. I noticed to issues with the magazine, bolt, or the nozzle when hand tested. My investigation continued onto the chamber. The first thing I notice is a small piece of rubber sticking up from the bottom, the first sign of a ruptured bucking. I decide to bypass the surgical removal of the chamber and went straight to the bucking and barrel. My diagnosis concludes as so: The barrel shows that the ER-patch had torn in half and the bucking was torn near the nozzle end.
Not only was the patch torn in half, but it looked like a dog ate it, crapped it out in the mud and let it sit while getting run over by ATVs. The patch, needless to say, was in very bad condition. What happened? I have no clue.
Tony Zito and I exchanged several emails prior to the findings, starting with very easy suggestions, like barrel spacers. Yeah, those will increase the range by 190 feet. Easily. He eventually told me just to check the bucking and stuff and report back, I had already done that when I received the email, I'm anyone looking to fix a rifle would have done that anyway.

All in all, I am VERY DISAPPOINTED with everything. Lets begin with this: I spent more than $200 on the project. Thats $50 in parts and $160 in services from Tony Zito. On the second day of shooting, everything explodes. I'm telling you, if a KJW M700 had an appendix, it clearly ruptured. What does the surgeon do when the appendix has already ruptured? They clean it up and hope the patient lives. That is what I am going to do.
I'll clear this up with Tony and the mess from my gun, and hope that the gun lives.
Thanks for following this project, to whomever actually did, it's over now. I do NOT recommend this. At All.

So what am I going to do, I'm out a good amount of money and I've got a small skirmish tomorrow. I replaced the internals with everything old. Angel Custom barrel, stock rubber, stock chamber, stock nub. Performed better.
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Hmm that is pretty discouraging. Could you post some pics up of all the components and broken bits? I want to rule out a botched install, bad product, or if it really is a bad idea.

Reason I bring it up is I ordered some stuff from shapeway not long ago and it was off spec slightly.
To tell you the truth, I have no clue what it was. Even when I don't have experience, I can usually come up with a possible solution other than what you mentioned, but this time I am drawing a blank.
I can give you this, though: Tony did say that the chamber was a tight fit, but I don't think it would have been tight enough to tear a patch after 100 shots.
The ER-hop filing job seems pretty good, though it does look like Tony did a slight downward slope towards the end of the barrel on the window.
I'll post pictures in a bit
Thanks for posting your findings bobcat, sorry it went so bad. Are you going to try too fix it or are you going to continue using the old setup?
When you said the fps is 450, is that with the .43s or with .20s?

EDIT: Actually I think I may have an idea as to why it died. If your FPS is indeed with the .43s. then perhaps this occurred. With what you said the bucking seemed like it was tapered in the front then perhaps this caused a pinch jam, which resulted in a blow out of your patch and bucking. With the pressure being so high it forced the bb out of the jam. Which as you say the bucking is tapered down slightly into the barrel in the front makes sense. This theory would be a direct cause of a botched install.

Keep in mind this is Plazmaburn theory. I have been known to be horribly wrong from time to time.
I did a chamber conversion on my G96 to an M700 and had similar results with both chambers. The rifle was tuned to 4J (450fps w/ 0.43g) and ended up tearing apart a bucking fairly quickly with both forms. I have plenty of barrels and chambers to experiment with as a result.

I'm working on another option similar to a J-hop, but with added special sauce. Might be a direction to take your M700 if it works.
Plaz, that seems like a relatively good theory, it makes some logical sense.
The FPS was around 450 using a .43g bb. I don't personally own a chronograph or live near one so I am using a rough estimate based on my pressure gauge, which is of course broken, that showed 200 PSI (it shows roughly 70 PSI greater than true reading)

The IER-Hop was designed for high speed, heavy weight bbs, right?
Also, when I took out the barrel, the patch looked, in no way, glued in place. It freely fell out of the barrel.
I emailed Tony Zito earlier today with no avail as well

Might be a direction to take your M700 if it works.
Keep me posted on that. I'm really close to calling it quits with my KJW M700, I've spent a lot of time and money, not to mention the blood, sweat, and tears (quite literally) I've put into this gun (and cleaned off of the gun, too) I mean, I think its hit around $300 in just the hop-up, I still can't find a solution!

Plazmaburn: I guess it's safe to say, I'm counting on you for the nub design. I've tried a lot of things, and still nothing.

This much work and little play makes this bobcat sad.

@desertsniper, I am currently using the stock setup as a place holder. Skirmish tomorrow, lets see how it goes. Terribly, well, sucks for me. I've run out of ideas with this rifle.
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When finish one of the prototypes, I will send you some rhop tubing with it, or you can send me your barrel and I will install it.
Tony seems to agree to redo the install, he's baffled about the situation. He said he's never seen something that beat up.
Again, this is from 140 PSI with .43 bbs, on a 455mm barrel.


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