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M18 over hop


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#1 Italian13

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Posted 18 November 2010 - 01:03 PM

So after installing a G&P steel spring guide and 140% recoil spring (I doubt this is the issue), Action High-Flow valves and a Pro Arms 6.02 mm steel inner barrel, my BBs curve up no matter how much hop is applied when shot.  I've disassembled the barrel and Hop-Up assembly to make sure nothing was wrong and everything seemed normal.

I use Javelin .25g BBs and I use Propane w/ silicon added into the adapter, specifically this one: http://www.321airsof...PROP-ADAP-2.htm

The whole reason that I bought the 6.02 barrel was to try to get better accuracy, so it really irks me that all of my shots curve up.

I would greatly appreciate a solution!

Thanks,
     Italian13

EDIT: I can provide links to any of the parts if needed.

Edited by Italian13, 18 November 2010 - 05:13 PM.


#2 Spiggy

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Posted 18 November 2010 - 04:56 PM

Does your silicone come from a spray can?

#3 Italian13

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Posted 18 November 2010 - 04:59 PM

Nope. I use Madbull ultimate silicon: http://www.321airsof...ILICONE-OIL.htm

EDIT: Could it be the cold weather somehow hardening the bucking?

Edited by Italian13, 18 November 2010 - 05:11 PM.


#4 Spiggy

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Posted 19 November 2010 - 09:56 AM

have you replaced the ball bearing with any other ball bearing?

#5 Italian13

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Posted 19 November 2010 - 10:20 AM

Nope. Its the stock bearing.

Edited by Italian13, 19 November 2010 - 10:20 AM.


#6 Spiggy

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Posted 19 November 2010 - 01:32 PM

have you inspected/deburred the barrel prior to installation?  Some aftermarket barrels may have burrs or defects that would draw from accuracy.

#7 Italian13

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Posted 19 November 2010 - 02:55 PM

I have not done that, I just popped the barrel in. I'll check that next time I get to the gun.

Edited by Italian13, 19 November 2010 - 03:22 PM.


#8 Spiggy

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Posted 19 November 2010 - 03:59 PM

because the material is steel (and probably some form of a mild steel) a worn end mill can cause an off cut, forcing the burrs into the hopup slot.  If that's the case, you just need to de-burr the area.  If not, the burrs will press on the bb as it exits, causing this kind of astronomical hopup.

Careful, as it's possible to get so much hopup that the bb circles behind you and nips you in the bud. (Experience says this)  :thumbsup: Makes for an interesting story though.

#9 Italian13

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Posted 19 November 2010 - 04:10 PM

Sweet thanks. Now the only issue is, hoe exactly do I go about de-burring the hopup slot?

#10 Spiggy

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Posted 19 November 2010 - 04:19 PM

a tiny file, a steady hand, and a good bout of patience.

Please bear in mind, this is only one possibility in the long line of things that can go wrong.  considering the amount of aftermarket parts in your gun, anything can potentially lead to a problem.

#11 Italian13

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Posted 19 November 2010 - 04:25 PM

Patience I have, a file I can get, but a steady hand... I'll have to see... Anyways thanks for the help!

#12 Mikester619

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Posted 19 November 2010 - 04:43 PM

Use a small hand file. KWA M series hop up are very touchy. Little silicone on the hop bucking will cause inaccuracy bigtime. Are you adjusting the hop up with the hop tool. Make sure you check to see if the hop up is working. Disassemble the slide, remove the outer barrel, remove the inner barrel from the outer barrel and check to see if the hop hood(part #15 or part #96)swivels from clockwise to counterclockwise. Look down the barrel from the breech side to see if the hop ball is protruding from the hop bucking. I remembered reading your last post. You got that M18c from a trade so you did not get the hop tool. Also turn off the hop up counterclockwise and try shooting it again. I barely use hop in my M18c. Quarter turn on the hop up will cause the bb's to curve up and hit me in the arse

Edited by Mikester619, 19 November 2010 - 05:11 PM.


#13 Italian13

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Posted 22 November 2010 - 02:51 PM

Well I checked for burrs and there were none. The Hop-up hood swivels in both directions and I still have too much hop when turn all the was clock and counter-clockwise. Also the BBs start curving up ~ 100 feet out. What else could be going wrong?

#14 Mikester619

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Posted 22 November 2010 - 03:45 PM

What up Italian13, try to replace the hop bucking and hop ball(part#14,16). You might have a worn out or swollen bucking. My M18c had a swollen bucking. When i turned off the hop up, the bucking still produces a hop. All my M18C's,M26C's and M19 use a litte hop. Always clean the hop bucking and barrel before firing.

#15 Italian13

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Posted 22 November 2010 - 03:52 PM

I was actually thinking about that, haha. I'll order both the bucking and ball when I order a new PGC slide. I can't wait  :thumbsup:

The slide:

http://shop.ehobbyas...g18c-black.html

Also, theoretically if nothing works, could I just use heavier BBs to compensate for the Hop?

Edited by Italian13, 22 November 2010 - 04:11 PM.


#16 Mikester619

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Posted 22 November 2010 - 08:01 PM

Nice slide, I'm going to order the same PGC Metal slide Kit but in silver. You could also buy a KWA M34 inner barrel and a Shooter's Design rocket valve. I bought a Dee's custom KWA M34 6.01 tight bore barrel and an Airsoft Surgeon Rocket valve couple month ago. My M18c was shooting around 385-388FPS, temperature was 85-88 degrees F. After a month, the Airsoft Surgeon rocket valve broke in two pieces. Oh well my fault, i was shooting in full auto. The cool down of gases made the aluminum soft. Take care Also buy a Guarder enhance hammer spring 150% for the M18c just in case your stock hammer spring cannot pop the valve in hot weather.

#17 Italian13

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Posted 22 November 2010 - 08:17 PM

I may get the new inner barrel in 6.01 mm, but I also might keep the stock inner barrel so that it isn't visible, just for looks sake. When I ordered a trigger safty and new detent srping I saw the rocket valve and thought about, bnut I didn't have the money at the time, plus I tried to figure out how to dissassemble to loading nozle today to get to the rocket valve, but I couldn't figure it out and decided to put the prometheus (sp?) Bucking I also ordered into my TM G36k. I'll ad the hammer spring to my list of orders sometime in the spring, I'd rather keep some gas effecientcy (sp?) In the winter. It gets really cold here in Ohio.

Sorry for the spelling mistakes, I'm posting from my phone.

#18 Mikester619

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Posted 22 November 2010 - 09:20 PM

Sorry for the late reply, watching the San Diego Charger game. Go Chargers. That PGC slide that you ordered from ehobby comes with an extended outer barrel, it sticks out of the slide about 3/4 of an inch. When you install a KWA M34 barrel the inner barrel is covered. To disassemble the loading nozzle there is a pin (Part#26) has to be knocked out then the rocket valve(part#24 and spring(part#25) will pop out. (WARNING) put your thumb over the opening of the loading nozzle preventing the parts to fly out. Go over the Parts diagram of the KWA 18c before working on your pistol. Go to the KWA forums and look under the Library sections then find the M18c diagram. Good luck Ital.13 and have fun airsofting.

Edited by Mikester619, 22 November 2010 - 09:52 PM.


#19 Italian13

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Posted 23 November 2010 - 04:33 PM

I got the loading nozzle disassembled today... Granted I got a big  cut on my index finger... But anyways I'll look into the longer barrel. Thanks for all the help!




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