M4 - No range, double feeding and jamming

89db · August 2nd, 2012, 17:56

I am having this problem with my G&P M4. It keeps jamming in the hop up unit, from what I can see, the bb stuck is almost always visible from the magwell. Its pretty random but for example, it will fire 1 or 2 shots fine, then then fire at 10 foot, then double feed, then fire 10 foot, etc till it will jam.

Its a brand new custom gun, G&P body, G&P hop up unit. Madbull 6.03 thightbore, Lonex gearbox. everything seems to work flawlessly, I tested with 3 different mags, JG, King Arm & ACM and they all do the same. I have no problem with my other M4 that has the same thightbore.

Whats are your thought?

Styrak · August 2nd, 2012, 18:01

Something is probably wrong with your nozzle or hopup rubber.

However just for kicks, what does it do when you fire it upside down?

89db · August 2nd, 2012, 18:09

Good question! I ll try this tonight,

audi_bhoy · August 2nd, 2012, 18:18

My guess is that the hop-up rubber is sitting incorectly, but I could be wrong...

89db · August 2nd, 2012, 20:09

ok, so I did the upside down test, shot 20 bbs, no jam, 1 miss feed and I think at least 80% had good velocity (I tested it in my condo, so I cant say about the range and velocity but it seemed pretty fast/normal 350fps)...
What does it mean?

Kos-Mos · August 2nd, 2012, 21:03

Means it's not your magasine, probably the rubber that is torn or placed wrong.

Take your hop-up apart and rebuild it carefully.... and check for tears (they might be small, but allow the rubber to fold and jam a BB).

89db · August 2nd, 2012, 21:11

Fair enough! thanks for the help

angrypanda83 · August 3rd, 2012, 00:42

Had the same problem with my KA M4.

I replaced the hop up rubber... Same thing happened.

So I tried mid cap mags, and lubed up the first bb every mag... Seems to fire just fine now.

dodgetheram · August 3rd, 2012, 06:04

I just recently fixed a guys g&p at the field, he was having very scimilar issues. Turns out that small nub that gose between the bucking sleeve and the pressure arm was gone, so the bb was actually getting caught on the opening where the rubber protrudes through that small holde in the top of the hop up. All I had to use to fix it was a small peice of wire housing, but it worked great.

89db · August 3rd, 2012, 08:09

I might try what you did panda, I tried to spray a lot of silicone oil and it seems to help, maybe the bucking is dry or needs to be broken in.

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August 2nd, 2012, 17:56	#1
89db Trader rating Join Date: Jan 2012 Location: Toronto, Ontario	M4 - No range, double feeding and jamming I am having this problem with my G&P M4. It keeps jamming in the hop up unit, from what I can see, the bb stuck is almost always visible from the magwell. Its pretty random but for example, it will fire 1 or 2 shots fine, then then fire at 10 foot, then double feed, then fire 10 foot, etc till it will jam. Its a brand new custom gun, G&P body, G&P hop up unit. Madbull 6.03 thightbore, Lonex gearbox. everything seems to work flawlessly, I tested with 3 different mags, JG, King Arm & ACM and they all do the same. I have no problem with my other M4 that has the same thightbore. Whats are your thought? __________________

August 2nd, 2012, 18:01	#2
Styrak Trader rating Join Date: Jan 2007 Location: Saskatoon, SK	Something is probably wrong with your nozzle or hopup rubber. However just for kicks, what does it do when you fire it upside down? __________________ Airsoft Sales and Repair/Upgrade Services

August 2nd, 2012, 18:09	#3
89db Trader rating Join Date: Jan 2012 Location: Toronto, Ontario	Good question! I ll try this tonight, __________________

August 2nd, 2012, 18:18	#4
audi_bhoy Trader rating Join Date: Mar 2009 Location: Trois-Rivières	My guess is that the hop-up rubber is sitting incorectly, but I could be wrong...

August 2nd, 2012, 20:09	#5
89db Trader rating Join Date: Jan 2012 Location: Toronto, Ontario	ok, so I did the upside down test, shot 20 bbs, no jam, 1 miss feed and I think at least 80% had good velocity (I tested it in my condo, so I cant say about the range and velocity but it seemed pretty fast/normal 350fps)... What does it mean? __________________

August 2nd, 2012, 21:11	#7
89db Trader rating Join Date: Jan 2012 Location: Toronto, Ontario	Fair enough! thanks for the help __________________

August 3rd, 2012, 00:42	#8
angrypanda83 Trader rating Join Date: Jul 2012 Location: Trenton, Ontario	Had the same problem with my KA M4. I replaced the hop up rubber... Same thing happened. So I tried mid cap mags, and lubed up the first bb every mag... Seems to fire just fine now.

August 3rd, 2012, 06:04	#9
dodgetheram Trader rating Join Date: Mar 2012 Location: Ancater, Ontario	I just recently fixed a guys g&p at the field, he was having very scimilar issues. Turns out that small nub that gose between the bucking sleeve and the pressure arm was gone, so the bb was actually getting caught on the opening where the rubber protrudes through that small holde in the top of the hop up. All I had to use to fix it was a small peice of wire housing, but it worked great. __________________ G&P M4A1 KWA MK23 USSOCOM KWA TMP9 WE KAC PDW G&G MP5 SD6 TopTech WE 1911/MEU SOCOM

August 3rd, 2012, 08:09	#10
89db Trader rating Join Date: Jan 2012 Location: Toronto, Ontario	I might try what you did panda, I tried to spray a lot of silicone oil and it seems to help, maybe the bucking is dry or needs to be broken in. __________________

M4 - No range, double feeding and jamming

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