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Corrupt83
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Apr 2016
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#1
HPA M4 accuracy issue
22 November, 2016, 21:31
Evening all hoping someone can help me. I have a G&G M4 with a Inferno smp running @348 fps it also has as follows:-
PDI 6.08 inner barrel
Lonex hop up unit
S-hoped with a G&G green bucking
i use proball .28 bb's which use in other guns i have and they work great
The issue i have is no matter what i do every 5th-6th round bends badly to the left. I had the same issue before the new barrel or the s-hop but the issue is still the same.
Please could anyone advise me on something i may have missed.
Cheers
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#2
22 November, 2016, 22:14
Re: HPA M4 accuracy issue
Hi!
How fast in succession are your 5/6 shots?
Is shot 6/7 fine again if fired in same succession as the first 5/6?
Have you tried clocking all your shots through a chrono and seeing if the 5/6 shot has a big FPS variation as well as curve balling?
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Corrupt83
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#3
22 November, 2016, 22:50
Re: HPA M4 accuracy issue
Hi thanks for replying,
The fps seem to be stable and the rate of fire doesn't seem to matter either. I fire in single shot 5 rounds in 5 seconds or full auto the same thing happens.
some times its can be 2 or 3 shots that curve off but most of the time just the 1.
Im completely out of ideas.
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#4
22 November, 2016, 23:03
Re: HPA M4 accuracy issue
I was going to say possible regulator issue, but 5 shots in 5 secs is pretty slow and the reg' would have to be propper poo'd or have a poor inlet pressure to suffer that badly over 1 shot per second.
Otherwise id be looking at nozzle to bucking issue, either the bucking doesnt have quite tight enough lips to get perfect seal every time or the nozzle in the SMP isnt always travelling fully forward to seat in the bucking 100%
As you say it always curves in the same direction that would lead me to think that possibbly the nozzle is slightly off centre to the bucking and burping out the side if that makes sense??
- - - Updated - - -
I mean most HPA nozzle's are quite forcefully pushed forward compared to an AEG, which could if off centre mis-shape the bucking lips, giving a one sided 'burp'
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Corrupt83
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#5
22 November, 2016, 23:03
Re: HPA M4 accuracy issue
Thanks mate i think you have just confirmed my thoughts. Ill strip the SMP nozzle of tomorrow and see what the seal is with the bucking.
Thanks again for the advice
P.s any recommended bucking that you like to flat hop?
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#6
22 November, 2016, 23:05
Re: HPA M4 accuracy issue
No prob hope you fix it, do tell if you do
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Corrupt83
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#7
22 November, 2016, 23:07
Re: HPA M4 accuracy issue
Will do.
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Corrupt83
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#8
23 November, 2016, 20:42
Re: HPA M4 accuracy issue
I think i have found what is causing the issue. I think the lips on the bucking are too soft. I am now changing it to a Prometheus bucking (stuffer) but it is loose on the barrel even when i teflon tape it any suggestions?
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#9
23 November, 2016, 20:53
Re: HPA M4 accuracy issue
Thats odd, have you got a vernier? Most barrels are pretty close (actually usually slightly oversize) to 8.5mm.
I use a prommy black straight bucking on my HPA setup, take it the nozzle had good penetration?
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Corrupt83
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#10
23 November, 2016, 21:06
Re: HPA M4 accuracy issue
Do you find this a good bucking as all i can see is that they are soft. if any good ill order some from airlabs
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#11
23 November, 2016, 21:32
Re: HPA M4 accuracy issue
My bad, im running prommy straight purple in AEG and prommy red (hard) in my HPA, obv need to turn inside out and de mound/groove if R hopped.
But yes the red prommy is nice and tough, the purple and black prommy buckings are good but god they are fragile and PITA's to get out the hop unit!
- - - Updated - - -
Worth noting that the purple/black buckings from prometheus are very grabby and cling well to barrels, however the red one being harder n all is much looser.
Ive not had a PDI 6.08 my self, strange that the bucking is loose on it, new bucking was it?
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Corrupt83
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#12
23 November, 2016, 21:36
Re: HPA M4 accuracy issue
Cheers mate ill order a red one now. what do you run on your spa set up if you don't mind me asking
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#13
23 November, 2016, 21:58
Re: HPA M4 accuracy issue
Machined my own HPA 'engine', runs similar to a paintball setup with a 'bolt', 13Ci 3000 tank built into gun, SP1 reg, PDI sniper hop unit, fires 400fps as DMR @ 105psi on 6.06 450mm barrel.
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Corrupt83
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#14
23 November, 2016, 22:10
Re: HPA M4 accuracy issue
very nice. I've ordered 2 red bucking ill let you know the outcome thanks again for your help.
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paulg38
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#15
25 November, 2016, 08:36
Re: HPA M4 accuracy issue
I have 2 hpa guns smp and inferno gen 1.. best bucking I've used is the mad bull red shark, they have small barbs just inside the lips they keep bbs nice and tight
Sent from my SM-G930F using Tapatalk
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