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April 24th, 2015, 17:06 | #1 |
VFC Mark 12 FPS loss after spring change
I changed the spring of my VFC Mark 12 because I had 415-410 FPS. I switched to a brand new modify S100+ spring, and now I have 295-300 FPS.
Upgrades: -madbull 6.03 509mm -SHS CNC cylinder head (new) -SHS nozzle (new) -Metal hop up chamber -S100+ modify spring -Loonex rubber Things I have tried : Change back to old spring = same FPS Change for an other spring = same FPS Bought a new set of nozzle + cylinder head = same FPS The ''kiss'' between the nozzle and the hop up rubber is perfectly sealed Removed old grease and cleaned it, but back back new grease (just enough, not too much) = same FPS Checked FPS with an other gun = the problem is not the chrono Put back old hop up chamber and stock barrel = same FPS Did the compression test : Cylinder only = perfect Extended nozzle = perfect until I push very hard, I can hear a very very small leak. Did the ''paper check'' (gun placed upside down, small piece of paper over the BB hole in the hop up chamber) = barely moves Added Teflon tape to the front of the hop up chamber = same FPS My rubber sits tightly in the hop up chamber, I need to grease it in order to put it in Changed the hop-up rubber with an new one = same FPS BBs used : madbull 0.25g Bio = 300 fps Canadian tire 0.20g = 280-290 fps Used an other magazine = same FPS Remove the brass ring on the barrel = same FPS Ive checked many posts on many forums, and I tried everything. Nothings works. I am seriously thinking to go to the local church and ask a priest to exorcise my airsoft gun. If you have any suggestions or any tests to perform it would be very appreciated. Thanks and sorry for bad english.
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April 24th, 2015, 17:19 | #2 |
formerly steyr
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Is the cylinder ported? Did you lube the nozzle/cylinder head interface? You might need to trim the tappet plate spring and maybe trim the tappet plate fin down a little To ensure the nozzle is seating properly, the SHS ones can be kind of tight and it may not be returning fast enough.
Or maybe your chrono has low batteries. |
April 24th, 2015, 20:48 | #3 | |
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April 24th, 2015, 21:02 | #4 |
Not Eye Safe, Pretty Boy Maximus on the field take his picture!
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Stupid question: Did you put the cylinder in backwards?
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April 24th, 2015, 23:41 | #5 |
"bb bukakke" KING!
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^^ what he said.
though for a mk12 cylinder going in backwards you'd be getting in the 100s fps.. though you should check anyways.
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I futz with V2s, V3s and V6s. I could be wrong... but probably, most likely not, as far as I know. |
April 25th, 2015, 03:50 | #6 |
formerly steyr
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You are very under volumed for your barrel length. You need a non ported cylinder.
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April 25th, 2015, 07:24 | #7 |
Im sorry guys, I forgot the "not" in my last post, my cylinder is NOT ported.
But once I tried to put it backward, didnt made any difference. I have some wear in it. I can see where the piston stops inside it. But since I have a perfect compression I thought that my cylinder is ok.
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April 25th, 2015, 20:24 | #8 |
"bb bukakke" KING!
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if compression components are good, the barrel group has good compression, have you done the tissue test? put the gun together, upsidedown, block the barrel and put some tissue in the magwell over the hopup feed. Shoot the gun... if the tissue flies out then your hopup/nozzle interface is incorrect.
You can fuck this up by overtightening the grip screws or the buffer tube screw (vfcs shouldn't have this issue as the buffer screw doesn't go into the gearbox) Missing body pins can cause misalignment, maybe the gearbox isn't sitting completely lined up with the hop when you put it in the receiver.
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I futz with V2s, V3s and V6s. I could be wrong... but probably, most likely not, as far as I know. |
April 25th, 2015, 20:30 | #9 |
Stupid question: is the hop-up disengaged/turned off all the way?
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April 27th, 2015, 13:34 | #10 | ||
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Thanks
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April 27th, 2015, 13:48 | #11 |
To be honest, it sounds like your fps is pretty consistent and you've passed all the test so you could just have normal performance with an M100 spring at 300 fps. Maybe it's a lemon spring lol? Try it with an M110 and see if it helps. Mayhaps the seller accidentally switched the Modify M100 with an M90 spring?
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April 27th, 2015, 13:59 | #12 | |
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April 27th, 2015, 14:23 | #13 |
I just tried a stock spring who is supposed to shoot around 420 FPS, I had 315 FPS... still 15 FPS increase !
And I just found an other problem : Mid cap wont feed well, only high caps. The problem is the nozzle, after a semi auto cycle, the nozzle is pulled backward. The nozzle blocks the BB from feeding, he is 1 mm too much extended. I solve this problem but putting electrical tape between the hop up and the gearbox. But now I am back to 300 FPS because of this modification. It seems like, the more you get after market parts, the more you get problems due to incompatibilities.
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Last edited by Mobius; April 27th, 2015 at 14:25.. |
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