Reducing FPS; building stubby upper for SR-16

Zack The Ripper · July 28th, 2014, 21:07

Question for the compression gurus out there, a hypothetical one.

I have a VFC SR-16 CQB with a m110 spring stock air nozzle, VFC precision hop unit, 300mm Prometheus 6.03 tight bore barrel, and a Prometheus purple rubber. All the O rings are well lubed and have great compression. It shoots 387-393fps using 0.20g BBs, with no hop on.

I am thinking about doing a stubby upper for some CQB use. I'm trying to determine how short I should go exactly as I don't want to compromise too much on performance, but I want something short enough to have me as close to 350 as possible. Anyone hazard a guess as too what length barrel that might be? 150mm? 170mm?

Thanks.

ThunderCactus · July 28th, 2014, 22:02

If you ran the same length of barrel and used an orga 6.13, you'd probably get REALLY close to that 350fps range
a 9" 6.13 barrel should drop it low enough

pestobanana · July 28th, 2014, 22:24

New Deep Fire M4s with the power up suppressor add about 250mm to gain 50 FPS. Maybe try a 200mm barrel, slightly wider bore and a PDI W-Hold to drop the FPS.

Spike · July 28th, 2014, 22:30

Quote:

Originally Posted by ThunderCactus

If you ran the same length of barrel and used an orga 6.13, you'd probably get REALLY close to that 350fps range
a 9" 6.13 barrel should drop it low enough

This. Or go full retard and get a 6.23.

lurkingknight · July 28th, 2014, 22:36

300 mm is already pretty short I Think there's only 2 more steps down in terms of length that are commonly available unless you go with something like an mp5k barrel.

Definitely have to go with wide bore to drop FPS as well, there's not much length to lose. You'll be overvoluming so you'll probably see some joule creep when using heavier rounds.

ThunderCactus · July 29th, 2014, 00:47

joule creep isn't quite so prevalent with widebores, it allows enough air to escape around the BB, so the pressure behind it really drops.
And at 6.23 I really doubt you'd ever get enough pressure OR volume to get it to work properly on an AEG lol

lurkingknight · July 29th, 2014, 00:55

you're probably right, but I get about .3J on my g36 going from .2s to .32s... more if I turn up the hop up.

Zack The Ripper · July 29th, 2014, 11:02

Thanks for the tips guys. I'll do some experimenting.

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July 28th, 2014, 21:07	#1
Zack The Ripper Trader rating Join Date: Jul 2012 Location: CFB Shilo, MB	Reducing FPS; building stubby upper for SR-16 Question for the compression gurus out there, a hypothetical one. I have a VFC SR-16 CQB with a m110 spring stock air nozzle, VFC precision hop unit, 300mm Prometheus 6.03 tight bore barrel, and a Prometheus purple rubber. All the O rings are well lubed and have great compression. It shoots 387-393fps using 0.20g BBs, with no hop on. I am thinking about doing a stubby upper for some CQB use. I'm trying to determine how short I should go exactly as I don't want to compromise too much on performance, but I want something short enough to have me as close to 350 as possible. Anyone hazard a guess as too what length barrel that might be? 150mm? 170mm? Thanks. __________________ Guardians of Asgaard

July 28th, 2014, 22:36	#5
lurkingknight "bb bukakke" KING! Trader rating Join Date: Jul 2011 Location: Ottawa	300 mm is already pretty short I Think there's only 2 more steps down in terms of length that are commonly available unless you go with something like an mp5k barrel. Definitely have to go with wide bore to drop FPS as well, there's not much length to lose. You'll be overvoluming so you'll probably see some joule creep when using heavier rounds. __________________ I futz with V2s, V3s and V6s. I could be wrong... but probably, most likely not, as far as I know.

July 29th, 2014, 00:55	#7
lurkingknight "bb bukakke" KING! Trader rating Join Date: Jul 2011 Location: Ottawa	you're probably right, but I get about .3J on my g36 going from .2s to .32s... more if I turn up the hop up. __________________ I futz with V2s, V3s and V6s. I could be wrong... but probably, most likely not, as far as I know.

July 28th, 2014, 22:02	#2
ThunderCactus Not Eye Safe, Pretty Boy Maximus on the field take his picture! Trader rating Join Date: Feb 2007	If you ran the same length of barrel and used an orga 6.13, you'd probably get REALLY close to that 350fps range a 9" 6.13 barrel should drop it low enough

July 28th, 2014, 22:24	#3
pestobanana Squid Porn Superstar, I love the tentacles! Trader rating Join Date: Nov 2008 Location: Richmond Hill and Waterloo, Ontario	New Deep Fire M4s with the power up suppressor add about 250mm to gain 50 FPS. Maybe try a 200mm barrel, slightly wider bore and a PDI W-Hold to drop the FPS.

July 29th, 2014, 00:47	#6
ThunderCactus Not Eye Safe, Pretty Boy Maximus on the field take his picture! Trader rating Join Date: Feb 2007	joule creep isn't quite so prevalent with widebores, it allows enough air to escape around the BB, so the pressure behind it really drops. And at 6.23 I really doubt you'd ever get enough pressure OR volume to get it to work properly on an AEG lol

July 29th, 2014, 11:02	#8
Zack The Ripper Trader rating Join Date: Jul 2012 Location: CFB Shilo, MB	Thanks for the tips guys. I'll do some experimenting. __________________ Guardians of Asgaard

Reducing FPS; building stubby upper for SR-16

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