Extending barrel

Corbin · November 17th, 2007, 23:42

If I put a longer barrel on my AK (RPK Conversion) Will I need to modify anything so it doesn't negatively effect my fps? or will it give me more fps because of it?

ILLusion · November 18th, 2007, 00:53

How long is the RPK inner barrel?

Goodl2ussian · November 18th, 2007, 00:57

definately wont give you more FPS

mateba · November 19th, 2007, 13:25

Depending on how tight it is you should be ok with a type 0 cylinder or a bore-up kit especially if you use a tighter barrel. If its a stock barrel, 6.08+, than you should be able use 590mm without drastic negative affects. I do believe you need a 590mm barrel for the RPK. I would not use a 6.01mm due to barrel suck, stock might the best way to go on this one. If you need to bump your FPS a little add a spacer on your spring guide, tweak your compression or use a stronger spring.

ILLusion · November 19th, 2007, 13:34

mateba, you have that reversed.

A tightbore inner barrel has less internal volume than a larger bore inner barrel would, and as a result, you're more likely to require a bore-up kit on a STOCK inner barrel, and less likely to require a bore-up kit if you use a tightbore.

Of note: I've used a Systema M120S and PGC M130 spring on a 590mm 6.03mm inner barrel before and tested performance with both a Systema Type-0 inner barrel as well as a Systema Bore-Up kit and noticed zero difference in performance.

mateba · November 19th, 2007, 14:08

ok

Corbin · December 29th, 2007, 18:58

So if i get a 6.04 PSG-1 barrel my Fps shouldn't go down by more than like 20 Fps?

CDN_Stalker · December 29th, 2007, 20:21

Tightbore should add about 10fps to your velocity. Is just a general rule of thumb though.

Incidentally, I cut a stock barrel to 330mm and installed it in my MP5-SD (stock had a 229mm) and saw my velocity go from 365fps to 387fps simply because of that extra 100mm of inner barrel.

Corbin · December 29th, 2007, 20:35

Hmmm, a 590mm barrel is only a 140mm upgrade, so i guess ill get the PSG-1 and hope there is little or no negative effects.

ILLusion · December 29th, 2007, 20:45

Be aware that there are two PSG-1 inner barrel lengths: 590mm and 650mm.

Corbin · December 29th, 2007, 20:48

Ya, Im trying to figure out what i could fit with the extension im getting (http://airsoftglobal.com/product_inf...oducts_id=4595)
so ill decide once I know that.

ILLusion · December 29th, 2007, 20:54

If you get the 650mm, you will HAVE to get a bore-up kit and an M120 or stronger spring to power it.

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November 18th, 2007, 00:53	#2
ILLusion GBB Whisperer Trader rating Join Date: Jun 2002 Location: Toronto	How long is the RPK inner barrel? __________________ *Advanced Airsoft Armaments and Enhancements* Quick to the gun, sure of your grip. Quick to the threat, sure of your shot. Diligentia, Vis, Celeritas Accuracy, Power, Speed

November 19th, 2007, 13:25	#4
mateba Trader rating Join Date: Feb 2007 Location: Alabama, USA	Depending on how tight it is you should be ok with a type 0 cylinder or a bore-up kit especially if you use a tighter barrel. If its a stock barrel, 6.08+, than you should be able use 590mm without drastic negative affects. I do believe you need a 590mm barrel for the RPK. I would not use a 6.01mm due to barrel suck, stock might the best way to go on this one. If you need to bump your FPS a little add a spacer on your spring guide, tweak your compression or use a stronger spring. Last edited by mateba; November 19th, 2007 at 13:29..

November 19th, 2007, 13:34	#5
ILLusion GBB Whisperer Trader rating Join Date: Jun 2002 Location: Toronto	mateba, you have that reversed. A tightbore inner barrel has less internal volume than a larger bore inner barrel would, and as a result, you're more likely to require a bore-up kit on a STOCK inner barrel, and less likely to require a bore-up kit if you use a tightbore. Of note: I've used a Systema M120S and PGC M130 spring on a 590mm 6.03mm inner barrel before and tested performance with both a Systema Type-0 inner barrel as well as a Systema Bore-Up kit and noticed zero difference in performance. __________________ *Advanced Airsoft Armaments and Enhancements* Quick to the gun, sure of your grip. Quick to the threat, sure of your shot. Diligentia, Vis, Celeritas Accuracy, Power, Speed

November 18th, 2007, 00:57	#3
Goodl2ussian Trader rating Join Date: Oct 2007 Location: Calgary, AB	definately wont give you more FPS

November 19th, 2007, 14:08	#6
mateba Trader rating Join Date: Feb 2007 Location: Alabama, USA	ok

December 29th, 2007, 20:21	#8
CDN_Stalker Official ASC Bladesmith Trader rating Join Date: Jul 2003 Location: Ottawa, Ont.	Tightbore should add about 10fps to your velocity. Is just a general rule of thumb though. Incidentally, I cut a stock barrel to 330mm and installed it in my MP5-SD (stock had a 229mm) and saw my velocity go from 365fps to 387fps simply because of that extra 100mm of inner barrel. __________________ STKR Knives http://www.facebook.com/#!/pages/STK...17036668380871

December 29th, 2007, 20:45	#10
ILLusion GBB Whisperer Trader rating Join Date: Jun 2002 Location: Toronto	Be aware that there are two PSG-1 inner barrel lengths: 590mm and 650mm. __________________ *Advanced Airsoft Armaments and Enhancements* Quick to the gun, sure of your grip. Quick to the threat, sure of your shot. Diligentia, Vis, Celeritas Accuracy, Power, Speed

December 29th, 2007, 20:54	#12
ILLusion GBB Whisperer Trader rating Join Date: Jun 2002 Location: Toronto	If you get the 650mm, you will HAVE to get a bore-up kit and an M120 or stronger spring to power it. __________________ *Advanced Airsoft Armaments and Enhancements* Quick to the gun, sure of your grip. Quick to the threat, sure of your shot. Diligentia, Vis, Celeritas Accuracy, Power, Speed

Extending barrel

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