M4 Inner barrel upgrade/measurement

MultipleParadox · May 16th, 2011, 23:40

Hi guys, I've been looking around almost all day for this but still have some unanswered questions.

I have a King Arms M4 Larue 7 inch (basically CQB length)
I wasn't sure about how the inner barrel is actually measured so I figured it was end to end once removed, and mine is 315mm.

I'm trying to find some good quality (prometheus/laylax, or if you know other brands with a great quality price ratio) tightbore in that length, but the closest I could find is like 300mm or 365mm... Could anyone help me on this? or is it that my barrel is actually a 300mm and I measured it incorrectly?

Also, I was wondering if I should consider changing/upgrading my cylinder/piston set if I go tightbore? everything in the rifle is stock currently except for a small upgrade of the spring (PDI 140%, and currently chrono'd at 340-360fps).

I've been reading about boreup kit, silents pistons (which I find interesting), ported or not, and such, and am a bit confused. I do understand most of what's what and all, but am still confused about which way should I go and if I do need to upgrade actually.

Any advices are welcome, thank you very much!

MP

MultipleParadox · May 17th, 2011, 10:20

Anyone?
Must not be that complicated is it?

venture · May 17th, 2011, 10:43

the 300mm barrel is fine. it is only a half inch shorter than your stock barrel. it will work perfectly.

Specs · May 17th, 2011, 10:55

get a 300 mm

MultipleParadox · May 17th, 2011, 11:11

Alright, I was kind of hesitating because I did't really want to get a shorter one. From your comments and thinking about it, I guess it won't make a difference that great.

What about cylinder and piston? Should I run stock until something fails? My initial reasoning was driven by the fact that if I reduce the inner barrel volume, maybe I should change the cylinder and what not?

edit: Man, even 300mm are hard to find... Sent a few emails here and there, we'll see what comes up.

To increase my chances, anyone has good brand to recommend beside prometheus?

Thanks

m102404 · May 17th, 2011, 12:24

5-15mm either way (especially shorter) is unlikely to cause any problems with mis-matching with your cylinder.

If you're dead set on a certain length...then an option is to custom cut one. Doing it on a lathe is the best way to do that. It's also best if the material is brass (cuts really easily and cleanly) or stainless steel (harder, but can be cut and finished nicely).

Bore up parts are not needed unless your inner barrel is very long.

Silent head systems, sorbo setups, etc....are up to you. I like the Silent setups....many prefer the Sorbo setups. Regardless...buy main line brands....element/clone parts suck ass.

MultipleParadox · May 17th, 2011, 13:17

Great answer m10, thanks for that, will continue my hunt for a few

Thanks

MP

coach · May 17th, 2011, 13:19

Can you see your inner barrel looking at the flash hider?

with the inner barrel installed, how much length is there from the end of the inner barrel to the end of the flash hider? take your unjamming rod and insert it until it touches the IB. add the extra length to your IB's 315mm's and that will give you the maximum IB length. This will open up some options for you when shopping for a new one.

It's not terrible to have the IB exposed as long as it doesn't extend beyond the flash hider.

MultipleParadox · May 17th, 2011, 14:30

Yes I guess I should consider that option
Haven't measured it that way yet, but I know my IB ends right before the flash hider starts, so it's probably not really long probably 4-5 cm. Will see tonight. Other option would be to get a slightly longer flash hider too, but I'm not too sure of going the suppressor way though.

Also I have to figure out how to remove the actual flash hider eventually, it seems stuck in there, probably lock-tite'd. I think hot water should work?

Newb Question: When unscrewing on anti-clockwise threads, does that means I have to "screws" to "unscrews"? :P

Sandrock · May 17th, 2011, 15:26

there might be a grub screw on the flashhider that is also holding it in place.

coach · May 17th, 2011, 16:24

Quote:

Originally Posted by MultipleParadox

Yes I guess I should consider that option
Haven't measured it that way yet, but I know my IB ends right before the flash hider starts, so it's probably not really long probably 4-5 cm. Will see tonight. Other option would be to get a slightly longer flash hider too, but I'm not too sure of going the suppressor way though.

Also I have to figure out how to remove the actual flash hider eventually, it seems stuck in there, probably lock-tite'd. I think hot water should work?

Newb Question: When unscrewing on anti-clockwise threads, does that means I have to "screws" to "unscrews"? :P

well if you have 4-5cm adding that to your 315mm gets you 355-365mm. so right there it gives you options for in stock availability at airsoft parts. you don't have to stick with exactly what your gun comes with.

MA TBB: http://www.airsoftparts.ca/store2/in...oducts_id=1356

Madbull TBB: http://www.airsoftparts.ca/store2/in...roducts_id=301

both are 363mm and should come just inside the edge of your flash hider.

depending on what your current setup is, you *might* need to change your cylinder.

venture · May 17th, 2011, 18:29

i have a 300mm guarder tb barrel. pm me if interested.

MultipleParadox · May 17th, 2011, 19:32

I measured my the flash hider: 45mm, just small enough to have a 365mm stick out the front... doh!

So I'm thinking about getting a longer flash hider. I was thinking about this one, what do you guys think? I fear it'd appear awkward due to its length (about 100mm) :/

coach · May 17th, 2011, 19:56

Lol. Just wait for Jugglez to get the 300mm tbb's instock or buy the one above

You're not loosing much if anything with it 15 mm shorter. You're already gaining some with it being a TBB.

Btw, when you measured, did you remove the barrel from the hopup?

MultipleParadox · May 17th, 2011, 21:20

Hehe ok, I think I'm overcomplicating all this a bit :P
I'll just wait for the Madbull one to come back in stock then

And yes I did remove the barrel before measuring it

Also, I tried to remove my flash hider, without success

No grub screws to be found anywhere, I let it rest a bit in hot water in case it was lock-tite'd, and even used vise-grips (with cloth around the flash hider), and all I managed to do is to damage the hider a bit despite of the cloth

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May 17th, 2011, 10:43	#3
venture Trader rating Join Date: Jun 2005 Location: Halifax	the 300mm barrel is fine. it is only a half inch shorter than your stock barrel. it will work perfectly. __________________ Visit us at :www.ventureairsoft.ca

May 17th, 2011, 10:55	#4
Specs Trader rating Join Date: Dec 2007 Location: Victoria City	get a 300 mm __________________ Kingston airsoft, we do it better.

May 17th, 2011, 15:26	#10
Sandrock Trader rating Join Date: Dec 2003 Location: Kitchener	there might be a grub screw on the flashhider that is also holding it in place. __________________

May 17th, 2011, 12:24	#6
m102404 Tys Trader rating Join Date: Apr 2006 Location: Toronto	5-15mm either way (especially shorter) is unlikely to cause any problems with mis-matching with your cylinder. If you're dead set on a certain length...then an option is to custom cut one. Doing it on a lathe is the best way to do that. It's also best if the material is brass (cuts really easily and cleanly) or stainless steel (harder, but can be cut and finished nicely). Bore up parts are not needed unless your inner barrel is very long. Silent head systems, sorbo setups, etc....are up to you. I like the Silent setups....many prefer the Sorbo setups. Regardless...buy main line brands....element/clone parts suck ass.

May 17th, 2011, 13:19	#8
coach aka coachster Trader rating Join Date: Mar 2008 Location: T dot	Can you see your inner barrel looking at the flash hider? with the inner barrel installed, how much length is there from the end of the inner barrel to the end of the flash hider? take your unjamming rod and insert it until it touches the IB. add the extra length to your IB's 315mm's and that will give you the maximum IB length. This will open up some options for you when shopping for a new one. It's not terrible to have the IB exposed as long as it doesn't extend beyond the flash hider.

May 17th, 2011, 18:29	#12
venture Trader rating Join Date: Jun 2005 Location: Halifax	i have a 300mm guarder tb barrel. pm me if interested. __________________ Visit us at :www.ventureairsoft.ca

May 17th, 2011, 19:56	#14
coach aka coachster Trader rating Join Date: Mar 2008 Location: T dot	Lol. Just wait for Jugglez to get the 300mm tbb's instock or buy the one above You're not loosing much if anything with it 15 mm shorter. You're already gaining some with it being a TBB. Btw, when you measured, did you remove the barrel from the hopup?

M4 Inner barrel upgrade/measurement

Upgrades & Modifications