Barrel length & fps

[Kev]

Hi.

Quick question and maybe very obvious so sorry in advance if this is a daft question.

If you change an inner barrel to a longer one with a tighter bore how much will this change the fps if any?

Cheers.  

[Hangtight]

The tighter bore might increase the fps by a little, and the longer barrel might decrease it if the cylinder doesn't have enough air volume.

[Sitting Duck]

The ratio between barrel & cylinder volume blah blah blah.....

Charts usually say of 1:1.5 to 1:2.5 blah blah blah.....

 

 

1:1.5 is too low imho - usually I'd say 1:1.75 to 1:2.00 for most guns there about

if using heavier bb's and DMR a ratio of 1:2.25 upwards blah blah blah....

 

Usually you need to try to match up the cylinder port to the barrel length to stay within the range

What actual volume ratio is perfect will vary but I'd say a 1.8 to 2 will do most

 

HOWEVER ensure when selecting the cylinder & port you do fit it the CORRECT way...

A daft noobie install guide from a gearbox repair kit shows how NOT to tech like a pro...

BELL-END TECH GUIDE - no wonder my first attempts at teching ended in disaster...

 

(actually I was/am still crap but use this as my first lot of excuses - an oldie but wtf still makes me chuckle)

 

blah x 3 is used coz it is a subject often debated and people's view/opinion/personal finding vary slightly

(blah blah blah....)

So I'm not going to go over this in detail blah blah blah where port volume blah & more blah's etc.....

 

If you have the tolerance in volume I have found fitting a longer barrel will increase fps by

100mm increase in barrel length = aprox 40fps increase

or ye olde = 1 inch = extra 10fps

 

NOTE - TBB will increase fps by about 15 to 20fps IF like for like

(swapping same barrel length for a TBB AND it functioning correctly)

(Wider barrels the fps drops)

BUT this is on the understanding that the barrel/bucking/hop is fitted correctly 101%

different hop units can work well/badly in some guns/setups eg: prowin feed issues in some M4's

or bad seals from poor fitting/assembly headaches - hence if all works like for like blah blah blah....

 

You will or should have a bit of leeway regarding volume and if you stay within the range blah blah blah....

You should see a fps increase or creep of about 40fps per 100mm or 10fps per inch blah blah blah

You can try it and see how it goes if not going too nutz

or make comparison what type of cylinder you have in there and see if you might have a bit of leeway

It is hard to quantify exactly as each gun/build is different but so far that is roughly what I have found

(Usual hope some of this helps & blah blah blah....)