Cutting an inner barrel - Best practice?
 

Rather than buying a whole new tightbore I figured id cut a longer one down to size with a dremel - of course taking care of jagged edges with some light sanding.

I'm kind of questioning wether or not this would affect bb trajectory - mainly because most inner barrels have a sort of concave tapering and I have no clue what effect this has already.

Thoughts?

I did it many times with great success, just make sure you chamfer the end of the barrel.

BrokenBird

A pipe cuttdr also works well just dont tighten it up much just a light grip cpl turns re tighten and so on.
I never had any issues by not tapering the inner end afterwards

+1 on the pipe cutters. I have done this before on lots of thin metal piping and it works great. Just take your time and don't apply too much pressure... then use than dremel to put a chamfer in the end.

Can anyone explain the reason the chamfer is there (the science behind it i guess) cause ive never put it on barrels ive cut i just run the deburer thing thats on the pipe cutter and havent noticed any ill effects from not havin it

As far as I know it is just to clear out any burrs and make sure the cut portion of the barrel is still round and has not oval-ed during cutting.

You're supposed to actually crown the barrel in such a way that it's an increasing diameter on the last 2-4mm of the barrel.

The "science" behind it is that with an increasing diameter the air pressure differential between the barrel and the outside air is less severe.

I see. I dont think it makes much of a difference in airsoft as far as i can research it doesnt even make much/any difference in real guns either as some have this and some dont alot of the reasons i read are to protect rifling and aid in pulling the cleaning brush back through.
As i said i havent had any ill effects from not doing it and ive cut down alot of barrels 8-10 at least.
Thanks for the explination!

You can do it with a hack saw and a clamp with a razor blade.
Be sure not to over tighten the clamp and use the hack saw to cut through once thats finished you can crown the inner part, be sure not to scratch the inner barrel, then proseed to clean it out after.

Okay whoa wait a minute.

What barrel are you cutting exactly? Because if you're cutting a Madbull or any kind of coated barrel you're going to crack the coating on it.
If it's a steel barrel, good luck using a hacksaw on that.
And if it's brass you're going to want to stabilize the barrel completely before cutting it to prevent warping as it's quite a bit softer than other barrels.

a pipe cutter a lathe or possibly a dremel tool are the "proper" ways to do it
lathe being the right way a dremel if you are handy with it will work but a pipe cutter is likely the next best way to a lathe so long as you dont crank it too tightly on soft barrels (read brass) a hack saw is a hack job and will do a poor job on most any barrel tho it can be done its not ideal

I've done all three. Hack saw works but you need to be more carful. Pipe cutter wins 7fold, and Dremel works too.

+1 on Stealth

To go into a bit more detail, The entire circumference of the muzzle needs to be perfectly proportional. If you have little nicks on the end of your barrel, or the bore diameter isn't "eased off" or crowned (expanding at the end, like you see on all new barrels), the gas pressure isn't evenly distributed around the bb when it leaves the barrel. In the case of burrs or shavings, they can either graze the bb on it's way out, or as I said before affect the gas pressure, both of which affect accuracy. In the case of sawing off your barrel without easing it off, even the most minute difference in barrel consistency at your muzzle will throw off the trajectory simply due to the rapid change in pressure. Even if the barrel was perfectly cut and cleaned up, the difference in accuracy between a crowned barrel and a "blunt" barrel if you will is quite dramatic.

Well at least theoretically. I doubt it will be noticable for airsoft at a hundred feet, but it sure makes a difference in a .308 at 100 yards.

Cheers

I'm running an AEG with a CQB outer barrel and a custom barrel extension (roughly 2 inches) bringing me to about a 340mm - 350mm inner barrel length (roughly give or take)

I was going to cut down a Madbull Python but after reading this post looks like im better off with something steel - but again after some of these posts, not to cut it at all! :) (dont have the crowning tools)

Doesn't look like anything 340mm - 350mm exists premade on the market today however this Prometheus looks to be as close as i can get - however its made specifically for the Masada..it doesn't look any different? Not sure if its compatible with fitment.

http://redwolfairsoft.com/redwolf/ai..._11_5_inch.htm