Cutting down inner barrels

[Dynamo]

personally im more partial to using a lathe. it is really important the the end of the barrel be not only clean of any burrs, but also needs to be uniform.
i like to put a -5*< crown on my barrels. doesn't seems to affect the accuracy over the stock crown, but it does add a nice crisp pop when the BB leaves the barrel.

[KenTsui]

Damn, both methods look really clean!

[Rabbit]

Super clean!

I ended up using a dremel on it and plugging up the tube with some cloth.

Turned out extremely well - minor jagged bits, used a metal file, then some sand paper then finally a larger drill bit to get rid of the inside ones.

All in all it rests perfectly on a flat surface standing straight up so it doesn't look uneven, pushing it against my finger and spinning it I can feel nothing sharpe or damaging.

I did notice on the original end of the prometheus barrel it was quite concave - i dont know the reason for this but hopefully it doesn't affect anything.

BIG EDIT:
Wow..after the perfect trimming job, I attach the hopup - looks good - go to slip it down the upper receiver and the prometheus barrel is too thick for the jg outer barrel! FAIL.

[Dynamo]

Originally Posted by Remylebeau

BIG EDIT:
Wow..after the perfect trimming job, I attach the hopup - looks good - go to slip it down the upper receiver and the prometheus barrel is too thick for the jg outer barrel! FAIL.

lol yep, tight fit on some hopup units also, but they are awesome barrels.

[dice]

Originally Posted by Remylebeau

BIG EDIT:
Wow..after the perfect trimming job, I attach the hopup - looks good - go to slip it down the upper receiver and the prometheus barrel is too thick for the jg outer barrel! FAIL.

This happened with my VFC KAC PDW. put a longer tight bore to hide under the supressor and oops too big for the flash hider. The bonus was, I bored out the flash hider so the barrel has a nice tight fit. No barrel wobble at the flash hider.

Note: I used the Dremmel with cutoff wheel and the cone bit to finish. Didn't want to accidentally crush the barrel with a cutter. Worked great for me.

[one2three_us]

If you have a power drill, and Dremmel, you can first cut the barrel slightly longer than what you need, then put it on to the power drill, start filing with the power drill on. At last, use a fine file or cone sander to cone the barrel. I used this method to cut down a 7" 6.01mm barrel to 5.9"

[one2three_us]

here is the pic

[TANKMAN]

has anyone used a copper pipe cutter. its made not to warp or bend copper tubing

[one2three_us]

i thought the pipe cutter only work on softer material. If it works on still, just make sure u go slow and not putting too much pressure on the blade and barrel. Cone the tip afterward

[jordan7831]

Agreed. Pipe cutter CAN be used if you have no access to a lathe or anything like that. Just be sure to stuff a wad of tissue paper in the end near the cut to assist with easier cleanup. Also use something like the screw driver off a swiss army knife to clean up the burr that is left after cutting.

I like to also use digital calipers to measure the inner diameter of the inner barrel before cutting. Press the zero button and then measure the inner diameter after cutting. If the barrel was pinched even slightly it will show up on the caliper as a negative number since the barrel is now smaller than it was before.

[Deadpool]

Never use a pipe cutter, It'll crimp down the end and make it smaller then the rest of the barrel.

Use a metal saw and then debur the end to remove sharp edges.