question

[watto]

Hi
Should the part of the barrel that contacts the piston be sharp or completely flat.
thanks

[jackssmirkingrevenge]

Sharp will dig into your seal like a cookie cutter. Completely flat will do the same. What you want is to cut it at an exact right angle then bevel the edges slightly with light sandpaper.

In short:

> - bad

] - bad

) - good

[Novacastrian]

Just how my barrel is for my incomplete pneumatic

[jackssmirkingrevenge]

Just how my barrel is for my incomplete pneumatic

...which we would really like to see finished *hint hint nudge nudge*

[psycix]

Sharp will dig into your seal like a cookie cutter. Completely flat will do the same. What you want is to cut it at an exact right angle then bevel the edges slightly with light sandpaper.

In short:

> - bad

] - bad

) - good

thanks for this information
I was always wondering it but not asking since I am not building a pneumatic yet.

[meatballs]

you want it to make good sealing contact so it dosn't leak, which is easier with a more pointed edge, but you want to avoid cutting through the sealing face. so i would change that analysis slightly:

> - bad

] - fine, but not the best. can work fine.

) - ideal