flat hopping bucking

[Jay91]

so im having my first attempt at flat hopping my bucking and was wondering how smooth do i need the old patch and groove to be? ive cut them down pretty close but wanted to double check before i try and sand it smooth if its neccesary seeing as i will be turning the bucking 90 degrees

thanks 

 

[Hangtight]

The flatter the better, otherwise you may run into problems getting the barrel and rubber into the hop up, and potentially air seal issues too.

 

[Jay91]

so i ended up getting my bucking pretty smooth and made my flat nub out of a rubber, it was chronoing fine at home then when i took it out today it started double feeding i had already ordered a few different buckings and nubs (including a modify flat hop and prommy blue flat nub) but they didnt arrive in time to bring with me 

but im curious what i did wrong that could have caused the double feed im thinking it could have been the nub wasnt deep enough but when i looked down the barrel i could see it protruding giving me the desired flat hop. any ideas? the bucking also felt a little soft and was well used but it seemingly worked fine prior to me modifying it

this is on a 450 fps dmr if that helps

 

[L3wisD]

i had already ordered a few different buckings and nubs (including a prommy blue flat nub)

Throw that straight in the bin.

I tried one and it was awful - I'd have been better using a condom!