When bottling off a keg why are my bottles having very little carbonation?

[galacticbrewing12]

I keg all my beer and have been doing so for the past 2 years. Most recently I have started bottling my beer off of the keg in order to submit bottles for homebrew competitions. Unfortunately, in both the competitions I have entered my beer in the carbonation has been almost non-existent.

I have tried a few different techniques. One, I have bottled the beer using a growler filler and the CO2 set at about 5 psi letting the beer fill with about 2-3 inches of headspace which is generally filled with some foam. The other technique I have used is bottling using a 6 foot party tap and pushing out the beer at about 5 psi with about the same amount of head space. I clean all my bottles with Star San and then have even tried leaving the bottles in the fridge for a bit to keep them cool.

Any idea why this is not working and what alternative techniques I could try?

 

[Tombstone0]

When I bottle from the keg I use a picnic tap with about 6 inches of tubing attached to it. I over carb my keg a little bit and fill my bottles to the brim. I figure less headspace means less chance for oxidation.

 

[MrFoodScientist]

Here are a couple of causes for carbonation loss:

1) CO2 comes out of solution to fill the headspace.
2) Carbonation is lost in turbulent pouring.

-Use a larger bottle so the headspace to total beer volume is minimal. I suppose competitions may not allow this, but generally it does help.

-Use a stopper with your tubing to maintain pressure and reduce pouring turbulence. The low psi helps, but you will be amazed at what a stopper will do. You have to burp it frequently, but it keeps carbonation quite well.

-Slightly overcarbonating in the keg may help, but it could also cause additional foaming which could exacerbate the problem. Use that method with caution. Plus, now you've got a mostly full keg that is overcarbonated, so you have to weigh that against competition bragging rights.