Joining sleepers

[Diyisfun]

I have bought some 10mm x 200mm coach screws, with hex heads on.
I am joining some sleepers that are just edging to raised flower bed, so not structural. I cant make my mind up as to counter boring so has to hide the heads & give an extra bit of thread to join, or just have the raised head, what do others do?. (I cant fix on the inside as one layer of sleepers have been down for a while).

 

[captainpp]

I tend to countersink for the sake of tidyness. I also use washers to avoid the head itself sinking into the timber.

 

[Diyisfun]

Never thought about using washers, thanks for tip.