I always thought it a good idea to have a closed end when working to avoid anything getting in the barrel and to protect the crown in care I take a spill. It's easy enough to tap out the holster every few days or weeks, if necessary.
EP Saddlery is just down the road from me and I went in a few weeks ago and they told me they could modify any of their rigs to have a closed end - no extra charge. My current holsters are all closed end and I've never had a problem with debris.
Sounds good.
