I think there is a dramatic difference between a collection and an accumulation. Which are we talking about?
A collection is a group of anything..guns in this case which have a common thread to the collector. This thread does not have to be apparent to anyone but the collector. The beginning collector often shoots off in many directions, an important stage in collecting because the result is broad understanding of the subject resulting in pinpoint scope of interest as the collector advances. An advanced collector will attempt to keep his collection stealth and the corners round. An advanced collection is often as abstract as the last sentence. Some collectors maintain several different and distinct collections simultaneously, this is an eclectic collector.
An accumulation is a group, battery, arsenal, etc. A selection of something amassed to serve a purpose.
Does a mechanic have a collection of tools or an accumulation?
A farmer a collection of equipment or an accumulation?
A road construction company a collection of vehicles or an accumulation?
For collecting I like early hardware company branded shotguns.
A good accumulation IMO is something like this:
.
