Curious as to what you define a "Volunteer" Rifle Musket.
The Volunteer movement in Great Britain was akin to the US National Guard. It was founded in 1859 and later that year the NRA(GB) was formed. The creation of the Volunteers and NRA with its annual rifle meeting (first held in 1860) generated a demand for rifles.
The Pattern 1853 Rifle Musket became the arm of issue of the Volunteers and many were made privately. See "Enfield" Volunteer Rifle - De Witt Bailey II.
Guns Review, UK. Part One, May 1970. Part Two, June 1970.
If, however, you refer to the generic type of military match rifle as typified by the modern reproduction "Volunteer" by Parker-Hale, they were not "English Gentleman's Guns." Many gunmakers, including Kerr, Turner and Whitworth made military match style rifles for use in 'any rifle' NRA competitions by the Volunteers. These rifles were typically of .451 bore and known as small-bore rifles as opposed to the large bore (.577) service rifle.
They did evolve into highly specialised long range target rifles which would have been out of the range of many to purchase.
As to the ACW, I believe there is some documentation as to the importation of some Kerr rifles but this may have been extremely limited.
See my Resource List at
http://www.lrml.org/resources/index.htm for more information on these rifles.
David
