The Forage cap for officers was the same as that in the regulars with silver lace instead of gold.

from left to right 1 year, 6 years, 7 years, 8 years, 9 years and 10 years
Full Dress Uniforms
The Volunteer Artillery wore the same tunic as the regular artillery, but with scarlet collar, cuff knots and piping. The collar grenades were white metal. The permanent staff  (Such as Quartermaster etc) had silver round back cord knots and coller edging, while Sergeants had silver cord knots and collar piping. The gun was silver.  Volunteers did not have long service stripes and those distinctions were very different as described below. The Trusers wer the same as RA with wide scarlet stripe.
Full Dress Headdress
The 1878 Helmet (with ball after 1881) was similar to officers but with leather binding on the front and rear peaks. The helmet plate was white metal and stamped in one piece.

The Edinburgh and Glamorganshire Corps continued to wear the busby until 1902 or later. The 3rd Middlesex wore a special headdress (See below) 
Forage Caps (Pillboxes)
The Pillbox cap, worn from the 1860s, followed normal standards. Staff and Sergeants wore the officers caps
​with silver lace. Some examples show a cap with silver lace band with a silver netted buton only. Other ranks wore a cap with scarlet band and button. Like their regular counterparts, Corporals had a small double chevron above the band in front and Bombardiers had a single chevron. All Corps were able to wear a grenade on the front, but not all did. Some Corps had their own badges (See below)

The Volunteer Artillery did not wear good conduct badges. In their stead, a system of proficiency badges was authorized. For Sergents and above, a four pointed star was worn. (Fig. A). It was ordered to be worn above ALL badges on the right sleeve. (it was often worn below the crown, which was non-regulation).  The lozenge badge (Fig. B) was awarded to all Volunteers returned as efficient in rifle (or gunnery) drill during the last annual return of their corps. It was worn on the right lower sleeve. For volunteers returned "Efficient in gunnery drill" for five years in a row a five pointed star was awarded (Fig. C).    Additional stars were awarded for the 6th, 7th, 8th and 9th Years consecutively.  It was worn on the lower right sleeve, above the diamond.
See chart below for how it was arranged.
The Battery or Corps prizes from 1881 were as follows
1st Prize - Crossed cannons with studded shell in wreath above (Fig. D)
2nd Prize - Crossed Cannons (Fig. E)

From 1898 the cannons were changed to guns
​1st Prize - Crossed Guns with crown above (Fig. F)
2nd Prize - Crossed Guns (Fig. G)

Individual Prizes
1st Prize - G in Wreath with crown above (Fig. H)
2nd Prize - G in Wreath with Star above (Fig. I)
3rd Prize - G in Wreath (Fig. J)
Undress Frocks
The first frocks (in 1881) had five buttons and scarlet collar with scarlet trefoils on the cuffs. Sergeants and above had silver trefoils on the cuffs and some corps had silver piping on the lower collar (or even all round in some corps). A frock with patch pockets on the chest was worn by many corps from the mid-90s.  By 1900 the cuff trefoils had disappeared.
Field Service  Caps
Introduced in the mid 1890s, this cap was worn by all ranks. Sergeants and above had scarlet piping on the flaps and silver lace on the top folds. Other ranks had scarlet piping only on the flaps and top.  The grenade worn on the body was white metal.

Forage Cap Badges
These badges werre worn on the round forage cap from 1860. After 1881, the only official badge was the grenade in white metal. However, many corps continued to wear these badges until at least 1902. Some were worn on the Field Cap. There is not much information of which corps wore them and for how long.

Although the Government was eager for the Volunteer Artillery to stick to regulation dress, many corps felt their special uniforms should be allowed to be worn (Like the Rifle Volunteers). One Corps stood out. The 3rd Middlesex Artillery Volunteers. Their uniform was unique within the Artillery Volunteers. (See below). Most other corps continued to wear their own badges on caps, pouch belts and sabretaches. 
The 3rd Middlesex Artillery Volunteers
The Corps was raised by Lord Truro and over the years became somewhat of an Elite regiment and recruits were not difficult to find. In later years restrictions on height became the rule to maintain the xclusivity of the corps. In matters of uniform, the headdress was the most distinctive; The busby. Made from the fur of the Racoon, it was of a very light shade for other ranks and, as the tail was used for officers busbies, it had a darker and more mottled hue.
The 3rd Middlesex Artillery Volunteers
The uniform for other ranks was the same cut as for other volunteer corps. The piping on the tunic front and skirts were scarlet but the cuff knots were white. Officers' tunics conformed with the rest of the Artillery volunteers.

The forage cap had a scarlet band piped white above and below. (Silver for officers, staff and sergeants). The grenade on the front did not have any device on the ball, in fact it was the standard item.

The 2nd Northumberland Artillery Volunteers. Horse Artillery Detachment
The 2nd (Tynemouth) Artillery Volunteers formed a Horse Artillery detachment in 1864. This was worn until the mid 1890s. The uniform was the same as the Royal Horse Artillery except that officers had silver lace and other ranks had scarlet. The headdress worn is rather difficult to determine. In 1881 they were wearing the helmet, but beyond that it is not known if they ever adopted the RHA Headdress.

The uniforms worn by bands generally followed that of the Royal Artillery Band  except with silver lace. Since the cost of uniforms for bands came out of regimental funds, those of  many Corps had no special distinctions.

Band Headdress
Band members wore the same helmet had white metal metal plates and fittings. The 1st Cardigan Band had white plumes. Many bands whose Corps continued to wear the busbies, did so as well with red plumes.
Band Tunics
The 2nd Kent seem to have a uniform based on undress band tunics. The Lanarkshire modelled their uniforms on the RA Mounted band. The white collar was unique.
Trumpeters, Pipers & Drum-Majors

Trumpeters wore regimental uniform with the crossed trumpet badge on the upper right arm. Sergeant trumpeters (as shown above) wore the badge on the chevrons or above with aguillettes on the left shoulder.

Many Scottish Corps had pipes and drums. The piper of the 1st Banff above wears the Duff tartan.
Drum Majors
The majority of volunteer bands had bandmasters who wore more modest uniforms than the members of the band.  Some bands, including the East Yorks Corps pictured above, had drum majors. They often wore more flamboyant uniforms. The headdress was usually a bearskin with large red feathers.
The National Artillery Association was formed in 1863, three years after the National Rifle Association. Like the NRA, the NAA would foster interest in the Volunteer artillery both from a recruiting point of view and gunnery capability manner through competition. The Competitions took place at Shoeburyness by consent of the RA School of gunnery. The 1st competition was held in 1865. In 1885 the 3rd Middlesex corps won the coveted Queen's Prize and the so called Repositary Prize went to the 1st Essex. The badges, awarded to all gunners in the repective corps, were to be worn on the lower left sleeve above the cuff decoration. In addition to the badge the corps received a considerable monetary award.

There were also prizes awarded by the corps themselves. hiven to aindividual gunners or gun crews,they often were worn above any prize or qualification badges, which sometimes meant the upper sleeve.  
I am indebted to Ray Westlake for permission to use images from the book The Artillery Volunteers by him and
the late Norman Litchfield