Colt AR-15 SP-1 Rifle Briefing
The Colt AR-15 has gone thru a number of design and marketing changes since
introduction in 1964. The following is a list of some of the highlights to help in
overcoming considerable confusion of this firearm for new or prospective AR-15 owners.
This discussion is for Colt manufactured AR-15's as opposed to the total history starting
from Armalite, and refers to civilian sales vs military.
Keep in mind that these rifles have been around long enough to have been modified by
owners to suit their personal tastes and according to their budgets. In other words, you
may find an AR-15 in any configuration, even with non-Colt parts substituted. This
makes identifying a genuine Colt AR-15 sometimes difficult as some replacement parts
are not easily identifiable as non-issued parts. To add to the confusion, in later
production, Colt mixed in A2 receivers amongst the A1 receivers to create some 2,000
AR-15's that are somewhat "odd-ball" models. It is hard to determine when Colt started
using only A2 receivers. And, as newer designed parts came along, they were introduced
when the old parts had been exhausted, such as the A1 buttstock being replaced by the
improved A1 buttstock with trapdoor and void for cleaning kit, and the fixed sling
It seems to be quite popular to create a "retro" SP-1 from available parts, not to
fraudulently resell, but to enjoy the clean lines of the early AR-15 rifle without paying
full price for a genuine model. While these are not out there in great numbers, be aware
that it is being done and ask the seller for all the information he has about the rifle to
determine as best you can its true origin. Many such rifles are built using a non-Colt
receiver which will be quite easy to spot.
Colt had two ID's for their rifles, a popular model identifier and an internal, more formal
identifier used to denote changes that the basic model number would not cover. An
example is the SP-1 which is more precisely known as the R6000. Another is the SP-1
carbine which is known as R6001.
In 1964, Colt introduced the AR-15 SP-1 which stands for Sporter One, the first
designation of the AR-15 for civilian use. "Sporter" was presumably used to appease the
1968 Gun Control Act which limits firearms in civilian hands to be essentially "for
sporting use only." Even though 1964 is obviously before 1968, this concept had been around since the Nazi Gun Control Act of 1938 and was being kicked around by Senator Thomas Dodd for several years prior to 1968 (read our article on the Gun Control Act of 1968 for a full history of Senator Dodd's involvement in Gun Control in America). This tactic would be even more apparent in later years when Colt
renamed the AR-15 to "Colt Sporter" and "Match Target" to bow to anti-gun political
pressure on the evil "black rifles" in the hands of American citizens. Colt even removed
the "dangerous" bayonet lug from later models, which they were not required to do by
law, to bow-down to political pressures. But, much to their credit, Colt has continued to
manufacture the AR-15 (a rose by any other name) for civilian ownership to this day.
SP-1 rifles were first shipped in plain brown boxes with no labeling other than hand
written R6000 model number and SPXXXXXX serial number through about 1966. Next
was a Tan label for model/serial number added to the box followed eventually by the
"green label" box in 1984. The SP-1 was sold from 1964 to 1985. Serial numbers start
with "SP." Early manufacture SP-1's are the most desirable and bring the highest dollar
value. It is not common to find an early SP-1 with box and all paperwork, thus, finding
one in this configuration commands a premium.
The SP-1's had the triangular handguards which were common to the Government Issue
models. They also had a "slab side" lower (A1 receiver) which means no guards or fences
around the magazine release pushbutton. Upper receivers did not have the forward assist
or protruding case deflector. The first style flash hider was the 3-prong model, later
changed to the birdcage model. All SP-1's had a bayonet lug on the bottom of the front
sight tower. Finish on early SP-1's was smooth compared to later models (say, 1971 and
on) where forging flashings were not thoroughly ground off the front sight tower and
carry handle as were early SP-1's. Some SP-1's may have the forward assist notches on
the bolt carrier even though they were devoid of the forward assist on the receiver. This is
not necessarily an indication of a parts change-out and is correct even for the fairly early
SP-1's. Very early SP-1's did not have the forward assist notches. SP-1's did not have the
auto-sear block in the lower receiver which Colt introduced later in the AR-15
manufacture. Earlier SP-1 (A1) buttstocks were without any provision for a cleaning kit
and had a rubber butt pad. Later issues had the improved buttstock with trapdoor for
cleaning kit and fixed rear sling swivel. Sights were basic (referred to as A1 sights), the
front sight being adjustable in elevation (for basic sighting-in) and the rear sight
adjustable in windage, with a dual aperture (large and small) flip sight for targets 0 to 200
yards and 200 yards and beyond.
There are many other subtleties to the SP-1 such as straight pistol grip, Edgewater buffer,
large hole upper, "straight" handguard slip-ring, miscellaneous stampings, casting marks,
chrome plated bolt, serial number range, "transition" parts, etc, that are important to the
story of the SP-1, but would take a vast write-up to cover.
To recap, the following points help to define the SP-1 rifle. Your SP-1 should conform
fairly close to these points. Variations could occur depending on the exact year it was
1. Produced 1964 - 1985.
2. A1 slab-side lower receiver
3. 3-prong flash hider (early), bird cage flash hider (later)
4. 1 in 12" twist
5. Serial number starting with "SP"
6. Bayonet lug
7. No forward assist
8. No spent case deflector
9. Without forward assist notches on the bolt carrier (very early), with notches on the
bolt carrier (early, and on)
10. Chrome plated bolt (very early), non-chrome plated bolt (early, and on)
11. A1 buttstock with rubber buttpad and moveable sling swivel (earlier), improved
buttstock with trapdoor and fixed rear sling swivel (later)
12. A1 sights
13. Triangular handguards (matte finish and semi-gloss variants exist)
14. Edgewater recoil buffer (earlier), solid recoil buffer with polymer aft end (later)
15. Straight handguard slip-ring
16. Straight pistol grip (without finger notch)
One popular urban legend laid to rest is that early AR-15's did NOT ship with M16 parts!
By the way, it is illegal to assemble an AR-15 with ANY part from an M16. This will get
you in big trouble, quickly! For this reason, use caution in buying AR-15's of questionable
origin or known "parts" guns unless sold by a reputable source.
SP-1 Carbine Briefing
The SP-1 Carbine (R6001) was introduced in 1977 and produced until 1985. This is
similar to the SP-1 Rifle but has a two-position collapsible buttstock, shorter, round
handguards, and a 16.1 inch barrel. Buttstocks are plastic-coated aluminum and remained
in that configuration till this model ceased production. The birdcage flash hider had long
been the standard model. Colt made a 9mm NATO variant of the carbine in the SP-1 era
but it has the serial number prefix of TA, and technically is not an SP-1. This is referred to
as an R6450 and is basically the same as the SP-1 .223 Rem - 5.56 NATO carbine but
with the attendant modifications for the different caliber and magazine.