Competing With the Past


More than thirty years ago, the article “AR-15 Match Loads” by Al Miller was published in Handloader magazine. As you would expect, the article chronicles Al Miller’s endeavors in developing accurate loads for the AR-15. The AR-15 he used in developing his match loads was an A1 version. (Did I mention this was done 30 years ago?)




Even though the M16A2 replaced the M16A1 as “Standard A” for the U.S. Military in November of 1983, the A1 has several characteristics that many people still find desirable today. Foremost would probably be the light weight of the rifle, which is due in no small part to the A1 barrel. The A1 barrel weighs several ounces less than an A2 government profile barrel (and one pound, 4 ounces less than an HBAR). Comparing the profile of an A1 barrel to an A2 barrel, we see that the weight reduction occurs in the area from the gas block to the muzzle.






Another feature of the A1 model that many people like is the simplicity of the rear sight. It is a “set it and forget it” affair with adjustment for windage only.





A third feature of the A1 model often mentioned is the shorter length of pull when compared to the A2 model. The A1 stock is 5/8” shorter than the A2 stock. [While the A2 stock is longer than the A1 stock, it is made of improved materials making it 10 to 12 times stronger than the A1 stock. (All the better to butt-stroke you with, my dear!)]


I have an unfired, 20” Colt A1 barrel assembly in excellent condition that I’ve been saving to use for a 20” KISS type build. As Colt introduced the first AR-15 A2 model to the civilian market around 1984 and stopped producing the A1 Sporter model around 1985, I’m going to take a S.W.A.G. and say that the A1 barrel that I have is over 20 years old! The barrel is stamped “C MP CHROME BORE” and has a 1:12” twist.






While I wanted to keep this KISS build as reasonably light as possible, I did want to make a few changes from the standard A1 configuration. One complaint generally heard against the A1 barrel is that it is “not very accurate,” though most often the complaint is made without any quantifying data being presented. Also, the A1 model uses the triangle handguards that are known for having poor heat dissipation and easy breakage. I decided to replace the triangle handguards with a 1st generation JP Enterprises free float tube to aide in heat dissipation and in ringing out all the available accuracy of the A1 barrel. The JP tube and barrel nut replace the triangle handgurads, handguard endcap, barrel nut and delta ring assembly. The JP free float tube and barrel nut actually weigh 1 ounce less than the original parts that they replace.





While I like the simplicity of the windage-only feature of the A1 sight, I prefer the sight aperture of the A2 sight. The “long distance” aperture of the A2 sight is about 0.010” smaller than the A1 aperture and the A2 aperture also has the “ghost ring” aperture for up close/low light shooting that is lacking on the A1 sight. Enter, the LaRue Tactical Back Up Iron Sight. This sight uses an A2 aperture but has adjustments for windage only; exactly what I was looking for. The sight attaches to the Picatinny rail of a flat-top upper receiver using LaRue’s throw lever mount.






You’ll notice in the last sentence that I said flat-top upper receiver. An A1 upper receiver weighs 9.9 ounces. An A4 flat-top upper receiver with the LaRue BUIS attached weighs 11.5 ounces for a difference of 1.6 ounces. Using the JP free-float tube along with the flat-top upper receiver and LaRue BUIS for this build gives me a net weight gain of only 0.6 ounces more than a standard A1 upper group. It also gives me the option of adding optics to the flat-top upper receiver and rails in just about any position I might need them on the JP free-float tube. Even though the LaRue sight is referred to as a back-up sight, I’ll be using it as the main sight on this KISS build.


The completed 20” KISS build weighs in at 6 lbs 15 oz. Here are a few pics of the the build.
















For his article “AR-15 Match Loads”, Al Miller used six different powders and five different bullets in testing, including Sierra’s 52 grain boat-tail hollow point bullet. He tested his loads off a bench at 100 yards using front and rear bags and a scope. His groups ranged from 0.75” to 2.75”. Unfortunately, he did not fire any 10-shot groups (I guess he didn’t get the memo. ) All of his groups consisted of 5 shots each.

Using his best tuned load, Al Miller turned in ten, 5-shot groups that had an average extreme spread of 1.075”. While these were only 5-shot groups, I was extremely impressed that he was able to obtain that level of accuracy using an A1 barrel. I was curious to see how my twenty year old A1 barrel would stack-up against his. (Obiously, I had an advantage with the free-float tube.)

Using one of my standard handloads for Sierra’s 52 grain MatchKing, I fired ten, 5-shot groups in a row from the bench at 100 yards (using front and rear bags and a scope) with the following results:

0.81”
1.10”
1.04”
1.34”
0.66”
0.73”
1.01”
0.98”
0.93”
1.08”

The average extreme spread for my ten groups was 0.968”. Following my standard protocol for accuracy testing, I also obtained three 10-shot groups from 100 yards that measured:

1.39”
1.26”
1.40”

Those three, 10-shot groups had an average extreme spread of 1.35” and more importantly the three groups overlayed on each other using RSI Shooting Lab had a mean radius of 0.45”. Here are some pics of the best groups.














In 1964, during testing for report number DPS-1471, the US Military conducted accuracy testing of production M16 rifles (which had the same barrel as the M16A1.) With the rifles secured in a machine rest, three 10-shot groups were fired (hmm . . . where have I heard that before) from 100 yards using M193 ammunition. “The average extreme spread of the groups ranged from 2.6 to 3.6 inches.”

For nostalgia sake, I fired three, 10-shot groups of IMI M193 off the bench at 100 yards from my A1 barreled upper. The average extreme spread of the three groups was 3.00”.

cool write up!  thanks for taking the time and posting.  

Nice write-up, and excellent accuracy from a 1:12 twist barrel!

Thanks.

.
.

The excellent accuracy was made possible by using Sierra's 52/53 grain match bullets. I have a nearly identical build. After letting an old A1 barrel sit in the basement corner for over a decade somehow I discovered I had enough extra parts laying around to put it back in to action.

The trhoat was rough so I fired a kit of Tubb's Final Finish through the barrel and it smoothed right out.

I used the cheapest, lightest free float tube I could find (on sale) which was DPMS's lightweight (carbon?) fiber 2" tube. After installing the barrel I epoxied it in place. Using my calibrated eye I drilled two holes at BDC and installed a short piccatinny rail designed for 2" tubes to attach a sling swivel and/or bipod when needed. The rail came with a backing threaded plate which sits inside the tube.

The total weight is less than the original. I'm using LMT's BUIS, the original front sight base and a Burris Fast Fire shimmed to co-witness with the irons.

This is a great blaster rifle which continues to give 100% reliability and zero concerns regarding "shooting out the barrel". Combat rifle matches are fun to run, but I'm considering a muzzle brake because of the light weight. Any M193 ammo feeds and functions flawlessly.

Loads that hammer are 20.6 grains of H-4198 with 52/52 grain SMK's.

                                     26.0 grains of WW-748

                                     22.5 to 23.0 grain H-322

I also run Cavalry Arms A1 length stock and actually prefer it to the A2. I'm using the A2 butt plate because it has more grip. A collapseable may be tried in the furture.                                        

A few thoughts:

1. Early A1's had a small aperture on the short and long range sights while the later ones had a ghost ring aperture on the short range sight leaf.  So in effect, you don't have to deviate from the A1 upper and sight to get it either way.

2. The 1-12 twist barrel delivers excellent accuracy with bullets up to 55 grains.  1-14 was standard for .223 in longer barrells with slightly more velocity.  In really cold weater (ie. really dense air) the 1-14 twist gives only marginal stability to a 5 grain FMJ at M193 velocities, so the 1-12 twist was adopted.  In short, excellent accuracy from a 1-12 twist barrel with bullets weighing 55 gr or less is not surprising, it is just the norm.  faster twist barrels did not come along until bullets larger than 55 grs made an appearance as it simply was not needed.  

3. On both my A1 uppers (one with a Colt barrell and the other with a  Sako defense barrel) with a 4x Colt scope I have been able to get 1.5 MOA accuracy with 55 grain FMJ handloads  and 1.0 MOA with 52 grain Sierras. In short, the A1 does not get the credit it deserves for accuracy.

4. The major accuracy issues with the A1 are: a) the need to have very consistent pressure on the fore end when shooting, especially as the barrel heats up (it will not tolerate much sling pressure before groups start getting wide) and 2) the limitaitons of the sights.  Shooting 1 MOA groups with a smaller aperture and finer front post is not a problem.  Back in the day when I first started shooting an AR in national matches, I soldered a plate on the rear sight leaf over the existing hole to allow me to drill a smaller aperture and I turned down the front sight pin to produce what amounted to the same sight picture I got with a match grade M14.  

5. For general purpoise shooting, I still prefer the A1, it is light, simple, has excellent balance and ergonomics and shoots very well if the shooter does his part.

I have a 1973 SP1 with a colt 4x scope and it shoots 1.5 moa 10 shot groups with LC 1984 M193 loads (I have a ton of this ammo that I only saved for this rifle)and is one of my favorite plinkers that I shoot.I remember me and my brother years ago shooting that sucker with open sights and people could not believe the way we could hit beer cans as long as we could see them through the sight and get the post on them we could pop them.All our friends when we were kids used to think that gun was fake and a toy cause it was so light and all the plastic parts on it; till they saw it shoot.

Molon again another nice, very interesting piece. I keep my older SP-1 Carbine plain jane for the fact that with 55gr BT in my handloads it is old but accurate and super reliable.

some of us were blessed to obtain BRAND NEW colt A1 barrels awhile back, from bubba guns.

I was amazed at the quality. I mean perfect.


T marked flat top-key hole upper, RRA bcg, colt sporter stock, EA lower. all new parts head to toe.

everything fit perfect,zero wobble between upper and lower.  I never bench rested it, but was shooting amazing groups at 80 or so yards,just resting the rifle


thanks a bunch for this write up.

In 1964, during testing for report number DPS-1471, the US Military conducted accuracy testing of production M16 rifles (which had the same barrel as the M16A1.) With the rifles secured in a machine rest, three 10-shot groups were fired (hmm . . . where have I heard that before) from 100 yards using M193 ammunition. “The average extreme spread of the groups ranged from 2.6 to 3.6 inches.”

I happen to have the orginal Weatherford Colt owners manual for my rifle and it states"Every rifle is fired for group form in a bench rest.Acceptance specs call for 5-shot groups with an extreme spread of less than 3 inches at 100 yards.I can almost swear that all of the ones I have seen will do better than that.Like you stated earlier with serria bullets and handlods most definiately.

Post some pics of your build!

Molon, excellent report....as usual...

Molon, you shoot with irons as well as you do with a scope?



Here's my M16 upper build that I gave to my dad:

It depends upon the particular iron sights, but generally speaking, no.  For example with standard AR-15 sights, A2 front sight post and standard A2 size small rear aperture, about the best that I can do is 1.5 MOA.  The 10-shot group pictured below was fired from 50 yards while zeroing the BUISs on one of my AR-15s.

"Brand new" as in newly manufactured, or as in older barrels that have never been fired?

Molon, does your stock have the trapdoor butt plate? If not, it is an M16 stock also used on early Colt Sporters. The M16A1 stock has the trap door and cleaning kit recess.

I also found that  post a little hard to swallow

Hope Molon doesn't mind, but I'll jump in here.  That appears to be a Cav Arms A1 stock; modern materials, room for a trapdoor buttplate, and sling swivel that can be turned to the side.
Useful and sturdy, some of us aren't smitten with their looks.
Moon
ETA-
Don't let the retro guys hear what you're doing with NOS A1 barrels and uppers....there'll be blood on the tracks.
M

As regards A1 accuracy, an old target shows six shots into 0.855" at 50 yds.  
That's the first range trip for a NOS A1 upper using 55 grain ammo.
There was a -8* windchill, and I was so damn cold that I neglected to write down WHAT KIND of 55 grain ammo, but A1s shoot just fine.
Moon

Great write up and pics, Molon! And a nice rifle!

Good Stuff!

Great write up, I just love to read your posts.

Anyone know where to buy new 20" A1 barrels with a 1:12 twist?

-KW

I don't know when Colt started dating their barrels but the M4 14.5" 1:7 bbls are dated on the left side behind the handguard endcap.

CD

Awesome write-up. I always figured these barrels were capable of good accuracy, but never saw any solid figures until now.

I really need to float my A1 clone, but like the triangle handguards too much.

53vortec- put a nm free float tube on then the a1 handgurds on top of that

I've actually kicked that idea around, but wasn't sure how the thin A1 barrel would cope with the reduced ventilation.

I've said this before but the SAK barreled 1/12 A1 upper shot very very well with just a 4x scope on it.  Like the others said 1.5 MOA.  Makes you wonder why to even use a Hbar.  I guess when shooting high volumes it would help.

Correct . . . with the addition of a Colt butt-plate.

The extra weight of a NM free-float would kind of defeat the purpose of the light-weight barrel, no?

That too.

I'm a bit torn on this one; I built it as a retro piece for fun, but know I could get more accuracy and reduce issues from tight-sling positions by floating it.

Guess I need to find another light barrel.

That's the spirit!

The Cav buttplates are REALLY lame, especially compared to the stocks, which are well made and sturdy..  Good move.
I wish Cav would get rid of the sling swivel slot; they'd make a great retro A1 buttstock.
Moon

Ditto.

Trivia:  The Colt A1 beavertail handguards, handguard retainer ring, barrel nut, slip ring, spring and snap ring weigh 12.4 ounces.  The JP Enterprises handguard weighs 11.6 ounces.

You wouldn't happen to have a source for genuine Colt A1 buttstocks in good condition, would you?

I'm still looking for a source for a genuine Colt A1 buttstock in good condition if anyone knows of one.

I would guess that is the same Al Miller who still occasionally writes for Rifle and Handloader magazines.

I have always enjoyed his work.

Thank you for your post.  I am consistently amazed at how accurate a "rank and file" AR-15 can be.