TRIARC Track 2.0 Accuracy

[Molon]

TRIARC 16” Track 2.0 Barrel Accuracy Evaluation

Over the last several years we’ve seen barrel manufacturers starting to move away from the traditional barrel profiles found on AR-15 barrels, such as the government profile, and moving toward “enhanced” barrel profiles, with the specific objectives of balancing weight distribution and handling characteristics while endeavoring to maintain accuracy that is on par with barrels with heavier profiles. The late John Noveske was the impetus for bringing modern AR-15 barrel profiles to the civilian market. His 16" CHF N4 barrel profile has the same weight as a government profile barrel of the same length, but it has a more intelligently designed contour that places more of the weight of the barrel from the chamber to the gas block journal and does away with the M203 cut-outs.

TRIARC is now producing a 16” barrel that has a profile that is quite similar to the Noveske N4 profile. TRIARC calls this their Track 2.0 barrel and they refer to the barrel profile as the “balanced straight contour.”

TRIARC 16” Track 2.0 . . .

Noveske 16” N4 . . .

The TRIARC 16” Track 2.0 barrel is made from 4150V Milspec B-1159E Chromium-Molybdenum-Vanadium steel and has a nitride finish. This stripped 16” barrel has a weight of 1 pound, 13.1 ounces. For comparison, a stripped 16” Colt 6920 government profile barrel has a weight of 1 pound, 12 ounces. The barrel extension on the Track 2.0 barrel has M4 feed-ramps and is coated with NP3.

The gas block journal of the Track 2.0 barrel has a diameter of 0.75”; 0.7497” to be exact. The gas block journal comes with a single dimple contralateral to the gas port. Speaking of the gas port, it has a diameter 0.0695”. Unlike the gas block journal of the Noveske N4 barrel, the gas block journal of the Track 2.0 barrel has a length of 1”; so a traditional A-frame front sight base will not work with this barrel.

The TRIARC 16” Track 2.0 barrel has a 5.56mm NATO chamber, a 1:7” rifling twist and utilizes a mid-length gas system. A Colt reference bolt closed on the chamber with a 1.4646" head-space gauge and did not close on a 1.4666" head-space gauge. Further chamber checks using both factory loaded ammunition and hand-loads detected no defects in the neck or throat of the chamber.

The Track 2.0 barrel is button rifled and the bore is honed using Sunnen machinery. This honing system not only produces a “glass-smooth” finish to the interior of the bore, it also helps to create tight tolerances for the inside diameter of the bore throughout the entire length of the barrel.

The type of rifling found on the TRIARC Track 2.0 barrel is rather unique for AR-15 barrels. The rifling is known as single edge polygonal rifling (SEPR). The patent for this type of rifling (as well as a patent for machinery used to manufacture this rifling) is held by F.J. Feddersen. With single edge polygonal rifling, one side of the land has a traditional squared edge, while the other side of the land has a polygonal edge.

The F.J Feddersen patent for SEPR states that this type of rifling produces less bullet deformation than traditional rifling. F.J. Feddersen also claims that this rifling significantly reduces escaping gases and loss of gas pressures.

I've decided that I'm going to use an SOLG upper receiver for this build. It will be a nice thermal fit with the barrel extension of the TRIARC barrel. The internal specs of the upper receiver mate perfectly with the TRIARC bolt carrier group.

The stripped Sons of Liberty Gun Works upper receiver was filled-out with a Forward Controls Design low drag forward assist and V7 Weapons Systems’ ejection port cover and one-piece port cover rod.

I recently picked-up an SOLGW stripped lower receiver to go with this upper receiver group. The fit is damn near perfect.

....


TRIARC Bolt Carrier Group

For some time now I’ve been interested in trialing a bolt carrier group that has been coated with NP3 (electroless nickel TEFLON). NP3 has attributes that are potentially beneficial to the reciprocating parts of the AR-15 such as the bolt and bolt carrier and TRIARC Systems sells just such a bolt carrier group.

The TRIARC bolt carrier weighs the exact same amount as a full-auto Colt bolt carrier; 9.4 ounces. The carrier proper is made from case hardened 8620 steel, while the gas key is made from 4140 steel. The gas key is fastened to the carrier using Grade 8 hardware. The aft section of the bolt carrier has a small radius on the external diameter to aide in the smooth entrance of the bolt carrier into the receiver extension/buffer tube

The staking on the gas key is nicely done.

The NP3 coating on the bolt carrier gives the carrier the most lubricious feel of any bolt carrier that I’ve owned; including my JP Enterprises bolt carriers.

The length of the TRIARC bolt carrier is 6.672”, which meets the US mil-spec. The internal diameter of the gas key is 0.181”, which also meets the US mil-spec.

The bore of an AR-15 bolt carrier can be thought of as being divided into three different sections with critical dimensions. Starting at the front of the carrier, the “bolt run” section of the bolt carrier interfaces with the “land” on the bolt. This section of the Triarc carrier has an internal diameter of 0.531”, which as before, meets the US mil-spec.

The next two sections of the bore of the AR-15 bolt carrier are extremely important for the proper function of the gas system. The gas system of the AR-15 is commonly referred to as a “direct impingement” system. In actuality, the AR-15 uses a gas piston system with the tail of the bolt and the gas ring section being the piston and the two sections of the bore of the bolt carrier being discussed forming the cylinder.

The second section of the bore of the bolt carrier interfaces with the gas rings on the bolt and this section of the TRIARC bolt carrier has an internal diameter 0.4995”. The third section of the bolt carrier interfaces with the tail of the bolt and this section of the TRIARC bolt carrier has an internal diameter of 0.2515”. Both of these dimensions meet the US mil-spec and when combined with a bolt with the proper dimensions should produce a highly efficiently functioning gas system.

The TRIARC bolt is “machined from case hardened 9310 steel then shot-peened, heat treated” and magnetic particle inspected. I checked the firing pin protrusion on the TRIARC. With the supplied firing pin, the protrusion was 0.0295". With a new Colt firing pin the protrusion was 0.0290". I also checked the headspace of the TRIARC bolt with the 16" TRIARC Track 2.0 barrel. The bolt closed on 1.4646" head-space gauge and did not close on a 1.4666" gauge.

The mil-spec for the inside diameter of the bolt face is .380", with a tolerance of plus .005". The inside diameter of the bolt face of the TRIARC bolt that I received is ~0.3825".

It is interesting to note that the cam pin hole on the TRIARC bolt does not have relief cuts like a Colt bolt. Neither does a Hodge bolt.

continued in the next post

 

[Molon]

ZEV 14 5/8” Wedge Lock Handguard


When I first picked-up the ZEV handguard, I immediately noticed the distinctive color and smooth and lustrous finish. The ZEV handguard has a velvety, luxurious look that feels so good in the hand. The ZEV handguard is sure to stand out on the firing line.

The US patent for the wedge lock mechanism employed in the ZEV Wedge Lock Handguard states that it was invented by Michael Miller and James Reid. The patent was originally granted to Mega Arms and has more recently been transferred to ZEV Technologies.

The wedge lock mechanism that secures the ZEV M-LOK handguard to the ZEV barrel nut is a simple, yet elegant approach to fastening a handguard to an upper receiver. Speaking of the barrel nut, the ZEV barrel nut is a hefty 3.6 ounces of finely machined stainless steel. The ZEV handguard comes with a custom barrel nut wrench.

The ZEV wedge lock assembly sits in a bottom lip of the ZEV handguard. The slim design of the wedge lock assembly allows for a sleek, streamlined handguard profile when compared to some of the more bulbous designs on the market.

The wedge lock assembly consists of a top wedge and a bottom wedge with a Torx bolt sandwiched in between them.

The top of the top wedge has a concave shape that perfectly matches the curvature of the barrel nut. The top wedge and the bottom wedge are mated at an angle such that when the Torx bolt is tightened, the top wedge is pulled rearward and upward wedging itself between the barrel nut and the bottom wedge and handguard forming an extremely solid lock-up.


The top wedge prior to being tightened . . .

. . . and after being tightened . . .

The ZEV Wedge Lock handguard used for this build is the 14 5/8” version and it’s manufactured from 6061 aluminum. The handguard, barrel nut and mounting hardware have a combined weight of 15.5 ounces.

The ZEV handguard has an indexing/anti-rotation pin at the 12 o’clock position. The hole in the ZEV handguard has an interference fit with the anti-rotation pin and mates precisely with the anti-rotation hole in the SOLGW upper receiver. The ZEV handguard also employs two anti-movement set screws at approximately the 04:00 and 07:00 positions.

The installed ZEV Wedge Lock handguard had zero degrees of rotation referenced to the picatinny rail of the upper receiver.

When selecting a gas-block to use with an M-LOK hand-guard, you’ll want to pay particular attention to the inside diameter of the hand-guard and the outside dimensions of the gas block. You don’t want to make the amateur mistake of installing a MK12 gas block under an M-LOK hand-guard that doesn’t have appropriate clearance for that gas-block. For this build, I used a V Seven Weapons Systems 17-4 PH stainless steel, set-screw, low-profile gas-block with an IonBond finish.

The TRIARC 16” Track 2.0 barrel was thermal-fitted to the SOLGW upper. Next, the ZEV wedge-lock handguard and the V Seven gas block were installed. With the TRIARC NP3 bolt carrier group in place and the upper receiver group mated with the SOLGW lower receiver group, the rifle passed dry-fire safety/function testing.


TRIARC has stated that the diameter of the gas port (0.0695”) on this barrel was designed with the use of the Vltor A5 buffer system in mind and they recommend using an A5-H1 buffer. So, I began live-fire function testing with the A5-H1 buffer and a new Colt rifle length spring in a Vltor A5 buffer tube. The weapon cycled smoothly with both 223 Remington hand-loads and factory-loaded 5.56mm loads; with the bolt locking-back on the last round of the magazine every time.


I also tested the upper receiver group mated with a lower receiver group that has a standard rifle length buffer system using a standard Colt rifle buffer and rifle spring. Again, the weapon cycled smoothly with all loads tested and there were zero malfunctions.

continued in the next post . . .

 

[Molon]

Accuracy

Prior to conducting the accuracy/precision testing of the TRIARC Track 2.0 barrel, I fired a total of 120 rounds of various loads through the rifle. There were no malfunctions of any kind. The barrel and upper receiver group were then thoroughly cleaned and lubricated.

The ammunition used for the formal accuracy evaluation was one of my standard match-grade hand-loads topped with the Sierra 55 grain BlitzKing. This load has produced ½ MOA 10-shot groups when fired from my Krieger barreled AR-15s.

I conducted an accuracy (technically, precision) evaluation of the 16” TRIARC Track 2.0 barrel from my bench-rest set-up following my usual protocol. This accuracy evaluation used statistically significant shot-group sizes and every single shot in a fired group was included in the measurements. There was absolutely no use of any group reduction techniques (e.g. fliers, target movement, Butterfly Shots).

The shooting set-up will be described in detail below. As many of the significant variables as was practicable were controlled for. Pictures of shot-groups are posted for documentation.

All shooting was conducted from a concrete bench-rest from a distance of 100 yards (confirmed with a laser rangefinder.) The free-float hand-guard of the rifle rested in a Sinclair Windage Benchrest, while the stock of the rifle rested in a Protektor bunny-ear rear bag. Sighting was accomplished via a Leupold VARI-X III set at 25X magnification and adjusted to be parallax-free at 100 yards. A mirage shade was used. Wind conditions on the shooting range were continuously monitored using a Wind Probe. The set-up was very similar to that pictured below.

The Wind Probe . . .

Six 10-shot groups of the match-grade hand-load were fired in a row from the TRIARC Track 2.0 barrel from a distance of 100 yards. Those groups had the following extreme spreads:

0.82”
0.80”
0.79”
1.08”
0.87”
0.88”

for a 10-shot group average extreme spread of 0.87”. The six 10-shot groups were over-layed on each other to form a 60-shot composite group. The mean radius for the 60-shot composite group is 0.28”



The smallest 10-shot group . . .

The 60-shot composite group . . .

Lastly, for any Internet Commandos in the viewing audience today, here’s a pic of a sub ½ MOA group fired from the TRIARC barrel from 100 yards. The group has an extreme spread of 0.49 MOA.

….

 

[Near miss]

It seems that any quality barrel nowdays are below 1moa average? What is your experience, could you estimate price categories per moa tenths?

For me after roughly 0.8moa my main concern is barrel durability (=chrome-lining).

I do enjoy the thought of having a true match barrel, always after shooting a bolt gun I feel a bit empty returning to AR and ~1moa. But ofc, in practice there is very little difference to hitting far targets between those precision levels.

 

[gxer]

Thanks for the write up! Interested to know if the SEPR gives this barrel a higher muzzle velocity compared to a traditional barrel of the same length.

 

[bfoosh006]

Great write up, and great read for a Sunday !

That 60 shot composite is "food for my soul".

 

[Molon]

Thanks for the write up! Interested to know if the SEPR gives this barrel a higher muzzle velocity compared to a traditional barrel of the same length.

I had planned on doing a velocity comparison to a 16" Geissele barrel, but as the Geissele barrel that I purchased won't even chamber a round, I wasn't able to do that test.

....

 

[CrooksNbigBeaver]

Thanks for the writeup, good stuff as always

That basically lines up exactly with what I have found with my 12.5 over the last few months. Runs as well as any barrel ive had(A5H1), shoots soft with a reasonable amount of suppressed blowback, and with 23.5gn 8208 + 77smks, I call it a 3/4moa barrel. Pretty much exactly what i was looking for from a reasonably priced nitride.

One thing of note. I was seeing slight ejector swipes with XBR loads that showed no pressure signs in my CLE wylde chambered Bartleins, running the same bolts. Doesnt really mean anything all that specific, just something to look out for. Still well within reasonable levels.

Cant really comment on the velocity difference, as i dont have any other 12.5 barrels unfortunately. Will post back when i have more concrete numbers, once my magneto gets fixed.

Overall would definitely recommend for the ~$250 I paid

 

[CrooksNbigBeaver]

Just a slight add to something Molon commented on. This extension was right on the border of being a thermal fit with an ADM upper. I reckon you could get it in with a little persuasion, but thermal fitting was more appropriate.

 

[Runcibleman]

I installed mine that I got at a pretty good sale from Primary Arms last year into a Mega upper, and man, did it need a good bit of heating of the upper and even a little chilling of the extension before I could fit the barrel into the upper! I guess a tight fit is generally considered high desirable though...