Custom 6.5 Creedmoor: WOOX Cobra + Tikka T3x

You all have asked for more Tikka T3x content, so it’s time for a full Tikka T3x build! WOOX’s Cobra stock is one I haven’t tried yet and their first thumbhole offering. (Use code ULTIMATERELOADER10 to save 10% at WOOX.) I’m combining this with the Tikka T3x action and a barrel from Carbon Six for a lightweight 6.5 Creedmoor!

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Bill of Materials

In addition to the WOOX Cobra, I have a .308 Tikka T3x barreled action with an upgraded trigger: a Bix’n Andy Dakota from Bullet Central.

I will be chambering the 6.5mm Carbon Six barrel on the PM-1340GT using a custom reamer with specs from Dave Manson.

This barrel is the first I’ve worked with featuring Carbon Six’s ECM, electrochemical machining process.

A full-length ARCA rail and Element Theos in Hawkins Precision rings will round out the build.

About the WOOX Cobra

The WOOX Cobra is available in both walnut and tiger wood laminate with anodized aluminum.

Though I opted for tiger wood, both share incredible craftsmanship and attention to detail.

The length of pull spacers do not come installed, but I plan to add all of them.

From WOOX:

Ergonomically designed thumbhole stock that provides exceptional grip and control for precision shooting.

Cobra is breathtaking thumbhole precision stock specifically designed for precision shooters and long-range hunters who prefer the unique ergonomics the style provides. WOOX’ approach to creating its first thumbhole stock takes advantage of the unique comfort and control characteristics that can only be had with genuine wood. When combined with WOOX’s modular chassis, the result is nothing short of amazing: increased comfort, a steady shooting platform, and consistent shot-to-shot sub-MOA accuracy. Proudly made in Italy and USA.

Specifications:

- Installation: Drop-in. Does not require pillars or extra bedding.
- No gunsmithing required.
- Grip: Ambidextrous
- Chassis: AA 7075 aircraft-grade aluminum, hard anodized.
- Stocks: American Walnut, Laminated
- LOP: 13.5” – 14” (spacers included)
- OAL: 32”
- Weight: 3.5-4 pounds
- Max Floating Barrel:
  - Remington 700 models: 1.17”
  - Savage LA models: 1.15”
  - Sauer 100 models: 1.10”
  - Tikka, Ruger, Howa, Weatherby, CZ, Savage SA models: 0.95”
- Colors: Walnut, Tiger Wood

Planning

The first step was to remove the factory Tikka barrel from the T3x action.

I have heard horror stories about removing Tikka barrels and this one was no exception.

The magic touch was using a PR Precision Tikka action wrench from Canada along with a significant extension and Short Action Customs Bravo barrel vise.

Nothing else would make it budge!

Removing the barrel allowed me to take some measurements.

The Tikka barrel tenon has long been a subject of controversy and ambiguity online. I did a detailed analysis and produced the tenon print below which has never existed online before: (click to enlarge)

About the Precision Matthews PM-1340GT

The Precision Matthews PM-1340GT is a great gunsmithing lathe, with the following stand-out features at an affordable price:

All Taiwanese built with Japanese spindle bearings
1.5625″ thru-spindle capacity
Geared head
Inch and Metric thread cutting ability
13” Swing, 40” Between Centers
D1-4 Chuck Mount
MT3 Tailstock Taper

If you’d like to know more about the PM-1340GT, check out our full overview HERE.

Looking for more?

Machining

I always follow a chambering checklist to ensure I do not miss any steps.

As I dialed in the barrel on the PM-1340GT, it was apparent just how consistent the rifling was on the Carbon Six ECM barrel.

This was my third barrel chambering on the PM-1340GT, which I’ve made a variety of upgrades to. Working with the smaller lathe, I also opted to part the barrel on the PM-712G bandsaw.

I measured the action, installed the barrel in the lathe, indicated to 0.05”, pre-drilled the chamber, indicated to 0.001” in the throat, single-point reamed the pre-drilled area true, checked runout, reamed off the lands in the neck area, turned the tenon and thread relief, and threaded the tenon.

I did not have to clock the barrel as the barrel didn’t have to tilt, another sign of quality craftsmanship.

Next came cutting the bulk of the chamber. (The design of the Tikka system means no counterbore.) To check headspace, I use a machined ring that slips over the threaded portion, insert a go gauge, and measure with a depth micrometer.

Installing Spacer to Check with Depth Micrometer

I use software to assess this measurement.

Finally, I chamfered the chamber entrance and checked the 0.2 line reference area with a pin gauge. (This ensures the base of the chamber is not oversized.)

It’s important to note when doing machining work around a Tikka T3 or T3x that there is a chamfer on the front edge of the receiver. You can turn down a straight section and come off with a chamfer to give a blending effect. I chose to make a chamfer and have them both meet. This is really an aesthetic decision.

I flipped the barrel in the lathe and performed a traditional muzzle-threading job.

Assembly

I secured the barrel back into the vise and used a SAC internal action wrench (modular) to torque on the receiver.

The headspace was perfect, so I continued on to stock mounting.

The WOOX Cobra utilizes the original Tikka T3x bottom metal and magazine—no need to buy anything extra.

I added a full-length ARCA rail for convenient bench and tripod shooting and 3D printed a cover for the rear Picatinny rail.

For an optic I chose one of my favorites: the Element Optics Theos 6-36x x 56.

I did have to add a Picatinny rail for greater clearance as the Hawkins Precision integral ring mounts I had were not tall enough.

I also added an Area 419 Hellfire adapter and muzzle brake.

Shooting

One of the great things about 6.5 Creedmoor is that it is my “standard” long range caliber so I have a lot of different ammunition for it.

I was not happy with the one plus MOA groups I was getting. I was seeing this with Berger 140 grain factory ammunition, Hornady 147 grain ELD-M PRS load and 135 grain A-Tips.