Ultradyne UD7 7mm PRC Long Action

Ultradyne offers a number of combinations of their UD chassis. We’ve looked at the UD3, UD5, and UD7 chassis, all named for the number of M-LOK slots on the side of the forend. This time we’re looking at the UD7 again, but the long action version. 

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About the Ultradyne UD7 Chassis

The UD Chassis system is a versatile yet affordable option to transform a rifle with a traditional stock to something with ARCA, Dynalock, and M-LOK compatibility. Go to Ultradyne USA for a full list of inlets.

From Ultradyne USA:

The Ultradyne Chassis is crafted from a solid bar of 6061 T6 Aircraft Aluminum for exceptional strength and durability. The one-piece design weighs between 1.1 and 1.3 pounds, depending on the model. This makes it suitable for both hunting rifles that weigh as little as 6 pounds and long range target rifles that weigh up to 16 pounds. When paired with the Ultradyne Adjustable Butt Stock, it is lighter than most factory stocks yet has the ability to add up to 5 pounds with optional weights.

The Ultradyne Chassis is packed with features including an adjustable magazine release lever, compatibility with AICS magazines, ability to work with any Mil-Spec butt stock, a built-in Arca rail, M-LOK slots on three sides, and Dynalock technology to ensure a secure fit. The action is held in place with V-channel bedding that can accommodate free-floated barrels up to 1.35 inches in diameter.

General:

    • 6061 T6 Aluminum
    • Cerakote Finish
    • Butt stock Interface: Mil Spec
    • Grip Interface: Mil Spec A2
    • Magazine Interface: AICS
    • 1.35” Max. Barrel Diameter

UD7:

    • 21 oz
    • 18.5” length, 10.8” Arca Length
    • 20 M-LOK Slots

About the Rifle

My 7mm PRC Freedom Rifle build centered around a BAT HR (long action) with magnum bolt face bolt and 28” Bartlein barrel, complete with custom Cerakote and laser engraving. I originally had it set in a chassis that wasn’t full-length ARCA capable, so the UD7 with UD spigot (extra 3.25” of ARCA) will be a nice upgrade. This rifle also has a Bix’n Andy Remington 700 TacSport trigger installed. 

Transformation

I decided to pair the UD7 coyote tan chassis with a matching UD adjustable buttstock, borrowing it from my UD5 22 ARC. I also added a vertical rubber grip. I removed the barreled action from the existing chassis and secured it to the UD7 complete with spigot, buttstock, and grip. (It’s easier to fully prepare the stock and chassis before adding the barreled action.) 

Once I had the full rifle assembled, I mounted a Athlon Midas TAC 5-25×56 and added a .30 caliber EC Tuner brake

Shooting

I began with boresighting, a usually simple process that gave me a bit of trouble this time around. Shooting center of the paper revealed no impacts, so I fired a shot at the top of the paper, right side, bottom, and left side, checking for holes each time. It turned out I was 6 ½ inches off the right side, but with near perfect elevation. I made my corrections for a proper zero and proceeded to shoot a group with my new load: virgin ADG 7mm PRC brass, 180 grain Hornady ELD-M bullets, 66.4 grains of Retumbo, and magnum large rifle primers. Five shots at 100 yards measured 0.714”, under ¾ MOA. This is without adjusting the EC Tuner brake and limited practice with this gun. 

Conclusion

The 7mm PRC is the best-shooting magnum cartridge I’ve had experience with—an ideal combination of precision and recoil. Adding the UD7 with full-length ARCA rail made it even better, with the spigot providing more room for bipod balance adjustments. 

Get the Gear

Order and customize your UD Chassis from UltradyneUSA.com.

UD Adjustable Buttstock

UD ARCA Dynalock Rail 

UD Spigot

Bat HR Action (Long Action) with magnum bolt face bolt

Athlon Midas TAC 5-25×56 FFP Scope

Bix’n Andy Triggers are available exclusively from Bullet Central.

Bartlein 7mm 5R Barrel Blank 1:8

EC Tuner Brake

 ADG Brass

Hornady 180 grain ELD-M Bullets at Midsouth Shooters Supply

Hodgdon Retumbo at Midsouth Shooters Supply

Longshot Hawk

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Thanks,
Gavin Gear

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