Ultradyne Lightweight Butt Stock – Ultimate Reloader


From its inception, .308 Shorty has been a compact all-around rifle. Earlier this year we swapped out a Foundation Stock for the Ultradyne UD3 chassis. This time we’re adding more versatility with the Ultradyne UD lightweight butt stock


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About the UD Lightweight Butt Stock

Shorty has been wearing a collapsible M4-style butt stock since we placed the action in the UD chassis.

This stock isn’t ergonomic, is a bit wobbly, and has no buttpad. The new UD lightweight butt stock from Ultradyne seems almost purpose-built for Shorty.

It weighs 14 ounces and has an adjustable length of pull from 13” to 14”. It’s also designed to be simple and silent — no rattling once secured. The cheek piece isn’t adjustable but comes in three options — low, medium, and high — to match your scope rings. 

From Ultradyne

Introducing the UD Lightweight Butt Stock, crafted from solid 6061 T6 aluminum for optimal balance between weight and strength. Engineered for lightweight rifle builds without compromising durability. Adjustable in Length of Pull (LOP) from 13″ to 14″ with removable spacers, and three options for cheek heights, it offers tailored comfort to nearly any shooter. Additional spacers and separate cheek pieces are readily available for purchase if needed, ensuring a personalized fit. Regardless of spacer configuration out to four spacers, installation remains seamless, utilizing the same screws for all orientations.

Designed with user comfort in mind, it features an ergonomic cheek piece and a QD sling interface, catering to practical needs while remaining comfortable. Weighing in at just .875 pounds, the Lightweight Butt Stock enhances your rifle’s aesthetics with it’s sleek, one-piece design while minimizing additional weight. A bag rider is also available to purchase for enhanced stability.

With ten cerakote colors to choose from, matching this butt stock to the UD Chassis is effortless, allowing for a cohesive, personalized look. Achieve weights as low as 1.9 pounds when paired with the UD Chassis. The butt stock is equipped with the Ultradyne recoil pad for enhanced user experience, and installation remains effortless even when adjusting spacer configurations. Being compatible with any Mil-Spec buffer tube interface allows installation to be hassle-free with the provided castle nut.

What’s in the Box

The stock comes in custom packaging with stickers, an optional bag rider, and two length of pull spacers. 


I mounted the bag rider first, tightening each of the four screws individually before torquing them all down.

Next I removed Shorty’s grip for easier access to the indexing set screw and loosened the castle nut using a Wheeler castle nut wrench.

From here I unscrewed the M4 buttstock and added the Ultradyne, paying attention to proper indexing.

There was an immediate difference in the heft and feel of the stocks. The final step was to reattach the grip.

I did some dry firing, quickly realized the length of pull was a little short for my long frame, and added both extra spacers.

(Ultradyne designed this stock so that the same screws are used with two spacers as with four.) 

In the Field

This is a much more comfortable and appealing combination than the original polymer stock.

I had a Leupold Mark 5HD 2-10 x 30 installed on the barreled action and paired Shorty with .308 subsonic loads for some steel target fun. These affordable loads featured 220 grain Berry’s plated bullets and Hodgdon’s Trailboss. 


This lightweight butt stock was a welcome addition to our UD3 .308 Shorty setup.

Simple and practical, the bag rider and length of pull spacers are easy to add and remove to fit your needs. Though you don’t have to pair this stock with the UD chassis, this platform  is available in varying lengths, all of which include Dynalock

Get the Gear

Ultradyne UD Lightweight Butt Stock

Order and customize your UD Chassis from UltradyneUSA.com.

BAT Igniter Action

Leupold Mark 5HD 2-10×30

Berry’s 300 Blackout 220 Grain Bullets

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Gavin Gear

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