Skeletonized Lightweight Hunting Action: BAT Vesper Overview

This time my trip to BAT Machine involved an in depth discussion with Bruce on Vesper! Vesper is BAT’s skeletonized lightweight hunting action. In this video we go over the specs and features, talk about its origin, applications, and more. Check it out!

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About the BAT Vesper

BAT Machine’s Vesper (Latin for Bat) is a lightweight hunting action with a modular bolt and skeletonized design available in short, medium, and long action for left- and right-handed shooters.

Both the original Vesper (long action repeater) and Vesper M (medium action repeater) are based on the BAT HR and have 90-degree bolt throws. The Vesper S short action repeater is based on the VR with a two-lug 75-degree bolt throw. All three models have an integral recoil lug, modified 20 MOA Picatinny style rail, 0.070” diameter firing pin tip, and modular flat-faced bolt with spiral fluting.

All Vesper actions are available exclusively from Unknown Munitions and built to the same exacting standards as BAT’s benchrest actions but with a bit more clearance on the bolt for improved performance in dirty conditions.

BAT also ensured that all three Vesper actions have the longest magazine cut available from any manufacturer – no need to notch feed ramps for long cartridges!

Showcasing Longer Load Port, Custom DBM from Unknown Munitions

Unknown Munitions also offers a detachable bottom metal magazine system that maximizes length.

From BAT Machine:

It has a modular bolt that allows for lower cost bolt face changes. Built with our proven .070″ diameter firing pin tip for maximum accuracy and reliable ignition. Current versions are not compatible with our BAT Picatinny Rings or any other two pin style ring.

Vesper S Specifics:

- Weight: 24.8 ounces
- Bolt Faces: .385 (223 Rem), .455 (PPC), .48 (Standard), .55 (Magnum)
- Right or Left Hand Bolt

Vesper M Specifics:

- Weight: 25 ounces
- Bolt Faces: .485 (Standard), .55 (Magnum), and .60 (338 Lapua)
- Right or Left Hand Bolt

Vesper Specifics:

- Weight: 26 ounces
- Bolt Faces: .485 (Standard), .55 (Mag), and .60 (338 Lapua)
- Right or Left Hand Bolt

My 7 Sherman Short Build and Key Considerations

I centered my 7mm SS short action build around the BAT Machine Vesper S in the Ezekiel Hybrid Hunter from Foundation Stocks.

I chambered a thinner profile 7mm barrel blank from Custom Rifle Barrels on my Precision Matthews PM-1440HVT-2 Lathe using a Manson Precision reamer.

Pulling it all together is a Hawkins Precision M5 DBM with .300 WSM three-round mag, Bix’n Andy Dakota Trigger from Bullet Central, and Leupold Mark 4HD 6-24×52.

Bruce Thom mentioned that if you aren’t ordering a stock/chassis specifically inletted for a BAT Vesper you need to consider the length of the ejection port, bolt stop location, and barrel shank diameter.

The Vesper S takes a minimum 1.2” diameter barrel shank while the medium and long actions take a minimum of 1.25” barrel shank.

REM 700 Trigger (Bix’n Andy Dakota) Install on BAT Machine Vesper S

While the Vesper and Vesper S are based on the REM 700 footprint, the Vesper M medium-action follows the same medium action specifications other custom action manufacturers are following. You also need to decide if you want to take full advantage of the Vesper’s extended magazine cutout.

Origins of BAT Vesper

Vesper grew out of BAT’s lightweight, aluminum hunting action. This model had a flat base that wasn’t compatible with all existing stocks and chassis.

Seeking to make things easier and simpler for customers, BAT Machine created a steel version (Vesper) that retained the same quality and rigidity of the aluminum inspiration.

Bruce Thom explained that the skeletonization on the Vesper doesn’t go all the way through to retain rigidity and prevent debris from getting into the action. For the same reason, Bruce chose to put holes in the recoil lug rather than pocket it. This small design detail results in a more rigid structure to take recoil without flexing.

The 75-degree bolt throw on the Vesper S came directly from Hammerhead and that action’s success in competition. This shorter throw allows for faster follow-up shots and greater scope clearance. All Vesper actions are 100% 17-4 stainless and heat treated with Black Nitride.

Conclusion

Bruce Thom and his team at BAT Machine put considerable thought into every element of the BAT Vesper, taking their own designs as inspiration and optimizing them for hunting and accessory compatibility. Next up for us is a 7mm PRC in a medium action for optimized mechanics!