Actions lie at the heart of a rifle, but sometimes they get the least attention. Bruce Thom, owner and founder of BAT Machine, recently joined me to discuss the development of the BAT Hammerhead action in collaboration with Unknown Munitions!
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About the BAT Hammerhead Action
The new Hammerhead action from BAT Machine features a shorter 75 degree bolt throw with different bolt stop options for different throw lengths. This was specifically requested by Unknown Munitions and brought to life!
It shares the same tenon print as the BAT Igniter and BAT Bumblebee which I have already chambered for, none of which have counterbore. (Bruce Thom and I proved counterbore is not necessary in this video, but do NOT try this at home.) This allows me to swap barrels between all three actions.
The Hammerhead comes with two bolt stops and a magazine stop for single-stack magazines. It has no trigger hanger and the bolt stop pin was moved to the side to simplify inletting. It is available in both right- and left-handed configurations. Thom explained that he modified the feed ramps and made considerable changes to the way the bolt operates. Current bolt face options include .385 (.223 Rem), .455 (PPC), .48 (Standard), and .55 (Magnum).
From BAT Machine:
Our Newest purpose built competition action. Faster operating than ever before with our renowned BAT Precision. Featuring a shorter 75 degree bolt lift that doesn’t compromise action strength or feel. The Hammerhead includes a standard length bolt stop or a short travel bolt stop for BR/Dasher length cartridges. The shorter position reduces travel by .350″ thus improving cycling speed. An adjustable and removable screw is fitted to the magazine port to allow for the use of AICS magazines without the feed-lips contacting the bolt. Our new Hammerhead action is designed to handle Magnum cartridges. Available from Unknown Munitions.
Features:
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- Remington 700 Short Action Footprint
- Integral 20 MOA Picatinny Rail and Recoil Lug
- 75 Degree Lift 2 Lug Bolt
- Comes with Two Bolt Stops: (Standard & .35″ reduced travel for BR/Dasher)
- Modular Bolt with Spiral Fluting and a Flat Face
- Action Weight is 34.6 oz
- Large (3.03″) Magazine Opening Cut for the Accuracy International AW (double stack double feed) Boxes.
- Adjustable stop to optimize use of AICS magazines
- Ejector Port Length is 2.55″ at Stock Level Tapers Back to 2.76″ Long at the Top.
- DLC Coated M-16 Style Extractor.
- Black Nitride Coated Body, Bolt, and Firing Pin
- Custom anodized aluminum knob with 5/16-24 thread.
- Barrel Tenon is 1.0625 x 18 tpi
The 75 degree bolt throw is ideal for PRS shooters but the Hammerhead is also a solid choice for high-end hunting rifles. I took the precision rifle route and built a 6mm x 47 Lapua around my Hammerhead.
Evolution
The BAT TR action was BAT Machine’s first venture into the tactical repeater space.
It wasn’t long before Bruce started thinking about how to make it better. The TR has counterbore to lengthen the barrel shank and allow for the bullet tip to jump into the chamber. This was designed to address feeding concerns with shorter cases—concerns that turned out to be unwarranted. Not including the counterbore in the Hammerhead made the bolt compatible with the Igniter, VR, Vesper S, and Bumblebee.
Also contentious was the decision not to include a trigger bracket. Though a bracket can make it slightly more convenient to change a trigger, most actions are going into chassis nowadays, which require removing the barreled action from the stock to change the trigger. Some stocks also require extra inletting to accommodate a trigger bracket. The BAT TR has a removable trigger bracket that allows the user to tune the firing pin fall. The number and variety of quality triggers currently on the market make this a non-issue.
Bruce heard a number of complaints from tactical shooters who had malfunctions from resting their center-feed magazine on obstacles or gripping it too tightly. In response, he incorporated an adjustable stop to prevent the magazine from hitting the bolt and jamming.
The new bolt stop allows for faster, smoother bolt cycling. Bruce reported that PRS competitor Corson Piper has been using the Hammerhead all season and has been extremely impressed by the shorter bolt stroke. BAT Machine also enlarged and strengthened the pivot pin and moved it to the top of the action.
The Hammerhead’s 75 degree bolt throw was one of the last design elements added. BAT Machine started out with great success in benchrest due to their non-standard bolt lug width. Bruce designed the lugs this way to better support cases with unequal head thickness and wanted to retain this lug contact while shortening the bolt lift. 75 degrees was the magic number while retaining 100% contact.
BAT Machine has expanded this change across their line. The Bumblebee, Vesper S, and Igniter actions now all have 75 degree bolt lift.
Conclusion
BAT Machine’s new Hammerhead action features improvements over their popular TR action. Most obvious is the new 75 degree bolt lift for faster cycling, a feature BAT Machine has extended to their Bumblebee, Vesper S, and Igniter actions.
The Hammerhead was designed with competitive shooters in mind, but can be used in a variety of scenarios. It also retails for the same price as the TR. Stay tuned for a 6.5 Creedmoor build featuring a Hammerhead action and Foundation Samson PRS stock.
Get the Gear
Purchase the BAT Hammerhead Action at Unknown Munitions! (BAT Machine’s Authorized Hammerhead Dealer)
View all BAT Machine actions here!
If you are interested in building your own precision rifles, be sure to check out the Colorado School of Trades.
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Thanks,
Gavin Gear