Loading .375 CheyTac on the Forster Co-Ax XL – Ultimate Reloader


Reloading a massive cartridge like .375 CheyTac takes special supplies. Today I start my reloading journey for my .375 CheyTac build with the Forster Co-Ax XL!


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About the Build

I recently showed the evolution of my new ELR rifle in .375 CheyTac, built off my .50 BMG Incredible Hulk rifle.

This build is designed for ELR competition, something I’m looking forward to learning under the mentorship of King of 1 Mile and King of 2 Mile Paul Phillips!

Paul Phillips, King of 2 Mile

(His friend and fellow King of 1 Mile, Clay Rhoden, will also be assisting.)

This rifle build is centered around a BAT EX action (with a .375 bolt) and a Bartlein barrel cut to Paul Phillips’ specifications.

It also has a Timney 502B benchrest trigger in an Accurate Rifle Systems ELR chassis with a BipodeXt extension I paired with an Accu-Tac bipod.

About the Reloading Set-Up

At the heart of my loading set-up is the new Forster Co-Ax XL single-stage press, designed with extra travel to accommodate large cartridges like the .375 CheyTac.

I am pairing it with a Forster two-die set including the Forster Ultra Micrometer seating die.

Though the Primal Rights Competition Primer Seater accepts shellholders from popular brands like Frankford Arsenal,  I still had a hard time finding a .375 CheyTac shellholder.

I talked with the owner of Primal Rights and he apprised me of a collaboration between Primal Rights and Graf & Sons to produce this very thing. I also have the new Forster XL comparator.

This is ideal for getting base to ogive measurements and accepts a variety of different inserts starting with .338. For load specifics, I once again turned to Paul Phillips who directed me to Cutting Edge Monolithic LZR .375 400 Max Gen 2 copper bullets, Peterson Brass, and Hodgdon H50BMG. 

Loading .375 CheyTac

With a  loctite dummy cartridge for overall length handy, I took a piece of brand new Peterson brass and primed it on the Primal Rights competition primer seater.

Using the AutoTrickler V4, I dispensed 142.0 grains of H50BMG. Do NOT use this load data without consulting several manuals and working up to it yourself.

I noticed while loading for .50 BMG that the AutoTrickler V4 has a tendency to run a little over the desired charge, so I set it a bit under and manually add granules until I reach it.

The charge for .375 CheyTac is so large that I had to use a small plastic cup instead of a traditional pan.

During this process I quickly realized I’m missing a few other tools that I plan to talk to Creedmoor Sports about, namely a loading block and a better-suited funnel. 

I’m not sizing the unfired brass, so I skipped ahead to seating the bullet with the ultra micrometer seating die.

After loading about six rounds, I headed out to the range to test them. 

Though the .375 CheyTac is intended for shooting out to two miles, I still started at the standard 100 yards with the LR-3 setup.

One of my three-shot groups measured just under half an inch.

This came after I raised the bipod and buttstock and used ammunition I had loaded 0.022” longer overall length. (I verified this using the Forster XL comparator with eight-inch calipers. 

Measurement Difference Compared to the Dummy Round

I look forward to seeing what this rifle can do after more load development and coaching! 


Though very early in my ELR journey, I’m especially happy with how my custom rifle and ammunition have been performing. Looking forward, I’ll be fine-tuning the load to my rifle and sizing once-fired brass. The Forster Co-Ax XL was very easy to use and is purpose-built for accommodating ELR cartridges. Needless to say, I also need a lot of practice! 

Get the Gear

Forster Co-Ax XL at Creedmoor Sports

Forster Ultra Micrometer Seater Die at Creedmoor Sports

Forster XL Comparator 

Forster .375 CheyTac Ultra Die Set XL

Satern Anti-Static Powder Funnel at Creedmoor Sports

CheyTac Loading Block at Creedmoor Sports 

Hodgdon H50BMG at Midsouth Shooters Supply

Primal Rights/Graf & Sons .375 Shellholder 

Cutting Edge Bullets: LZR .375 400 Max Gen2

.375 CheyTac Peterson Brass at Creedmoor Sports

Primal Rights Competition Primer Seater


Longshot Ranger

Longshot LR-3

Accu-Tac Bipods

Garmin Xero C1 Pro at Creedmoor Sports and Midsouth Shooters Supply

Global Precision Group

Want to build a rifle like this? Check out the Colorado School of Trades and OTM Tactical (UR5 to save 5%!) for barrel blanks and other supplies. 

BAT EX Action 

Accurate Rifle Systems ELR Chassis 

Accuracy Solutions BipodeXt

APA Gen 2 XXX Bastard brake

Bartlein Barrels

Precision Matthews TL-1660

Timney 502B Remington 700 Benchrest Trigger at Midsouth Shooters Supply

Ultimate Reloader Rifles

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Gavin Gear

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