If you’ve desired to get acquainted with the 6mm/.223 cartridge, good for you! You are definitely a wildcat! Recently the team at Craig’s Outdoor Sports tested a custom built Remington 700, chambered in 6mm/.223 also designated as the 6×45 caliber.

Parts used in this build included:

• Remington 700 short action receiver which was blueprinted in house. Bolt face is standard .384 bolt face for the .223 cartridge
• Shilen 6mm barrel blank with a 1:8 twist and a #5 contour. Finished at a length of 26″ with an 11 degree muzzle crown.
• Magpul Hunter stock with a MDT .223 AICS compatible magazine
• A Leupold VX-3 4.5-14x40mm scope was selected for this test.

This rifle weighs in at 10.6 ounces with scope.

This rifle was built by Craig’s Outdoor Sports and is for sale. How’s that for a shameless plug!

Test conditions were horrible with gusty winds coming from the left side of the target. Sunshine was nice and bright, just lots of wind. Still the results were more than satisfactory for a starting load in a brand new barrel.

The first step taken in working up a load for the 6mm/.223 cartridge was to consult a loading manual. I chose a mid-range load offering with a Sierra Gameking 85 grain hollow point bullet. 23.5 Grains of H335 powder were used which should give a muzzle velocity of 2500 fps. Unfortunately I wasn’t able to confirm the velocity as I didn’t have a chronograph available at the range.

As stated above, the winds were gusty! 30mph+ gusts were forecasted for this day, and the weatherman was right for a change!

This was the best 5 shot group of the day. The wind was playing havoc on getting a good group. This is at 100 yards. With the gusty winds playing a major factor on group size, this tells me that with more load development and barrel break in that this will make a shooter!

I ran the ballistics through the Hornady ballistics calculator and with a straight 10pmh 90 degree wind you will have 1 moa deflection at 100 yards. With 30+ gusts the string is pretty impressive!

Here is my impression on the 6×45 or 6mm/.223 cartridge. First, it is a very mild recoiling round. It’s a gun you could shoot all day with absolutely no fatigue. What recoil was felt was more straight into the shoulder. Very little to no muzzle flip. Muzzle blast was minimal making this a comfortable rifle to shoot at the range or in the field.

Being as this is a .223 brass parent cartridge it is easy to simple neck up to 6mm by running through a 6mm/.223 resizing die. Just be careful to not mix with regular .223 loads! This is a very efficient and cost effective cartridge to shoot and reload.

Ballistics of the 6mm/.223 or 6×45 cartridge when compared to the 22-250 shows that with an 85gr bullet the 6×45 will out perform the 22-250 from 300 to 600 yards due to the heavier bullet and better ballistic coefficients.

Overall the 6mm/.223 a very fun cartridge. With the mild recoil and better ballistics than a .223 or 22-250 puts this cartridge into a better choice for varmint sized game such as coyotes, ground hogs, etc. It is also a acceptable choice for small to mid sized deer out to 250 yards. Past that and it looses too much kinetic energy to ethically kill deer sized animals.

A rifle chambered in 6×45 would make a much better youth caliber for hunting deer than a .223 that most people purchase for their child’s first deer gun.

The only fly in the ointment to this chambering is the absolute lack of factory loaded ammuntion. To shoot this caliber rifle the shooter will have to roll their own ammo. But that increases the fun!

DISCLAIMER: For reloading information: WARNING: Reloading can be dangerous if you have not been properly schooled in how to reload ammuntion. The loads shown are for informational purposes only.  They are only safe in the rifle shown and may not be safe in yours. Dangerous chamber pressures can occur resulting in serious injury, damage to rifle, or even death if proper reloading steps are not followed.  Consult appropriate load manuals prior to developing your own handloads.  Craigsoutdoorsports.com and its authors, do not assume any responsibility, directly or indirectly for the safety of the readers attempting to follow any instructions or perform any of the tasks shown, or the use or misuse of any information contained herein, on this website.