Reloading the new 7mm Backcountry.

45-90

Major Hide Member
Full Member
Minuteman
May 29, 2023
2,239
2,210
USA
Monday I purchased a new 7mm Backcountry rifle to see what it was all about.
I already load the hybrid cases, but this new steel case seemed interesting.

Shot the 7 BC on Tuesday, and was pleasantly surprised at the velocity.

Wednesday built dies and reloading support accessories.

Thursday loaded up some fired steel cases.

Shot them today ...
All I had for 7mm bullets were the 180 gr Berger from the old 7mm Mag days, when I quit 7mm cailber.
Top velocity was 3118 fps for the 180 gr Berger in a 20" barrel in a 6 lb carbon fiber rifle.
180 gr Berger.
The place to run it is at 3050 to 3075 in my rifle, around 64.0 grs of RL 26.
65.5 is max at 3118 fps. Noticed one had a little more resistance on bolt lift in the 3100 plus fps area, so I stopped the RL 26 testing there. But at 3050 fps it's an excellent load...no issues easy extraction not extra effort in bolt lift...accuracy was there also with two touching.

RL 25 67.0 grs = 3030 fps, no issues.

Mag Pro 68.0 gr = 2975 fps a powder that's easily available. No issues. Shoots good.

Unfortunately you have to have quite a bit of machining experience to make the dies and support tools necessary.

RCBS should have dies on the shelf.
I had only a little trouble with steel neck tension and had to re-do the die. All done in a few hrs. Its a learning curve even though I do many hybrid cases and lots of case forming.
Ya don't need carbide dies...and these cases can be loaded rather easily.
It's just a little different.

I find this new Federal BC cartridge to be a real breakthrough...especially for short barrels and hunters who want 6 lb rifles with performance in a short light package.

Probably not interesting for a target shooter.

I will also be running brass cases in it for moderate use as soon as I form them.

You'll never run out of brass cases 270. 30-06, 280, can all be formed to 7 mm BC.
Expect lower velocities of course.

RCBS should not be having trouble making dies ...I only have 35 yrs as a machinist...anf they've been making dies a lot longer than that.

This is really a good hunting caliber...it needs more industry support.
And you can reload it with existing powders, some of which are hard to get but I went for one that's available and cheaper and still get good velocities with the 180 gr Berger.
 

Attachments

  • 20250905_130526.jpg
    20250905_130526.jpg
    1.6 MB · Views: 58
  • 20250904_184301.jpg
    20250904_184301.jpg
    810.6 KB · Views: 59
  • 20250904_123346.jpg
    20250904_123346.jpg
    1 MB · Views: 58
  • 20250903_204419.jpg
    20250903_204419.jpg
    1.2 MB · Views: 50
  • 20250903_205146.jpg
    20250903_205146.jpg
    1 MB · Views: 50
  • 20250903_205155.jpg
    20250903_205155.jpg
    1.3 MB · Views: 49
  • 20250905_132806.jpg
    20250905_132806.jpg
    1.2 MB · Views: 50
  • 20250905_133120.jpg
    20250905_133120.jpg
    1.6 MB · Views: 53
Making a fair amount of brass cases for the 7mm BC.
Made another die for this project and it turned out well.
So this way I can load lower velocity brass cases for lighter loads and steel cases for magnum loads. Making it even more versatile, like a 38 special and a 357 mag combo.
 

Attachments

  • 20250909_002150.jpg
    20250909_002150.jpg
    1.2 MB · Views: 31
Subsonic loads work in the 7mm BC.
The 180 gr hp match were stabilized at 930 fps.
Fun to shoot.
Just incase ya want to shoot subs in your 7mm BC.
 

Attachments

  • 20250915_142958.jpg
    20250915_142958.jpg
    889.3 KB · Views: 14
  • 20250915_142226.jpg
    20250915_142226.jpg
    1.3 MB · Views: 14
Made up a bunch of brass cases for 7mm BC and shot them with various bullets and powders.
This barrel loves 180 gr 7mm match bullets.
Fireforming cases the smallest 3 shot group was .060" with factory 2nds and reformed 280 Ackley Hornady brass cases.
Average velocity is around 2700 fps.
Remember these are fireforming brass cases with factory 2nds.
The 175 gr tipped bullet was stringing vertical but the barrel was not allowed to cool, and was very hot at the end of a 25 rds string.
Load data on the paper cards.
 

Attachments

  • 20250915_153140.jpg
    20250915_153140.jpg
    1.5 MB · Views: 10
  • 20250915_155520.jpg
    20250915_155520.jpg
    1.4 MB · Views: 8
  • 20250915_214248.jpg
    20250915_214248.jpg
    877 KB · Views: 9
  • 20250915_214822.jpg
    20250915_214822.jpg
    969.1 KB · Views: 7
  • 20250915_214106.jpg
    20250915_214106.jpg
    1.3 MB · Views: 9
  • 20250915_214059.jpg
    20250915_214059.jpg
    1.1 MB · Views: 8
  • 20250915_214055.jpg
    20250915_214055.jpg
    1 MB · Views: 9
  • 20250915_171016.jpg
    20250915_171016.jpg
    775.2 KB · Views: 8
Last for the 7mm BC 20" barrel, was a light bullet load, the 120 gr Barnes TTSX BT

Fireforming "Brass" cases.
59.2 gr Hybrid V100. = 3223 fps
59.9 gr Hybrid V100. = 3277 fps
60.1 gr RL 17 = 3381 fps

"Steel" 7 mm BC case
63.9 gr RL 17 = 3615 fps.

Do NOT get your powder charges mixed up between brass and steel cases.
Brass cases can Not handle 80,000 psi.
This is using brass as a more moderate load option ...very similar to the 280 Ackley Improved in a 20" barrel.

197 gr factory 2nds reached 2940 fps in steel cases, but were not accurate...they require a 7.5 twist I have an 8 twist.
They didn't seem to go sideways but accuracy was not there.

The 180 grs is where the accuracy is with this barrel running Steel Cases over 3000 fps to 3100 fps with different powders.

So the 7mm BC is very versatile and plenty accurate for a hunting cartridge.
Shown here with subsonic, 280 ackley, and high pressure high performance loads...lots of choices.
 

Attachments

  • 20250915_145042.jpg
    20250915_145042.jpg
    1.3 MB · Views: 9
  • 20250915_160701.jpg
    20250915_160701.jpg
    1.3 MB · Views: 8
  • Like
Reactions: Graywolf.260