Reloading the new 7mm Backcountry.

[45-90]

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.

 

[45-90]

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.

 

[45-90]

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.

 

[45-90]

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.

 

[45-90]

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.

 

[Graywolf.260]

Thanks for the impressive report. Seems like this is destined to take off once the commercial reloading components are available. What rifle did you get?

 

[45-90]

The Weatherby 307 Alpine CT.

 

[4O6shootist]

Please neck this down to 6.5mm and see what it'll do with 156 Bergers!

You should mass produce your dies, bushing style, so people can wildcat the alloy case please!

 

[45-90]

Please neck this down to 6.5mm and see what it'll do with 156 Bergers!

I already shoot 6.5 CM in hybrid cases
140s to 3150 fps, but run the 150gr SMK near 3000 fps and the 153 hr Atips 2960 are two good load.

This 7mm BC case in steel necked to 6.5 and 80,000 psi ...would be really fast.

The 7mm BC in brass cases was only 50 fps behind the 7 PRC when both had 20" barrels firing factory 175 grs PRC vs my 175 gr fireforming brass hand loads.

But the 7 PRC is 250 to 300 fps behind with steel cases and both with 20" barrels...both firing factory loads.

 

[45-90]

Made another 100 pcs of 7mm BC brass cases tonight in about an hour....have 200 more to go.

Take 280 Ackley imp brass. Got 300 for 65 cents ea. Free shipping.

No case lube needed...just changing the 40° Ackley shoulder to 30° and moving it back slightly.

Run through a 308 body die bump the shoulder back at partially at 20°

Then run through your home built 7mm BC FL die ...no lube necessary.

Trim to length on the lathe or mill, and deburr.
May use mandrel here before seating the bullets.

Here's what the steps look like...and in an hour you have a hundred pcs of 7mm BC brass.
Use 280 Ackley Imp load data to fireform.

When changing to steel cases I lube with Lee Resizing Lube, set the die .003" down farther toward the shell holder.

Pump the press handle several times to help size the steel cases as you bottom out the press handle.

It's not hard just a little different, to get used to.
Plus the die slightly oversizes the steel in order to also size the brass sufficiently.

The die making takes a little experimentation between the two metals used with this cartridge...

 

[45-90]

Please neck this down to 6.5mm and see what it'll do with 156 Bergers!

You should mass produce your dies, bushing style, so people can wildcat the alloy case please!

The steel case 7mm BC necked down to 6.5 would have only a little less capacity than the 6.5 Weatherby RPM running at 64000 psi...but 80,000 psi with slighty less capacity would add 200 fps to 300 fps extra depending on the bullet for the same barrel length.

I only do this as a hobby.
If I were younger and there was a large enough demand then ya might start a business...but that's hard to do in today's over regulated states.

I'm a retired machinist, oldschool and CNC, working on refuling nuclear reactors, weapons grade, and electricity, aroespace, to robotics.
I have my own basic machine tools, so that's why all the experimentation is going on.

Want it done, want it made,... do it yourself.
Old-school.
Don't mind showing and having others learn or adopt and adapt what I do to suit their needs, but some of this stuff requires machining experience.
Too old to hold apprenticeship classes, or start a business.

But all these companies bringing out new cartridges, then it's where are the rifles, where is the ammo, where are the cases, and reloading dies, bullets, powder, or reloading data.
Slow to bring support for these cartridges, and they wonder why people lose interest.

When you can do it yourself ya don't have to wait.
Build that custom rifle in a day, after you've accumulated your ordered parts.

Or make brass cases from common calibers. Cut down solid heads and recut extractor grooves.

Plus.. got an idea ...implement it!
I can build a 6.5 -7mm BC if I so desire.
I can go out in the shop and form a case in little time.
That would be a real hotrod, by the way.

I encourage people to look into maching classes at junior colleges...and start learning.
But around here, they have sadly eliminated those classes.

 

[INgunner54]

The steel case 7mm BC necked down to 6.5 would have only a little less capacity than the 6.5 Weatherby RPM running at 64000 psi...but 80,000 psi with slighty less capacity would add 200 fps to 300 fps extra depending on the bullet for the same barrel length.

I only do this as a hobby.
If I were younger and there was a large enough demand then ya might start a business...but that's hard to do in today's over regulated states.

I'm a retired machinist, oldschool and CNC, working on refuling nuclear reactors, weapons grade, and electricity, aroespace, to robotics.
I have my own basic machine tools, so that's why all the experimentation is going on.

Want it done, want it made,... do it yourself.
Old-school.
Don't mind showing and having others learn or adopt and adapt what I do to suit their needs, but some of this stuff requires machining experience.
Too old to hold apprenticeship classes, or start a business.

But all these companies bringing out new cartridges, then it's where are the rifles, where is the ammo, where are the cases, and reloading dies, bullets, powder, or reloading data.
Slow to bring support for these cartridges, and they wonder why people lose interest.

When you can do it yourself ya don't have to wait.
Build that custom rifle in a day, after you've accumulated your ordered parts.

Or make brass cases from common calibers. Cut down solid heads and recut extractor grooves.

Plus.. got an idea ...implement it!
I can build a 6.5 -7mm BC if I so desire.
I can go out in the shop and form a case in little time.
That would be a real hotrod, by the way.

I encourage people to look into maching classes at junior colleges...and start learning.
But around here, they have sadly eliminated those classes.

This is awesome!! I would love to come hang out, and sweep your floors for a week or so and just shoot the shit to soak up some knowledge! This kind of thing fascinates me, and hats off to you for putting it out there! Thank you!

 

[Mulepackhunter]

Very nice work, I jumped into the 7mm Backcountry but havnt had much work out of it. Im putting parts together now to do a shot out barrel build. Cutting middle out of a shot out 7mm barrel and building a 16 in mountain rifle suppressed. We will see how that barrel shoots. I have several laying around so why not. Awsome data.

 

[45-90]

Very nice work, I jumped into the 7mm Backcountry but havnt had much work out of it. Im putting parts together now to do a shot out barrel build. Cutting middle out of a shot out 7mm barrel and building a 16 in mountain rifle suppressed. We will see how that barrel shoots. I have several laying around so why not. Awsome data.

Is the shot out barrel an 8 twist?
I found the 197 gr SMK requires a 7.5 twist.
The 8 twist has been accurate with most bullets it tried ...except the 197 gr SMK so far... so check your barrel twist rate to the heavy for caliber choices available in 7mm BC factory loads...those factory loads are pretty zippy even in a 16" ....the Federal factory 170 gr gr Terminal Accent was going 3100 fps in my 20" with good accuracy, and low SDs.
Check with bullet stability calculator to see if it fits your twist.
Have fun with your7 mm BC project.

 

[Mulepackhunter]

Ya these barrels are 1:7 and i have a few Berger 175 elite hunters
I think its funny that you made your own dies and rcbs hasnt yet. I was told at Shot Show by the federal engineers they were on board and in process. Damn salesmen got me. I think this thing has one spot to fill and thats a really short hunting gun suppressed. I cant find anyone who wants to build one so I guess ill build my own. I also have a case of the 170 Terminal factory ammo to start with.

 

[4O6shootist]

I'd be very selective on your can choice for a 16in 7BC. Muzzle psi will be very high inside the supressor.

 

[45-90]

Reloaded the steel cases 3 times and fired them.
And fireforming brass cases today...will have 350 brass cases when done for reloading.

Was able to reach 2801 fps with Mag Pro brass cases and 184 gr Berger in a 20" 7mm BC.
And 2833 fps with Brass cases and 180 gr ELDM.
Steel cases went 3000 fps with 184gr and MagPro in the 20" barrel.
The barrel likes 180 gr factory 2nds 14 rds fired without letting the barrel cool...it was very hot.
Ladder test 184 bergers 2 powders steel and brass cases.
184 gr Berger with 67 gr of Mag Pro steel cases 3000 fps last group of the day .649" 3rd reloading of steel cases...OK group for a hunting rifle but this one needs a little tweaking. Same for the 180 gr ELD-M they need a little tweaking. This barrel really likes 180 gr non tipped match bullets.