7mm PRECISION RIFLE CARTRIDGE

[John T]

HOLD ALL ORDERS.

There is a very good chance that The Good Old (ageing) Boy, 7 Remington SAUM, will hang up its boots, probably without a struggle.

It has finally been acknowledged by the industry that a "Rebated" rim is unacceptable. Totally ill conceived. Flattened rims send cases to the bin. 7 PRC has a rim 0.532, a base 0.532.

Case capacity not yet checked, but appears to be just that bit larger to make loading 184's comfortable to 3500 ME.

Likely to put my move to .308 on the back burner.

Regards,
John T.
5.1.23

[Redhawk]

LoL, time will tell, and so will the scoreboard:

[shadow]

Nope, it's to big, the saum might get replaced,
But it won't be by the 7prc

[RDavies]

Nope, it's to big, the saum might get replaced,
But it won't be by the 7prc

Yes the 7 PRC is a little big for much of Australian style E class but the 7mm-6.5PRC version is certainly a viable case for here. Smaller than the straight 7PRC and slightly smaller than the 7 SAUM, a few people here have already chambered rifles for it in Australia. Brass is more available than SAUM and apparently good quality.

[Shobby]

Been shooting a 6.5prc for 2 years in F Open with great results. High BC 6.5m readily available if you plan ahead from Hornady Sierra and Berger.

[Matt P]

To big !!!
Barrel makers and gunsmith will like it though !!!
If availability of SAUM cases ever get sorted, it's the go to IMO.
A 7mm version of the 6.5PRC will also gain traction here, just like it has in the USA. It's a good case with tough brass available. I just don't like the short neck.
Matt P

[Shobby]

I agree Matt would like more length in my 6.5prc neck but happy with its performance.

A few years ago for fun in conjunction with my gunsmith we developed a case based also on the .375 Ruger in both .30cal and 7mm with a 30degree shoulder but a good neck of .411 to comfortably take the longer 230gn 30cals and 197gn Sierra 7mms.
The case takes mid to high 70's powder charge of slow burning powder producing ample speed through the target.

With now availability of better brass I'm now forming these cases from the Lapua 7mm prc brass with less working of the brass compared with the softer .375 brass.
I will not move away from my 6.5prc or my 7mm SAUM to the 7mm prc for I consider no gain. I dont' get any more gain with my case but its fun to shoot.
Based on Hornady's conservative load data the 7mm prc takes approx 14 grains more of the same powder I'm using in my 6.5prc and approx 6 grains of a slightly faster powder for the 7mm SAUM.

[shadow]

I dont see 7mm lapua prc brass on there site and they say they have no intention of making it in the future

[Shobby]

Sorry Shadow 300 prc which I can form them to my case with no trimming until checking after first firing.

[shadow]

All good mate,

[John Weigel]

Matt is right, the newfangled 7/6.5 PRC has a shorter-than-Saum neck.I hadn't realised that. It seems to be a Murphy law that cartridge designers never give enough neck, just as sizing dies are rarely short enough to avoid contact with shellholder just as desired bump is almost achieved. Here's a comparison of four 7mm F Class candidates relating to this thread:

7 SAUM - .311"
6.5 PRC parent case for expanded neck wildcat - .272"
7 WSM .243"
284 Winchester .295"

[Matt P]

Matt is right, the newfangled 7/6.5 PRC has a shorter-than-Saum neck.I hadn't realised that. It seems to be a Murphy law that cartridge designers never give enough neck, just as sizing dies are rarely short enough to avoid contact with shellholder just as desired bump is almost achieved. Here's a comparison of four 7mm F Class candidates relating to this thread:

7 SAUM - .311"
6.5 PRC parent case for expanded neck wildcat - .272"
7 WSM .243"
284 Winchester .295"

Yep and then when you neck up the 6.5PRC you lose a bit more neck !!

[PeteFox]

So is the way to solve this to resize 7mm PRC brass down to 7/6.5 PRC and trim to length?

This is some 270W resized to .308W that I experimented with years ago.
Pete

Screenshot_20230107_110121_Photos.jpg

[John Weigel]

Hmmm, this is beginning to look like yet another expensive rabbit hole...

[John T]

All of you are absolutely correct; FAR TOO BIG.

Amongst the articles I read there was this; THE 7 PRC IS DESIGNED TO SHOOT 180 GRAIN BULLETS AT 2950 FPS.

That discombobulated me.

180's at 2950mv, 3480me, is about as close to Everest as you will get with a 7mm.

Turns out that the 7 PRC is not the brother of the 6.5 PRC. It has an entirely different design.

Tracey bowled Hornady 0 (1). Got 'im. Yes!

Steve Hornady is a marketing genius. He can re-image a product like no one else. About 20 years ago he challenged the 300 WSM and the 300 RSAUM with his 300 Ruger Compact Magnum, but no case manufacturer would run with it. Was it the name, "Ruger"?

The 6.5 PRC parent is the 300 RCM. Lapua and Norma love the 6.5 PRC, as do American shooters. What's in a name?

"Load From A Disk" spec sheet for the 300 RCM tells me that the engine room/powder chamber wall is 0.0225 at the Web and 0.0112 at the Shoulder. Thicknesses for the 7 SAUM are 0.0404 and 0.0202. Based on that information, the capacity of the powder chamber of the 6.5 PRC is larger than that of the 7 SAUM by more than 5%.

Shobby, John, Frank and anyone who has loaded the 6.5 PRC and the 7 SAUM, what do you say?

IF LFAD and my calculations are correct, Shobby, you and your gunny could make a very nice 7mm, with at least 3% more powder chamber capacity than the SAUM and with a 0.315 neck.

Regards,
John T.
9.1.23