Home Forums Hunting & Shooting Custom Rifles & Wildcats 7mm-300 Win Mag Cat

FVA: The Weatherby is a good case as well,but it may be worth thinking through that the Weatherby and Remington are so close in capacity that they are really the same thing....and the Weaterby does what it does due to higher presures and the freebore.

I have put together a few 7RM's throated to the 160 Nosler Partition with the base of bullet even with base of neck,and in most barrels(mostly krieger CM and stainless)I have found that loads bore a suspicious resemblance to 7 Weatherby data,so long as I was willing to go to the same Weatherby pressures; the "long throating" of the Remington having about the same effect as Weatherby freebore IME...

But working with the Dakota showed just enough more capacity over the Weatherby and Remington that the case gave more velocity, easily, without hitting a wall.Worth considering....

My riflesmith is chunking 180s out of a 7 Rem Mag at 3,000 to 3,050 burning Retumbo.

I've a keg on order with 600 180 VLD's through Powder Valley.

SU quite a few are using Retumbo for heavies in the 7RM....seems to work,but I have not yet run it...

SU-any idea of how long a tube he's running and how much Retumbo?

Thx

Dober

Mark, I am going to say 26" to 28" tubes. If I remember correctly 70g of Retumbo.

And that's not pushing it hard to get 3k.

My Brux barrel will finish at 27"

For a heavier LR rifle length can be had but if I was using it for a lot of carry I can see going shorter barrel and adding powder capacity via 300 winnie case. I love the design btw.


Travis at http://www.rbrosrifles.com/
He's built a bunch of 7's and has got it down reamer wise for the 180.

Travis shoots and wins tactical comps using a 7 mag and is a WA hunter.
That was a good reason why I went with him for this build.

Another very promising powder for the 7's is N570.

OK, my buddy and I built a total of between 4 and 6 7-300 Win's over a period of about 6 to 8 years. Most of the data was based on 27" barrels. With 160 Nosler Ptns they would deliver 3175-3200. The loads were pretty hot since my buddy used Hagel's method of pressure determination which has since proven to be very hot. The 175's would do 3000-3050. If anyone is getting more it is because of either very high pressure or some newer powders. Jarret has a similar ctg with faster velocities. I bet the pressures are way high. My buddy was a game warden and dedicated hunter. He eventually went to a 270 Win with a 25" bbl.

Rin-we're still playing phone tag, lets try to catch up over the weekend..

I had a 25"/270 barrel on my G33/40 for a while.

Just got in from a nice hike in a downpour slash snow storm looking for yogi. Now I'm looking for a hot shower..

Dober

Dober, both my buddy's 270 and mine are on G33/40's. Got my computer fixed just tonight so I can post again. Have been reading the stuff about 375 H&H AI's and the 375-06 AI and wanting to chime in. Watch out.

I am firmly covinced most guys only need a 270 Win and a 270 Improved (aka Big 7...Rem, Super Mashburn etc.) Won't be long and Bobby will have his Mashburn. Both will mash coyotes way off and I have killed three Eland bulls very dead with a single 130 gr 270. Lets go hunting!

EDIT actually a used a one shot on each of the Eland bulls. I did not kill three with a single shot.

I visited with another buddy who has one of the Gun Werks (Best of the West) LR's in 7 Rem Mag. He is using 70.7 grains of H1000 with the 168 Berger and getting 2980. I think the bbl is either 24 or 25. I am going to try H1000 with 175 Partitions. He thinks the H1000 is more consistent over a wider range of ambient temps than Retumbo.

Sure sounds like a short-necked Mashburn to me

Winchester brass is much tougher than Weatherby brass, and would take more pressure before the primer pockets gave up the ghost.

About 10 years ago I designed and built both 6.5 and 7mm wildcats on a 300WM case. Shoulder moved forward, case taper reduced. The 6.5 was built on a re-chambered Win M-70 Classic 264WM (26" bbl) and the 7mm on a Rem M-700 Sendero (also 26" bbl). The 6.5 duplicated 6.5-300 Weatherby MVs (140 gr. bullet at 3350 fps) and the 7mm was close to the 7mm STW. The suppossed rifle-loony advantage was the cheaper/more available 300WM brass and the std. length action. If you're interested, PM me and I can share the dimensions and reamer source availability.

Good project that met goals but not sure either is practical in today's world - except for an incurable wildcatter loony. There, I've confessed.

Thanks for the offer Wildcatter!!

After RinB and I spoke via PM I've decided that using the 300 Win case necked down with no other changes isn't worth the effort. The gain over the 7mm Rem Mag (I have a fantastic 7 Mag!!) is minimal at best.

At this point I'm looking for a cat that will not require fireforming.

Sounds to me like you have just had a good dose of practicality, or Good Sense, or whatever you wish to call it.

Now Grasshopper, since when does good sense and rifle looney go together?

Never that I can think of...

Dober

They come together real quick when the wife says that since I'm getting a new rifle, she needs a new car.

Or...the grandkids need... it just neva ends

Dober

That 300WM is soon to become a 270 Roy.

The wife doesn't have a need to know, and my daughter is 10 so the grandkids are a ways off.

If I'm not mistaken, ... Rifle Looney and Good Sense are mutually exclusive...

Sorry! didn't mean to confuse anyone....