Home Forums Hunting & Shooting Custom Rifles & Wildcats The 7mm Mizzum

This thread has me lusting after another big 7mm. A 7 Ultra on a model 70 is appealing and it would fill the niche between my 300 ultra and 280,270 and 25-06......

B: Get one!

Bob:

Thanks for the info on the 7 MM. That clears it up.

Very cool, Bob!

Gonna rock a Big 7 one of these days. I kind of wisht I'd listened to you and Dober and done my Sendero as a 7mm, but if memory serves they only offered it in the 7 RUM at the time which just REEKS of "overbore"......

Thanks Jeff!Well you could get a PacNor or something for your 300 and rebarrel....like falling off a log!That would be very simple.

That 7RUM is quite a cartridge,fastest of the bunch, but will likely chew up barrels pretty quick....but it works!

123: You're welcome!

Seems to me that PN has a Mashburn reamer...

Dober

There ya go,Jeff!

Bob, I checked with reception - the "ugly" M70 in 7mm hasn't arrived yet. WTH?

Scott you are relentless.....

It has assigned tasks for November......I am teetering with dolling it up, but may leave it ugly just to annoy people

You're going to annoy me if you douse that thing with polane.

Yeah, that's the plan. As you know it won't break my heart to consign the tube on it now to the scrap heap of history (though it is accurate).

The 7's are interesting. The difference between what my loading books say, and what people claim, is pretty dramatic for say the 7mm Mag. From there, there the fire-breathers like the STW and the RUM. I guess what you are saying is that the mizzum fits nicely in between.

I can't like a forming step with the brass though. I essentially have to do that with my 300 WM and annoys the hell out me.

The fire forming load I use is so accurate that I can find a ton of uses to form with it. I'd sure not worry about it but that's just me.

As for the diffs in speeds of the big 7's I'd find a couple people with tons of experience with them and go with what they say.

Dober

Jeff the form load is fun....doesn't kick at all and is accurate as Dober says.Forming brass is pretty cool too!It really is an easy cartridge to work with; no surprises, gets the advertised velocity and does not kick bad at all......

veddy nice all round!

What is wrong with the 300 barrel?

I don't like wasting components. It adds a box of primers, 50 bullets, and 1/3 lb of powder to the cost of 50 pieces of new brass!

Getting to know a new rifle, not so bad, but as an ongoing thing it annoys me with my rifle anyway.

(mine has a very sloppy chamber, won't shoot well with virgin brass, to top it off I only get ~4 maybe 5 loadings before the necks split out so to even get THAT, I have to anneal, then form, THEN finally have usable brass.)

Geez......that sucks!If not a rebarrel, does it make any sense to set the barrel back a few threads and rechamber with a good reamer?

You could also set up the throat for your favorite bullets and things would get rosy real quick

Bob:

The Speer manual I mentioned in my first post has several loads listed for the 7 MM Mashburn, with different weight bullets.

The book was publishd in 1960, so I don't know how up-to-date the data is, but if you want, I can send some of the loads, if you don't already have them.

123: Thanks that would be great!

I enjoy comparing the old powders to the newer ones' and how they all performed.

For now, I am pretty well set for loads,and it has boiled down to:
160 Partition-75 H1000-3150 fps
175 partition- 73 H1000-3050
160 Bitterroot-74-H1000 for the sam vels as the 160 partition.
139 Hornady-65-IMR4350. This is Dober's fireform load and gives 3150-3190 from my barrel.

I also worked up a "form load"using large pistol primers, Bullseye,and RCBS corn husk tumbling media. This works great as well.

What is interesting is that Warren Page's load for the 175 was 73 of the WW II H4831 and the 175 partition at 3050;same velocity and same charge weight I got with H1000.

Bump for a good round and the people who like it.

I couldn't sleep, so I've been up reading about the 7-MM MSM

I'm getting ready to do another build. Might as well have a 7-MSM


Did Bob ever get that deer in Wyoming?

You all have a good day

I can really appreciate the Mashburn.

But, I am so enamored with the 280 AI that I will likely never move past it.

Still, hats off to those who are unwilling to rest with the mainstream stuff.