Home Forums Hunting & Shooting Long Range Hunting 7mm Wby and LRAB results...........

Not yet, I'm hoping to get it out for distance on paper soon to really see what these bullets will do.
From what I have read, Nosler's BC hold true. I've never known them not to.

SU35
Nice groups!

Now you having me thinking that instead of a planned 300 WBY project this winter I will re-barreling a 257 Vanguard to 7mm WBY, a few flutes and the extra Back Country stock I have sitting in the safe would make a sweet faux 7mm WBY Back Country.

Funny my first experience on how good the 7mm Weatherby�s shot started nearly 40 years ago when a good friend got a 7mm WBY in a deal that the Bank of Denver was running, (I think it was Denver) you put up $2500 into one of their CD�s and got a Mark V instead of interest!

Anyone else old enough to remeber that bank?

Gentlemen,

Several years ago a friend dropped off a 7mm Weatherby. About that time I purchased a Corbin press to make bullets. I worked up the best load I could with Nosler Solid Base 150s. It was a factory rifle with no mods, not even a trigger job. It would routinely put five into an inch at 100 yards. What was a real surprise is it would put five of my 140's into half that.

By the way it really liked the original Barnes "X" bullets.

Oh, yeah, I remember that bank.

Bob,

If you'd looked up pressure-tested 7mm Weatherby data from present sources, you would have found the velocities you were looking for. In fact Nosler lists two 160-grain loads from a 24" barrel that are essentially 3200 fps.

I know the 7mm Mashburn will fit in a standard magazine, but unless the chamber has some freebore it won't match 7mm Weatherby velocities. It only holds maybe 4-6 grains more powder than the 7mm Remington Magnum, depending on the brass ad bullet, which ain't enough to get a 175 to 3050 from 22" barrel unless there's some firewalling or freebore involved.

I just built a 7mm mashburn and had the throat cut to 3.53 inches. I found that I was getting more velocity variation than I wanted and also not quite getting the velocity that some of you are getting with that round. I dropped the gun off at the smiths and am having him cut the throat out a bit longer. I believe that I told him to cut it so that the base of a 160 grain accubond will be seated flush with the base of the neck. I believe that the round when seated this way will just fit in the magazine and have an overall length of 3.67.

The gun should still shoot well with the extra throating, correct? If push comes to shove I can just load up one of the longer 175 grain accubonds to minimize jump to the rifling.

Can the 'smith make sure the throat is only a half thousandth over bullet diameter?

I would really like to see pressure data on a 7 RM std throat, a 7 RM with a throat matching a 7 Wby, then the bbl cut for a 7 Wby body, then cut to a Mashburn. I am guessing that a 7 RM with an optimized throat will do everything that needs doing.

Anyone want to chip in? I will send some bucks to JB for a barrel. Should be able to get it all done with the same tube. Use a Savage nut set-up for headspacing the barrel. Who is in? Need someone to cut the various chambers. Maybe Melvin or Echols or ?

I believe JB's formula for gain in velocity being a function of capacity and can't see the difference.

Mathman,
The question is, does the reamer have the correct dimensions. Has nothing to do with "the smith" and everything to do with the reamer dimensions.

Really? No shiit?

I know, I know, I've nitpicked semantics too.

Just checked Nosler online:
7 RM 150 grain 3.290 OAL has 78.0 capacity
7 Wby 150 grain 3.369 OAL has 81.4 capacity
So with the same throats and same OAL and same pressures there should not be much difference, right?

Always a good idea to eliminate all variables.

Mathman,
Not trying to harass you; just being precise, nothing more.

Guys: I just heard from another knowledgeable forum member who built one and has shot it....he seemed pretty happy with it and noted how the case swallowed large amounts of powder and delivered excellent velocities so far, but he has only worked with one bullet and powder...RL25 and 150 gr BT's. He has also had and is familiar with the 7mm Weatherby and 7 Rem Mag.

His words(he called me this morning)....the Mashburn is a big, easy going 7mm magnum case that so far delivers the velocity very easily.....I'm paraphrasing.He will post his results later.

79pa if you are having a problem getting the velocity I don't know what to tell you....you are the first out of maybe 12-15 people who have built one having that problem that I have heard from....I am losing count fast...

I know for a fact that you can long throat a 7 Rem mag till the cows come home and it will not deliver Mashburn velocities.

I did not build this rifle to keep everyone happy, convince anyone else that they should have one, or proclaim it the "best" 7mm Magnum on earth.

Nor did I build it to debate its merits with a bunch of people who don't have one and want to speculate on what it will do. I only post results I have received and what people who report back tell me.If that does not make you all happy, I don't know what to tell you .

I built it to make me happy and it has delivered exactly what guys like Page and Hagel said it would.Matter of fact...it is so "spot on",it's almost spooky.

No offense taken at all. You said what I meant. You caught me being sloppy, fair and square. My response to you was in jest.

You dont have to justify anything to anyone. but it seems like you are always reassuring yourself about the mashburn. The wby and mash do the same things. Not many guys like the weatherbys, no big deal to those of us that own them..We report what they are capable of but some dont want to hear it i guess.

Its kinda interesting that you say the mash has to outrun the weatherby cuz its bigger (i'm sure it can by a little)then you say that the STW doesnt gain anything over the mash?

How how difference is a 7mm Wby loaded with 160 grain bullets versus a 7mm Wby with a 175 grain! Obviously the 175 bullet means more recoil on your shoulder. But what about on Moose, Elk, Bears? Any difference in terminal performance?

When I discovered there was something other than thirty caliber I purchased a Klienguenther K14 7 Rem Mag with a 26" heavy barrel. After awhile I had a Douglas Premium Airgauge 28" heavy barrel installed. It was chambered for .300 Weatherby necked to 7mm. It sent the Nosler 160 at 3,360 feet per second and the 175 at 3,150 feet per second. It was my mountain and forest rifle.

Had the chance to bust a few more caps today, at 300 yds.

With a 100 yd sight in, my first shot hit 6" low at 300.
Shot into a stiff crosswind then gust came up hard I quit till another day. This gives me an idea of where I'm heading.

Looks encouraging at 1.4".....BC's look good, even better.

I clicked two moa on the dial, you can see the results.
This is what JBM says for a 100 yd zero for my dope.
300yds -8.8 drop -2.8 moa (My drop was 6" and I came up 2 MOA).....

Rick,

I am sure a gunsmith I know with a Pressure Trace system would do the chambering, testing, etc. for the right price, but what would be the point?

Here's a list of the 7mm magnums that have had plenty of load development done with electronic testing equipment: 7mm SAUM, 7mm WSM, 7mm Remington Magnum, 7mm Weatherby Magnum, 7mm STW and 7mm RUM. We know what they will do at pressures of 62-65,000 psi, with the SAAMI chamber/throat dimensions.

I don't know of anybody who's done the same testing with the 7mm Mashburn, partly because there is no standard chamber/throat for the 7mm Mashburn.

It's also established that guessing pressures without some sort of sophisticated equipment is impossible. This is exactly why the 7mm STW went from being a wildcat "safely" capable of pushing 140-grain bullets to 3600+ fps to a factory cartridge with 140's at 3350-3400. The "safe" wildcat handloads were pressure-tested and found to be 70,000 psi or even higher. This is because the traditional "pressure signs" don't usually show up until 70,000+ psi.

What we know about the Mashburn is that it gets X velocity in the rifles of some handloaders. We don't know what the pressures are, but do we do know the handloaders who get those velocities use traditional pressure signs to judge whether their loads are safe.

Like Bob, I don't really care about all this as long as he's happy with his 7mm Mashburn. But I also believe it would have been a lot easier to get to the same place, at known pressures, with a 7mm Weatherby or 7mm STW, depending on how long a magazine's desired.