My love of all things .284 (and an incoming magnum length M-70 stainless) is fueling the desire to experiment.

Anyone have experience with this round? Will it duplicate the 7mm Weatherby?

I'm looking at a 24" Pacnor.

Yes, I realize it will not do anything about half a dozen other rifles currently in the safe will not do, but being a loon needs no justification.

I had Pac Nor build a couple of 7 STW's. I get far above what the reloading books have in them for velocity, and accuracy is where the shots touch at 100 yards...you may want to consider the 7 STW.

I had a 30-338 built a few years ago. It offered nothing over a 300 win mag. but it was a cartiridge i thought I needed to try

I think there is a little "loon" in all of us

+1

Sounds like the 7mm Mashburn. Dober has been running one for a long time, you might check some of his posts.

I have a 7/300WM and it will run a 140 grain bullet at 3350 top end out of a 26" Krieger. Probably high 3200 with 24".

The 7/338RUM on the other hand will deliver the same bullet at 3650.

I too suffer from 284flu.

338, considered the .338, but case mirrors the 7 Rem Mag, shoulder on the .300 sits forward, gaining roughly 10 grains powder.

Tim, that's what I'm looking for, thanks.

Action is currently a 7mag/300WM/338WM action, therefore the STW is not on the list, nor is the Mashburn. (Yet .....I'm sure I'll get to them eventually.)

The STW can be on the list for a Win M70.

All you would have to change is the mag box, follower, ejector and bolt stop/release. Wala, instant 3.6" cartridge loading capability. And not too much money invested in parts.

If I wanted an M-70 in the STW, wouldn't it just be easier to buy an M-70 in STW?

Don't want an STW.

Hoping to duplicate 7mm Weatherby ballistics in a wildcat of interest, therefore need input on the 7mm-300 Winchester.

Curious Doug but why is the Mashburn not on the list yet the 7/300 win is?

And yeah as mentioned and as you probably know I do have a fair bit of experience with the round. My 3rd barrel is about dead...grin

Not many rounds have the Panache of 7 Mashburn Super, 4 whatever that's worth...

Dober

Hell Mark, you've got one, Bob has one in the works, everybody and their brother runs the Mashburn these days, it's too common!!!

(Plus I've got a whole pile of .300 WM brass)

Model perfecto, that's what we use to form the Mashburn brass, plus I have pages of load data I can grace you with...grin

Dober

The 338RUM is not quite the same squirrel as the 338 Win. Slow down a bit.

No where in my posts did I say it was.....

OK Mark, convince me.......

24" bbl......

150 and 160 gr. velocities?

Ok, I guess you`re right. Sorry.

Pardon me for pointing this out.... But according to my Handloaders Manual of Cartridge Conversion , the 7mm Mashubrn Super IS a .300 Win Mag necked to 7mm. Case length = Same/same, Shoulder angle is same/same.

I mean, the only difference is the nomenclature... I don't understand what all the fuss is about...

Seems to me that a lot of pointless rhetoric could be avoided if each budding wildcatter would just spend the $25 for the book. (Besides that, there is alot of useful information in it.)

No offense meant to any previous poster on this thread...

GH

No worries Tim, a 7mm/338 RUM = 7mm RUM, no? 26" bbl, STW/RUM length action. I have two .300 Weatherby's, one may become a 7mm-300 Wby down the road.

None taken Grasshopper, tat's the sort of info I'm looking for. I was under the (mistaken?) impression that there was fireforming involved with the Mashburn.

Seemed simpler to just neck down the .300 brass with no other changes.

I do need the Wildcat Cartridges book from Wolfe though.....

no is correct. I will leave you in gracious hands.

Doug...many a night,while in somewhat of an intoxicated stupor,I have run 300 Win Mag brass through a 7RM neck sizer and contemplated the creation.....I would call RinB(on here),and he tells me he had reamers made.

I think a buddy of his affectionately known as "Maximum Moe" from Washington State, has had one or two.....

It is, by all counts,the Mashburn, which may very well be the "Perfect 10" among belted 7 mags...so good,in fact that Dober has seduced me to spend ridiculous amounts of money to have one...

Please build a Mahburn; I want to get together a coven of Mashburn people and have someone make us headstamped, factory brass....the manufacturers may not know what's good for us.....but we do......

But if you decide to do a 7mm/300Win. please do it on a H&H OAL;I come down with the hives thinking about jamming thsoe bullets way down in the case and squeezing them into a 30/06 action.....

I need a drink now....

Must resist......the dark side..........

Resistance is futile......

Bob, what would I need to do to 300 Win Mag brass for the Mashburn?

My thought process is that the 7mm Rem Mag & the 300 Win Mag perform wonderfully in a 24" bbl, hence the 7mm-300 WM should as well.

The STW, the H&H necked down, or the 7mm-300 Wby would necessitate a 26" tube...

Doug: The Dobermeister knows best....the way I get it,form dies from Redding are needed,specifying 300 Win mag brass.Mine are ordered,16 weeks out.....Run the 300 Win Mag brass up through.Then you gotta blow the shoulder out slightly; the case has somewhat less taper than....uh...I dunno;300 Win Mag.

Dober uses a load with 139 Hornady. I'm gonna try a Cream of Wheat recipe with tissue and parge pistol primer to get cases through forming.

NYR,

I just looked in the Wildcat Cartridges book by Wolfe Publishing... There is a treatise on the 7mm Mashburn Super by Bob Hagel. (figured there was...)

I've always laboured under the impression that there is always some fireforming involved whenever one changes any dimension on a case. I've always accomplished this by using up partial cans of powder and partial boxes of bullets that I have no desire to hunt with. (And I have alot of both...)

I make no apologies for being an inverate and anal handloader. And am under the opinion that trigger time at the range is NEVER a waste of time. If fact, a leisurely day shooting with one or two of my buddies rates rather high on my list of enjoyable activities. (Not far down on my list is discussing the intricaties of rifle cartridges and handloading for them.)

As always: Others mileage may vary...

GH

BTW: a 7mm/.338 RUM is NOT the same as a 7mm RUM. The 7mm RUM uses a 2.85" case and the .338 RUM uses a 2.76". Why Remington used a different case length for the .338 is beyond me...

Grasshopper is of course right...this is a frivolous exercise.But the Mashburn pre-dates the 300 WM,is nostalgic,uncommon today...that means it must be done.

To paraphrase the writings of the Apostle Paul: Almost thou persuadest me to build a 7mm Mashburn...

Grasshopper,

Dober sent me a copy of that Hagel article a while back, good read.

Trigger time is always time well spent!

Bob,,

The Mashburn is a fine round, no doubt, but wouldn't the 7mm-300WM just be easier?

Case capacity on the two is just about equal I'm assuming, unless blowing the shoulder out makes that much of a difference?

I'm figuring around 85 grains in the 7mm-300.

The 7mm/300 Win Mag is also called the 7mm Yukon around here...a local 'smith has made a few. A guy I know has one on a custom lefty 700 in a McMillan....I shot it years ago...150gr Ballistic Tips at 3300+ IIRC....

The neck gets kinda short when you reduce the 300 Winny neck to 7mm....but I guess it works...it won't have the bullet seating depth vs mag box length issues of the STW....depending on throating of course...

I just got a 7/300 Win custom from McWhorter Rifles...amazing get one you wont regret it. Mines pushing the 180 VLD 3150 fps

Doug, yes the 300 just necked down would be easier.Butas stated the neck is short,which can limit bullet seating going from light to heavy;........and it has no name

I figure so what...you blow an afternoon or two fireforming the brass....no biggie

dc3483, what are the details on your 7mm-300?

What's the bbl length?

How long of a barrel and what powder and charge if you don't mind? IME you either have a very fast barrel or clock, or your barrel is over 26" and or you're pushing it too hard.

Thx
Dober

Bob,
You seem to have quite a bit experience with the big 7's. Can't help but notice you wrote the Mashburn perhaps being the "Perfect 10" with the qualifier of "among the belted mags".
Throw out the "among the belted mags" and which do you consider the best of the big seven's?
Thanks,
Frank

The gun has a 26" 5.5 contour hart. I'm running 77 gr of retumbo with fed 215 primers. I believe McWhorter is listing these at 3200 fps with viht n570. I didn't try any n570 because I'm gettin well under half inch right now

I've not run any of the Vit powders with any of the 3 Mashburn barrels that I've had nor have I run any Retumbo. If I could get the 180's to perk worth a darn I'd maybe give it a go but I just cant' get them to shoot in this barrel.

Of the 3 barrels I've had (3rd is pretty much toast) I've not found that any of them would go over 3100 in a manner which I care to do with a 175 let alone with the 180.

Could be you've the magic powders and or a very quick barrel or like I said a clock that's a skosh on the fast side. Silly question but have you had good primer pocket life (IE how many times can you load run a 180 @ those speeds and keep the pockets tight?), and have you found that several different lots of powder still hit that speed and feel comfy with it?

Not being accusatory at all, just wanting to know all I can about how you're getting there.

I'm pretty sure that the Mashburn is gonna have a tish bit more speed than the 7x300 Win. It won't be much but I'm thinking it'll be a bit more.

Anyway you cut it, the Mashburn or any of the other big 7's are some kind of wonderful rounds and a pure joy to work with and plane Killing machines @ long range in the hands of the practiced.

The thing I really like is when I pound a lope/deer @ 400 plus that it hits them hard enough that it reminds me of hitting a gopher with a 9 Iron and that's how I like to hit em...grin

Dober

As far as case prep with the Mashburn it's easy. There's a two dies that do the intial forming of the 300 WM case, and with the two dies and a new bag of 50 brass I can do what I need to do in less than 10 minutes including changing out of the dies. You don't need to lube the inside or the outside of the cases for this.

Then, I FL size the cases (which I like to do for most new cases anyway), then charge, seat and fire.

My fire form load for all 3 barrels has been I4350 along with a 139 Horn fb. The load lopes along @ 32 and some change and out of these 3 barrels has been incredibly accurate. I could hunt most all that moves with my FF load and not blink once.

Bottom line, for me the Mashburn is very easy to work with. A long time ago I got to know Hagel a bit and he got me hooked on the round. I'm kind of a sentimental guy (or at least mental...grin) so I flat out love the round!

Aside from nyati there isn't a thing in the world that I wouldn't hunt with it (that I want to hunt) and that says a lot for the round to me. Plus it's very user friendly and I can easily shoot 40-50 rounds a range session with ease and comfort. And a goodly amount of that comes from weirdo positions on the ground and such.

Dober

FVA: I say that sorta tongue in cheek,because all the big 7"s are "good"...mostly I've used the Rem Mag in standard throat and by wildcatting it by using a long magazine box and throating it out some.

But years of using it gave me impressions like any gun nut has,and I always felt it could use a skosh more capacity and a longer neck,the additional capacity meaning not quite getting into the RUM-type case,or requiring a 26" tube,since I prefer 24" barrels on a magnum hunting rifle(a bit handier for all-round use);and I don't want a ton of muzzle blast either....plus I don't care a single whit about "short actions",and have no problem with putting a big 7 in a H&H length box,since that is what we are luggin around when we carry a M70 Classic or 700 Remington anyway.

I've long felt that a 160 gr bullet at an "easy" 3200,and a 175 at over 3000 without leaning too hard and not getting powder charges much over 70-74 gr of powder made up the "perfect" 7 mag.Page's "Old Betsy" chambered for the Mashburn gave 3050 with WW II 4831 and a 175 gr bullet from a 22" barrel;with today's better slow powders I would not be surprised to see a 175 gr bullet at 3100 from a 24" tube.

So, for me,in a belted case I always thought(guessed,imagined, interpolated ) that the Mashburn would be about picture perfect. I just never got around to doing it before,mostly because I am not really a wildcat fan,but I figure what the hell....mights well go for it.

In a non belted case, to my mind the 7mmDakota is about "perfect".Only drawback is cost and availability of brass. I can make Mashburn stuff from commonly available 300 Win Mag brass.

If Ruger/Hornady would stop trying to jam the short action mania down our throats,and neck down the 375 Ruger to 7mm and 30 caliber(giving us available brass from the factory) I would be a happy camper and would look no further for a big 7mm.

On the present subject the 7mm on a necked down 300WM case is not new,as Bob Hagel had correspondence with a fella from Argentina that was doing it quite a ways back,and wrote about it;like most wildcats, if you dream it up,likely some one has been there before....

Bob,
You and Mark keep it up and theres gonna be another 7 Mashburn in WV. What twist are you going with? Shooting one with a 139 has got to be more comfy than shooting a 300 Win w/150?? Wonder of the difference is noticable?
I have a new High Tech stock but need a SAKO AV action. Know of any or any donor rifles around? Passed on a 7MM RM in SAKO AV several years back. Should have bought it.
Same old life's lesson. "If I knew then what I know now ............" I remember buying new SAKO actions only for under $375 then they quit making them and today I have not seen any in any style for sale actions only.

Dave

Bob,

If I EVER build another 7mm with a capacity larger than a .280 Ack Imp; It will be .338 RUM necked to 7mm in 7mm Dakota dies. (And, Of course, shortened to 2.50"...) Only difference from a 7mm Dak is that one won't have to open up the bolt face. Brass should be substantially cheaper, as well...

Edw

Bob,
The 7mm Dakots has been on my radar for sometime but, as you allude, too rare to make me want to build a rifle for it.
The 7mm Weatherby, freebore and all, is on top of my list.

Grasshopper, I never thought of doing it that way to be honest....I am not that creative,but it would get you to the same place for sure I think.

Dave I have not seen a Sako action in quite awhile myself....one way to do it would be rechamber a Rem 700 KS mountain rifle...I think that would work if carefully done.Or a Sako...IIRC they are long actions too.

Grasshopper,

I'm working with a M-70 Classic Stainless that I had redone as a 7mm Dakota, 24" Lilja.

The 7mm Weatherby is interesting, but by most accounts, produces little over the 7 Rem Mag, and what is gained is due to freebore and higher pressures.

If I can get a 180 Berger to 3100 fps from the 7mm-300 Win, I'd be a happy camper.

Doug,

Are you saying that you expect the 7mm/.300 to outperform the 7mm Dakota? Not that I don't believe you.... I just thought that the cubic capacity of the the Dakota case was larger than the 7mm/.300.

Kinda blows the theory of the short/fat... Doesn't it?

Edw

PS: Please understand that I'm not trying to sway your cartridge choices in any way. Rifle Looneyism being what it is...

Dave... PM Sent..

No, the Dakota will be faster.

Just wanting to play with a wildcat that has my interest.....for the moment...

But if I could get 3100 fps with the 180 Berger, I may send that Dakota down the road....

Do it on the .375 Ruger case. 1

[quote=nyrifleman] Just wanting to play with a wildcat that has my interest.....for the moment... [quote]

Gee... Isn't that what all of us Rifle Looneys do?

Well... I had my flirtation with the 7STW... (4 of them to be exact...) Note that I tensed that in the past...

Rick, I had considered it, but the case capacity calls for a 26" bbl (as does the STW).

Why not just build a Wby??? Call it a Weatherburn,...if you must..

Hell, call it what ever you want..

This is just me and trust me I've been guilty of this b4 as well but if you get that 180 Berger to 2986 or 3055 and or 3100 it really don't matter. Any of those speeds will need dotz or turrets to do the kind of long range work that bullet was born for.

Point being, don't worry yourself too much about 3100...

Dober

Dober, I made the mistake of re-reading the Hagel article last night.

So what do I have to do to a M-70 classic (currently a .300 Win Mag) to make the Mashburn a go?

Pacnor barrels for the "7mm Super Long Mash", which I assume is the Mashburn.

If so.......a #3 fluted perhaps?

First off order the dies, then get your action to a smith with a reamer. I'd let you use my reamer but Bob already has it @ his smith.

Other than that it's get a barrel and have your smith do you work. If you do it let me know and I can get you a fair amount of load data. A fluted #3 would do you just fine I imagine, do you know what it would mic at the mzl?

Dober

(and yeah it seems to me that PN does have a reamer)

Dober
Sorry for the delayed response works been crazy. Im getting 4-5 loads before the pocket is done.

I spoke with McWhorter rifles yesterday.

With a 24" bbl and the 180 Berger they expect to see 3k with the 7mm Weatherby, and 3050 with the 7mm-300 WM, both "conservative" in their words, velocities should be higher.

I've sent a PM to RinB, hoping he'll share his experiences.

4-5 is a bit better than I expected, I'd think they'd beginning to get loose around 2-3 @ 3100. But each gun is different for sure. Just my way but if you're at 4-5 you're not on the ledge but darn close. And then again this is just my way but I'd back it down to 3K and you'll get better brass life and more margin for error on the pressures.

I like to use a load I can run 12 mths a year and that's one that I'd bet will be a skosh warm come 90 degree days. Not that I haven't been there and done that b4..

My experience has taught me that off this type of case (7 Wby, Mashburn, 7/300 win) that once you get to 3K it's time to call it load developement done and get to it.

Lastly, I see no advantage to trying to get another 100 fps. This bullet is for truely long range (500-1K) and for that kind of ranges one needs turrets so another going for another 100 fps will only give one more challenges than they need sooner or later.

Summer temps soar, and you hit a hot lot of powder and....well you get my drift.

Bottom line, I tend to encourage people to be more conservative than I once did. Mainly cause I've learned that the last 100 fps is not always the smart thing to go for.

Lessons over, and I apologize in advance..

Dober

Warren Page got 3050 fps. with a 175 and was happy. Plenty power.

That's true he did and if I recall right he did it with a 22" tube....ouch

My 3 Mashburn barrels would all do 3K with 175's and R25, 3050 was top end and 3100 was getting near the ragged edge.

This is just my way but I go to top end and drop it back 100 fps. This helps me with heat as well hot lots of powders.

Dober

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....

I'm thinking you're gonna love the 270 Bee. Like I mentioned b4 if I wasn't such a Mashburn lover the 270 Bee is what my old 700 would become. What barrel, action etc?

Dober

Dober,

Winchester 70 Classic Stainless, either a #3 0r #4 Pacnor, 26" fluted.

Kool, stock? I'd go with the #3 and cut it to 25" just for good luck...grin

Dober

Stock will either be a Hill Country "Bridges" McMillan or an Echols Legend.

Nice!!

Dober