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

No, not a misprint....

2001 or thereabouts brought us the 7mm Whizzum, aka 7mm Winchester Short Magnum(WSM)....a sorta stout,vertically challenged affair and really a copy of a design that originated back in the 50's in the Gradle Express line

But also back around the 1950's a guy from Oklahoma named Art Mashburn(actually known by OU76 who posts on here)gave us,after much experimenting,the cartridge known as the 7mm Mashburn Super Magnum,aka 7mm MSM.The Gradle Express series went nowhere at the time, but the Mashburn was popularized by such notables as Bob Hagel and Warren Page back in the 50's and 60's;and by our own Mark Dobrenski today.

(Worth noting here the 7mm Weatherby was around in proprietary form, but Roy gave his barrels a 12 twist which did not stabilize the 160 gr bullets that LR elk hunters wanted to use.)

Unlike the WSM, the MSM is a long, leggy affair that can fit handily into a 30/06 length action,but adapts nicely to a H&H-length action as well, which means any run of the mill Remington 700 or Winchester M70 can be adapted to it.

After fully half a lifetime (30 years) of using the 7RM, I wanted something a little different in the way of a portable,relatively lightweight all-round BG rifle,with the ability to "easily"(a key component)push a 175 gr 7mm bullet in excess of 3000 fps,a 160 gr from 3150-3200 fps, from a 24" barrel,with moderate powder charges,and would not kick me into next week.Something "optimum" but not too much,as with the 7STW and the Ultra Mag,both of which seem more at home with thick, heavy 26" tubes and/or gobs of powder.The 7 RM with various throatings came close in a 24" barrel but I sometimes thought I was pushing the envelope;I always thought the 7RM could use more capacity and a longer neck.

After watching Dober's results on here with the Mashburn,and talking to him a good bit,I sent a #2 9 twist Krieger to Gene Simillion,along with a M70 Classic action from a 270.A friend from back here did the same thing.Dober was kind enough to lend us his reamer and I am still using Dobers dies until mine show up from RCBS(we had an ordering snafu with another die maker which delayed having dies delivered on time)....

I told Gene I wanted a 375H&H-length box,and he got me an Echols box which easily swallows cartridges loaded to about 3.575 OAL,with room to spare;throating was set up for a 160 Partition with base of bullet even with base of neck;the 175 seats a bit deeper into the case.

The stock is an Echols Legend Edge;very nice!

So what did I end up with here? Well, as Gene said the cartridge is not about ultimate speed;it's about building a portable package for mountain and open country hunting with an optimum velocity level, with long 7mm heavyweights, reasonable powder consumption,and flat trajectory,and without the weight and recoil of a 300 magnum.Near as I can tell, he described it spot-on....

Load development is still in progress but what I am seeing so far is:

Dobers fireform load of 65 IMR 4350 139 Hornady at 3160 to 3190,(which to me is a 280AI in a similarly configured rifle. The Mashburn will of course push a 139-140 gr bullet much faster with full loads).

After fireforming, you have the blown out Mashburn.And 72.5-73 gr H1000 gives the 175 Nosler Partition 3040 to 3075.This bullet has an SD of .310 and a BC of .519.According to the Nosler tables, when started at these velocities,it has about the same trajectory as a 180 gr 30 caliber Partition started at 3200 fps...(the 30 caliber taking a bunch more powder and recoil to get there). My shooting so far is showing this to be true.

Or if you like plastic tips, this cartridge easily starts a 160 AB at 3150-3175 with about 75 gr H1000.I see no logical reason to go with any bullet weighing less from this case,although you can certainly do it.

As to recoil? I have sat behind a bunch of blown out 300's over the years.In comparison, with its' heaviest loads, this rifle is a cakewalk.

Pretty hard to justify the wildcat in light of all the other 7mm's that provide similar performance;but this one "gets there" in an efficient fashion,being just enough without being too much, yet not lacking the capacity, so that one does not have to stand on it to get the desired velocities,as with smaller 7 mags.And the MSM does this in a 24" barrel to boot.

I have had a 7mm Dakota, which is similar,but did not like being tied to one source of brass, and a case not easily formed from anything else.The MSM can be easily formed from 300 Win Mag cases,available anywhere.And if I get tired of the wildcat,a 7 RM is only a rebarrel job away.

Looks to me like Mashburn,Page,Hagel,and Dober knew (know)what they were talking about,even back 60 years ago!A very cool cartridge!

Wish I had built one sooner!

Because people are going to ask.................






This makes the "ugly stocked" M70 in 7mm Mag that you have redundant. Send it over Robert.

Scott, TFF! Laffin here!

Thanks for that!I know how they wail to the high heavens on here with no pics.

To me, it makes lots of things redundant.....

Thanks for sharing your project, ole Dober knows the Mashburn all too well. And you'll be giving the critters the Mashburn dirt nap soon too!

MtnHtr

always thought the Mashburn would be the best 7 mag in creation , but it seems to me that if pushing 175s over 3000 and 160s to 3200 . then recoil has to be alot like a 300Winny ?

SD: It really isn't...it is just "lighter" somehow..hard for me to explain,and don't get me wrong, it recoils.... but I notice a level of muscle tension needed with the big 30's,and a level of fatigue that sets in with the 300's, not present with this and the 7RM.

Might be nitpicking I know(much of this project is ,

....but even Gene said it was a pleasure to shoot compared to the 300's.So at least I know it ain't just me

At 60, I am a lOT more recoil sensitive than I used to be

Bob, do you see any advantage over the weatherby chambering? (one I've thought about) I always "felt" the remington mag was "not quite there", but close!

Bob,

Good luck with the rifle. Sounds very well thought out and just what you are looking for. I understand the recoil issue but at those velocities, there must be some kick, how is it in comparison to the 7 STW's you have shot?

Don't feel bad, at 41 my recoil tolerences are not what they used to be

By the way, I love the name, Mizzum

pat I have never worked with a 7 Weatherby,and know the manuals show it similar to the Mashburn;but i also know it has about the same capcity as the Remington case,so I really can't explain how the weatherby gets where it does,except due to the freebore,a 26" tube,and Weatherby-type pressures.

I have had a few "long throat" 7 RM's and they nudge right into 7 Weatherby load data territory.But again, I always felt I was leaning a bit hard.The thing that struck me about the Mashburn was how "easily" it reached these velocities.And velocitiy variations are very low,maybe 10 fps in a 5 shot string,at least with H1000.I think Art Mashburn did his homework.

Bob,

I like my long throated custom 7mm Weatherby,but find the 7mm STW to be a lttle much recoil wise.

Likewise.I can do the 300 win mag,but the 300 Weatherby is uncomfortable.

All of this had me thinking about a 7mm/300 Win.

My gunsmith has dies and reamers for this one.

What's the difference between the Mashburn and the 7mm/300 win?

Is it just a 7mm/300 win Improved?

Chip; Thanks!The STW's I have fired were the M70 Classics,longer, heavier rifles,so it is hard to compare;this stock design of D'Arcy's is very good at mitigating rcoil in a magnum chambering.i fired the rifle off hand yesterday and it is very pleasant,not inclined to jump back hard or climb during recoil.It is more manageable than the 300's, to me anyway.

BTW I gotta give credit where it's due....my buddy Matt took the other Krieger #2 and built the same rifle,metal by Gene,and stock work by Charlie;veddy nice also and Charlie did a great job on the stock.

Yesterday at the range Matt said...."I'm gonna shoot the "Mizzum"........I said "The what?"...he said. "You know,the Mashburn Super Magnum, the MSM!" I laughed!

Britt; It is a necked down 300 WM case;first pass with the form die forms the new shoulder and longer neck;second pass with the trim die brings the neck down to 7mm(no trimming required,then through the FL die to tighten up the neck.(Dober had to walk me through all this).

FFing the case blows it out to a straighter contour;the 300 Win Mag has more taper and a shorter neck.

The longer neck is part of the beauty of the Mashburn design, plus the straighter case,which gives a skosh more capacity. The longer neck helps if you build with a longer throat,as I did, because I can seat even 140 gr bullets close to the lands.No bullet I have used is seated into the case,except the 175, and that very little.

The 160 AB is seated to about 3.575 OAL;and the 175 Partition to about 3.515,due to the ogive mostly.

At the end of the day, I doubt there would be much practical difference between the Mashburn and the 300 WM necked down.

Do you not have one anymore?

Interesting build; thanks for sharing.

I went to a Mashburn's gun store in OKC as a kid. I wonder if it was the same guy.

Sounds like a good round Bob.Wanna race for pink slips?grin

Sounds suspiciously like a .284 Jarret designed by the greatest gunmaker in the whole wide world

Gene S. ?
M70?
Echols?
Mashburn?
Dober?

WTH were you thinking? Sounds like a, er, well, ah, hmmm, you know, ah, well, eerrr, a pretty sweet rig.

No doubt.

Mike: I won't bet....you might win

Karnis: I did the best I could.....

oldelkhunter:Seems Jarrett is about 50 years late...gotta admire his taste though......

MtnHntr:There is no doubt Dober knows the Mashburn....he helped make this a pretty easy deal,and was spot on in loads vels, etc.he and Gene got me started really well...been an easy wildcat to deal with.

Very nice rig.

Bob, will this new wonder rig be heading west soon? I sure like the looks/stats of what you put together! A well thought out project for sure.

Good job Bob!

About time we saw this rifle IN pictures!

Are 175's going to be thee bullet?

Hillbilly; Thanks I think it turned out pretty good....easy cartridge to work with....no BS...just gives the promised velocities easily.

Randy, yes I will take it to Wyoming
Zeroed for the 175 to hit POA at 300 yards, it prints the FF load to the same elevation at 300 yards;but slightly left.

The 160 AB and Partition go to the same POI at 300 yards but about 2" higher than the 175. I would have to rezero for that load....no biggie....

SU: Thanks! Hell all I did was pay for it ....this was a collaborative effort with Dober and Gene providing all the guidance and building.I told Gene what I wanted, specified throat,mag box, etc.He is a dream to work with;a real rifle guy who "gets it" when you mention something....immediately.

Dober was a huge help,advising on the cartridge loads, providing reamer to Gene and dies to me to get mestarted ay great inconvenience. he knows his way around the cartridge and between he and Gene, load work was easy.

Also JWP gave me some good advise on powders as well....I had a LOT of help.

Tell ya what....now I understand what Page was saying about that 175; and he had the old semi-spitzer, not the newer one with that 519 BC,which is pretty darn high for a soft-point Partition.....you could very easily use just that bullet for everything.I have no prior experience with it but Dober gives great reports on it;it shoots flat at 3050,and groups at 100 yards have gone 1/2", if I am on my game.

Looks very nice, Bob.

Pretty hard to go wrong with anything that Hagel put his blessing on..............

IIRC, Dobrenski knew Hagel, at least casually, & met him a few times; prolly some inspiration there.

Glad it worked out for you; if I ever do another version of a Big 7, it would most likely be a Mashburn, if for no other reason than just because.

What's the weight of that rig?

MM

Looks like a dandy rifle Bob.

Great looking, and very capable!

Have fun with it.

Bob - very nice.

I've threatened to have my Classic re-chambered to the Mizzum - especially since I have a 7 SAUM. Is it guaranteed not to miss?

7mm Mashburn's are for complete nut-jobs. I should know, I'm friend's with one... (grin).

BTW, beautiful rifle Bob!

It do shoot pretty flat -27 at 500 for the 175 started at 3050 and -25 for the 160 Partition started at 3150. Plus calculated recoil of ~ 30-32 ft/lbs for an 8.25 lb gun.

Huh.........

Bob I can like any cartridge that uses the 300 Win Mag case.Congrats on your new rifle.

Bob,
Great looking rifle and a cool cartridge. Can you give more specifics on the metal work that Gene did (have any pics of that?). What contour barrel..is that an Echol's contour? Also how was rifle bedded..are you using a pressure point on the forend or free float.
Terry

Terry:I'll try to cover that stuff, best I can.It's written down somewhere

The barrel is a #2 krieger CM that I had here.I can tell it has been machined to sharpen the transition from the chamber area into the barrel shank,just enough to give a definitve edge.He cut and crowned to finish up at 24".The barrel has also been "drawn" (and polished?)before it was blued;you can tell holding it to the light because there is not a wave, or ripple in the blue job anywhere...just straight lines;ditto the action.

He blueprinted the action,squared up the lugs, etc,all the good stuff done when barreling up these days.

He installed an Echols H&H-length box magazine,and a Dakota-type follower.My first round down sits on the left rail.Extractor is a Williams and you can put a cartridge on the bolt face and swing it around;it won't drop a cartridge..... and who knows what he did to the extractor/ejection system but it feeds, extracts, ejects reliably everytime...I have rapid fired it and it gooses empties a long way.I am certain he modified the ejector/bolt stop to handle the H&H length cartridges.

Dunno what he did,but the action doesn't "feel" anything like it did when I sent it to him.It feels somehow "tighter",less play and slop,smoother overall.

Bottom metal is Williams and has been recontoured so that the trigger guard tapers to the rear toward the back screw;nice touch...it's also nicely blued and polished.

Mounts are leupold DD's which I requested;they are ground to the receiver.He changed screw spacing on the bridge;I think this was done because he machined the bridge to allow use of a H&H-length round(This is what I like about Gene;this is a small item that you don't have to mention to him;when you say set it up for H&H length, he knows EXACTLY what is required;does the whole thing "right").

The bolt handle is the original M70 Classic, recontoured.He notched the cocking piece shroud so that in the fire position the arm of the safety makes no contact.Nice little touch.

I am sure he machined/polished the bolt body as there is no visible seam where the bolt handle is fixed to the bolt body. The bolt body is jeweled,which I like.Bolt release is built up and checkered.The trigger is the original,but he contoured it to a slender profile.It really feels great and breaks like glass.I asked for 3.5 pounds but whatever....from off hand it broke nicely when I said "go".

The sling swivel studs are a nice two screw design,perfectly inletted.There are a lot of subtle touches in the rifle that make it a nice package.

Overall everything is just tighter,slicker,nicer feeling than when I sent it to him.It's apparent that he paid a lot of attention to small details here as there are lots of little touches making a nice package.

I knew going in that a #2 chambered for a cartridge of this power was on the light side for a powerful high velocity cartrdige;and the Edge stock is light as well.I had heard that D'Arcy does not like to use an Edge on anything bigger than 300 Win Mag.I suspect Gene felt the same way.I could have gone heavier in both the barrel and stock but figured it would shoot regardless because it was put together well...but I wanted a portable rifle that while not being too heavy,was not too light either.That said, I knew I was on the ragged edge with this chambering.that said, this ain't a BR rifle....it's meant for hunting.

It shoots very well,not to BR standards,but groups with the form load and the 160's are sub MOA and enough 1/2" 3 shot groups show up to know I am likely the limiting factor.

When I got to the 175's though, at full velocity, the wheels fell off...groups were in the 2" range.Also, shot from my hands ,field prone at 300 yards,it showed a tenedency to double group,ie....in a 5 shot string,the first shot was always where it should go...but the others would follow a predictable "high shot/low shot" routine.And groups were about 2 MOA.I suspected I was building a pretty big fire, lots of tourque with that long 175 at high velocity.This occured only with the 175 gr load.139's and 160's did not do this.Apparently I hit the wall with the 175's at full velocity.

Without calling Gene, I pulled the action and cut a small swatch of adhesive-backed pipe insulation;the squishy neoprene-type stuff,and set it an inch back from the forend.This cured things and the first group at 100 yards with the 175 Nosler Partition put 3 shots into 1/2".I then fired it field prone at 300 again and groups went right to 3-3.5",and the "double grouping" disappeared.

I called Gene and told him what happened and he said he doubted the barrel and forend were touching, but likely what I saw was stock resonance;said he had seen that before from light ridgid stocks and slender tubes.Apparently when riding the bags,this is attenuated;but from my hands there was not enough to bring it under control.He was curious about how I came up with the solution,and equally curious about the material used..... :)He said he thought I was on to something....

I have shot the rifle several time since;no shift in POI and good groups. I fired the 160 Nosler Partition and AB at 3150 yesterday at 300 yards;group was about 3" with each; no discernable difference in accuracy from a practical standpoint.Keep in mind this is with my left hand supporting the rifle,and no rear bags.

MM. I dunno because I have not weighed it....but I can tell handling it that it is more than my 7-7.5 pound 270's;less than my M70 Classic in 7RM.I am guessing it at 8-8.25.I also can tell it will not break me down.Not sure I would want it any lighter.


bwinters:I think Brad is right....you gotta be a nut case to build one....

Given all the 7 mags out there,and the STW being pretty much the same thing,it is pretty hard to justify unless you are wedded to the notion that you just want something different, and want to have some fun,while getting a tick up in velocity.Will it matter on anything you shoot?I doubt it...Will it wok really well?We all know the answer to that.....it will work splendidly.Twoof the most prominent riflemen/hunters of the 20th century used it everything from Asian Mountain game,to grizzlies,sheep,elk, moose, etc.gene said he loved that long 175 gr at high velocity,said it would penetrate like crazy..

It is probably as rational as building a 280 AI But hell, the fireform loads do what a 280AI or factory 7RM loads will do,in a rifle configured about the same.....with the Mashburn, that's the warmup

Pretty cool stuff there. I used a 7mm Rem mag with 175's from both Nosler & Sierra for a few years. Really enjoyed that combination, it worked very well for me.

Guy how did the Sierra's do for you?Kill game with them? I have a pile of them.

Just a random thought here. Wonder how a 7mm Remington case with a 40 degree Ackley shoulder and long throated for the 160-175 bullet would compare to the Mashburn ballistically?


Such a setup would make for easier case forming.

Should try the 150gr Nosler Partition in your new rifle Bob.I promise, you'll love the results.

Bob, that Echols stock is a thing of beauty. Makes me want to throw away the edge I just got for my M70

That would sound a lot like a 7mm Sharpe & Hart; performance is good, but a tad below the Mashburn, IIRC.

MM

Bob, thanks for sharing your project with us. I have never tried the Mashburn, but I had one of the first 7MM-3000WM in my neck of the woods-1975 or there about. I still use a 7RM some. However, recoil has begun to bother me some and I don't like muzzle brakes or heavy rifles. So my solution to the ideal elk, deer round is the .280AI. I can push the 160gr Nosler Partition at 2950fps without torturing my rifle or cases and recoil is not bad at all. The rifle is on a pre-64 Mod.70 with a #2 Krieger, it's stock is a well finished piece of English walnut with good color contrast and well done checkering. I'm going elk hunting in a couple of weeks so I did a final zero check yesterday and got a slightly less than 4" five shot group at 300yds.

That is one fine rig. Cool factor is off the charts. Since no one has claimed it, I will. DIBS.

Bob that is sweet with the cool meter pegged!

Very nice rifle Bob. Interesting fix for the stock resonance.

Bob, that is a beautiful rifle! Very, very well executed as only a Simillion, Echols, Penrod can do.

Congratulation!

Mind posting a pic of the cartridge?

Nice rifle.

Does anybody have a few pics of the cartridge case itself, especially in comparison to a 7mag, etc.

Hillbilly: I have not formed an Ackley shoulder,but have "long throated" a few 7RM's and generally they work a lot better than a standard Rem 700-type factory throat.There is not a huge velocity gain,but I found the cartridge a lot more tractible as you got to max than with some shorter factory throats;I think barrels and throats are behind a lot of the difficulties a lot of guys see with the 7RM;why many will hit a wall and the velocities are not quite up to what one "expects" of the cartridge.

Of course if you throat for the 160-175, you compromise bullet/land relationship with 140 gr bullets,because thet have to jump to the lands.Sometimes this works OK and sometimes not.

It is really as much the longer neck,longer bullet seating,and a skosh more capacity that makes it easier to hit these velocities in the Mashburn,as opposed to the Remington...the Mashburn just lets you get there easier near as I can see so far.There is not a real universe of difference;but if you have struggled with the 7RM to get the vels you see from some sources,the Mashburn will be appreciated.

oldelk: That Echols stock is about as nice as I have seen,especially for a magnum chambering;the stock could be one of the reasons it does not seem to kick so much......

Gene tells me D'Arcy did the paint job on it,which is a two-tone black/brown.

SuperT:Sounds like you are GTG;I suspect that load will put an elk hoofs up in short order! And as you note,with less recoil as a bonus.

DD/Huntr; I will try to get a few pics of the cartridge through the forming process this weekend.

There is more than one way to skin the cat and I have had a couple of conversations with Bill Steigers at BBC;he is instructing me on how to fully form the Mashburn case with tumbling media(corn husks),large pistol primers,and Bullseye pistol powder.

That means I can form cases from new brass by firing out the back door at the house...the neighbors will love it,but hey this is NH...there are always guns going off here!

Thanks for the information. I have never chronographed any 7MM Remington factory ammo that was even close to the factory listed velocity and only one 7mm I have worked with came near the loading manual listed velocities before hitting pressure issues.

This 7MM Mashburn of yours has set me to thinking. That usually winds up costing me money

Oh, how is the cost of the Echols stock versus a "standard" McMillan?

AZ: Th double groups had me puzzled;something changed when I went from the bags to a "softer" medium, like my hands.I repeated the test a few times to make sure it was not me.It wasn't.

Thinking on it I felt the barrel didn't need "up pressure" so much as it needed something to "dampen" vibration,since it had shot well with the lighter bullets.So I thought about the pipe insulation. That cured it.

I have noticed with these precisely tuned sporters with light barrels, that they really shoot well,but equally true that if you feed them something they do not like,they will let you know right away...a guy has to figure out what is wrong.

hillbilly: They are available through D'Arcy at pretty much the same prices for the stock as for the mcMillans IIRC. A friend bought three,and sent them to CAS for paint and bedding.

Thanks. I didn't know if they were more expensive than the standard ones.

Hmm.....never heard about the round could someone tell me a bit about it..

Dober

The nut-job appears (grin)...

Good looking rig Bob, well cept for the Model 70 part.......grin


Anyone got a pic of said cartridge next to say a Remington version?

Nut job, panache, style.....same o same o...

Dober

Bob-the 160 Sierra HPBT is one heck of an accurate and game killing son of a gun! Add 7828 of course..grin

Dober

Was thinking about Cole's first lope trip five years ago... the old Mashburn whacked and stacked lopes in style.

And your shooting wasn't too bad either... (grin)

Yeah every once in a while a blind dog finds a bone...

Seems to me you whacked a lope that day, and got whacked that day yourself..

Dober

(Hitting the lake in a few, call if you wish)

Thanks Scott! It was tough choosing an action, but the M70 was all I had lying around........

Skane has pics of the 7RM and Mashburn compared,both empties and loaded rounds.Sure he will post for me when he sees it on his email.....

Hell,why I am I doing all this explaining?.......Dober is the Mashburn guru.....not me......I'm the "student"

Dober you walked me through this project....thanks! I have mostly not shot anything else since it showed up!This thing is almost the most fun you can have standing up

BTW, I tried the FF method Steigers and RinB schooled me on....result is perfectly formed Mashburn brass,which I loaded with 75-H1000 and 160 Partition.Going to the range with it now.

That one of them there controlled feed jobbies? What's that about?

Been looking forward to hearing about this Bob.

Congrats, that's a great looking rig.....although I'm kinda surprised you didn't go with a McSwirley

ny: I left the stock color up to Gene and D'Arcy...I think it came out nice!

Bob,
Would love to see some additional pics of the rifle!

Nice project Bob.
Good when a plan comes togeather.

dave

Dave:Workin' so far.....wonder how it would do with a GS Custom?

Thanks, Brad.Handsome is as handsome does and near as I can tell so far it performs nicely.Being a rifle "student"(always learning),and a bit of a history buff,it's an interesting cartridge to me and fascinating when you think about how it got started....and how well it turned out in a day when folks did not have access to the info and technology that we now have;even Warren Page had to send cartridges and rifle to Remington to get the velocity info that any of us can get in an afternoon now,on our own.

Tastes in cartridges shift like the wind and guys are constantly running around to newer,different cartridges.I think a lot of this activity is circular, like fish swimming in a barrel,and lots of new cartridges are not all that "new";the design or performance parameters having been set decades ago.The Mashburn is a good example of that....witness the "new" 284 Jarrett,or the STW.

Goes to show you can't really know where you are unless you know where you've been.....

I thought it was poetic justice that my first shot over the chronograph with a 175 Partition measured 3050.....precisely what Page said his old rifle did at the Remington plant back in 1959....


And yet there is newer good stuff today.....personally I think the 6XC should replace the 243 in short action sporting rifles....just a better, forward looking design.And old Bill Steigers told me the other day if he were looking to build a hotter 375 than the H&H round,he would not bother with his old favorite 375AI,but would move right on up to the 375 RUM with its' good, modern brass and plenty of capacity..

.....this from a guy whose clients were blowing out 404 Jeffrey brass and necking it down to 30 caliber a couple of decades before the 300RUM saw the light of day...interesting to think about and there ain't much new under the sun!

It would be a boring old world if everyone shot a 30-06!

It's great to read of the enthusiasm that another rifle can bring.

Superb writing such as BobinNH's and that of others makes it so enjoyable.

Your Mashburn would turn 120g GS-HVs into screaming missiles of destruction.
It would work just fine Bob.
They also have a 140g GS-HV but im not sure that your 1-9 twisted barrel would do the trick.
Person would have to call.
The lighter bullets dont seem to be theme here in this project.
Betcha a 120 grainer wouldn't kick as much as the stuff your shooting.......


dave

Dave is 9 twist too slow for the 140?

I figured I'd give it the traditional stuff for now

1-9 should be just fine short of a javelin.

http://www.gsgroup.co.za/284140HV189.html
A bit confusing.
Gina could clear that up in no time.
The 140 HV should work fine.
As monos they are long for caliber.
.... A 140 HV out a a Mashburn......


dave

I'm guessin' the same

7RM and Mashburn pict from Robert.

Thanks Scott!

Left to right is a 7 Rem Mag empty;a 300 Win Mag after a pass through the Mashburn form die which starts to form the shoulder and lengthen the neck;a Mashburn case afer a pass through the trim die,which brings the neck to 7mm; a loaded 7RM round; Mashburn case loaded with the 175 gr Nosler Partition.

Bob,

I have killed a pile of deer sized citters with 160 Sierra Gamekings in a long throated 7mm Rem Mag using max loads of R22. This is a pretty tough bullet and it pretty much exists every time. I substituted it for a 160 Nosler Partition for use on paper and later tried it on game. Frankly,I never could tell them apart,quick kills and exits.

John Barsness uses the same bullet in his 7x57 and speaks well of it.

I also used the 150 Sierra Gameking out of my Custom 7mm Weatherby for long range deer and antelope. It has worked well at what I consider long range,350 to 500 yards. So far nothing has walked away from one of these either.

Hope this info will be useful.

RD

Yes it is Britt;thanks for that. I have been burning Partitions to get to a hunting load,but if that Sierra works I may run those....got several boxes.

That is a good looking rig, I hope it turns out to be a lucky rifle for you.

Why the 175gr Bob?

StrayDog: Thanks! It gets its first run in Wyoming on the 15th.

Mike as you know,about everything in 7mm works good in a big 7,provided bullet structure is suited to the task.This leads to a lot of jumping around One bullet for a bunch of tasks has its' appeal.I have used the 140 and 160 a good deal in the past,but not the 175.

I won't stick strictly to the 175(I'm taking 160's to Wyoming),but keep in mind that it certainly has a lot going for it....a high BC,noted for deep penetration,reliable expansion,and suited to anything you can use a 7mm on.

Plus this cartridge(in truth most all 7 mags) starts it fast enough to qualify it for long range(at least my brand of long range)on about anything.....its' trajectory started at 3050 matches pretty closely to that of a 300 Weatherby 180 Partition started at 3150-3200 or so.Flat shooting and hard hitting enough for any rational purpose and still manageable.

I also have a bunch of 160 and 175 BBC's that I will use.And none of this prevents me from using a TSX,etc. I even have a box of 150 Etips downstairs

Good Morning to you Bob.


Yet to try a E Tip in my 7's.Prolly won't unless a box of 140gr slugs hit my hand.I used to be a heavy bullet guy myself..Know where your coming from.

I've been known to run a 175 Noz from time to time, it works, hard to believe I know...grin

My main stock has been the old Semi's, they shot very well and killed very well as far as I wanted to shoot.

Dober

Bob,
I havn't had much luck with accuracy from 175's in my 7 mm barrels. I use to load 175 Sierra and Hornady for my brother's Savage 110 and it loved them. It didn't make sense to me because his rifle had a 1-10 twist, which proves you never know until you start shooting the loads.

When I was a youngster in my 30's there was an older gentlemen in camp that had a Rem 700 and he shot 175 grainers for everything from elk to antelope. He had it zeroed at some long distance like 500 or 600 yards and just aimed a few inches lower on the animal at everything closer. Another thing that didn't make much sense to me at the time, but he was used to it and it worked for him.

4 a long time I used the 175 Semi for all that moved as well, may go back to it for a while as it sure has some panache..<g>

The 175 Sie has been a bit picky when it comes to accuracy for me but the 175 Horn has been incredibly stellar!

Dober

Dober I got a funny feeling that even in this day of super bullets, that old 175 might just be one of the superest of all.

That thing is as long as a panatella!


StrayDog; I struggled a bit with the 175,too in the 9twist barrel....until I figured what was going on...but they are shooting fine now,and this rifle puts them right there with the 160's at 300 yards.I could use them pretty much interchangeably.

There is only about 100 fps difference in the velocity between the two......so a guy scratches his head and says..."Geez,why do I need anything but the 175?"

yeah I've given a critter or two the old panatella dirt nap..grin

Dober

I have heard of the 7 MM Mashburn Magnum, and also a 7 MM Mashburn Super Magnum.

Are they the same cartridges?

I have a Speer Reloading Manual for Wildcat Cartridges, dated 1960. It has 7 MM Mashburn Magnum loads listed. This is where I got the Mashburn Magnum and Mashburn Super Magnum. In one place it is called the Mashburn Magnum, and a page or two futher on, it is referred to as the Mashburn Super Magnum. I have always wondered if they were both the same cartridge.

I used the 175 partitions on a variety of game in Namibia last year and they produced the nastiest looking wounds I have seen. You have to go to 375 to notice a consistent difference. I was shooting them at about 2900 and at 3050 they would only be better and flatter shooting as well. Reminds me of an old girlfriend who said "I am a sure thing and don't take advantage of it". Still have the big 7 but was stupid re the girl.

Bob,

Love that 7mm Mizzum!

Congrats on the new rifle! Hope is it all that you expected and more!

I assume as it uses D'Arcy's mag box that it holds 4 down?
How do you like D'Arcy's Legend stock? I am thinking about ordering one for a similar project.

I think it's reasonable to say we could use a few more pics of the rifle and perhaps a pic or two of the Mizzum round would be nice....and maybe a recently dead critter and the new rifle...?

Best Regards,
Dave

I would also love to see some additional pics of the rifle...

Guys I will do the best I can on more pics....and hopefully if I find the Wyoming buck I'm looking for I can get a dead critter .....I just got the rifle two weeks ago.

Dave there are pics of the cartridge that Skane posted.