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

This turned out to be a nice re-birth thread.

I mean, who doesn't like a good 7-MM or two or three. I guy can never have too many.

Totally agree with that. The only problem with having 1 Mashburn is it makes me wanna have a 2nd one just in case...

It has been an awesome cartridge to work with. Mine is an old beat up 70 XTR that was rechambered to 7 MSM.. It shoots pretty danged well as is and hunts fine, but a truly nice 7mm MSM is high on the want list.

The only reason I stopped at 1571 yards that day was because it was the longest target we had set up for which I had scope travel

The Mark 4 only had a 30mm tube. The new Mark 4 should get me to well over a mile. The ballistics of the 195 grain Berger at 2970 are better than the .338 Lapua shooting a 300 grainer.




Hey Beretzs,

I hear you're using RL-33 with the 175's and doing well. I might have to try some with the 195, but it's shooting so well with H-1000 I'm afraid to try! 100 more FPS may or may not be worth it...

That's impressive regarding the 338 Lapua. A lot of return for the recoil dished out.

How long a barrel you got on the 7mm ?

if you run the numbers thru JBM , I get ......


7mm drop @ 1000 yds 23 MOA , drift @ 10 mph 48.7 MOA , 1458 ft lb energy

338 drop 25.4 MOA , drift 48.5 MOA , 2102 ft lb energy


I used 2800 fps in the 338 with the Berger 300 gr elite hunter , doable in a 26 barrel


it looks to me like the 7 wins ever so slightly in trajectory , the 338 shades for wind drift , and the 338 simply crushes the 7 in energy delivery , which you would expect.....


so what makes the 7mm ballistics *better* than the 338 ?

195 Bergers out of my rifle







.338 Lapua 300 gr Matchking @ 2800 per Litz

the Bergers pack a better BC than Matchkings......seems a fair comparison would be Bergers to Bergers ?

Whatever!

A 7mm is a 7mm,and a 338 is a 338.

Point is well made by comparison. The Mashburn with these high BC bullets is an impressive, modern performer,and the performance comes with substantially less recoil than a 30 caliber or 338 with the same flight characteristics.And with bullets heavy enough to be reliable on most any open country animal.

That it "suits" in a 60 year old lightweight Mauser,or a specialized,modern LR rig demonstrates its adaptability.

Yeah! But the 30's hit harder.

Sure...with a price in recoil. That they may "hit harder", to the extent we can quantify that,is because its bullets are heavier. That makes sense.

But cranking those equivalent 30 caliber bullets up to the same speeds as the equivalent 7mm(to get the same flight characteristics for sure hits in open country),and we find we need a bigger case holding substantially more powder.

Take a simple example of the 300 Weatherby. It takes 83-87 gr of H1000 or 7828(two good powders for the 300 Weatherby) to move a 200 gr partition or AB at over 3000 fps from a 26" barrel.

OTOH, the Mashburn starts a 175 gr Partition at 3050-3100 fps with 73-74 gr of H1000 (similar BC's and velocity).

No doubt the 300 will boot you more in an 8.5 pound rifle.

A buddy took his Mashburn to Wyoming for two seasons, killed a couple of big mule deer with the 175 Partition. He said it killed like his 300 Weatherby. I told him compare a 180 gr 30 caliber bullet at 3200 fps,to a 175 gr 7mm started at 3100 fps. That tells you part of the story.

Even Elmer Keith noticed it back in the 30's with the DuBiel 7mm magnum with 180 WT&C bullet vs the 300 H&H.....

In case we have't noticed, heavy 7mm bullets nudge squarely into the middle range of 30 caliber bullets. No wonder they kill convincingly. The rash of new 7mm is ample evidence that lots of people notice this.

Page noticed this 60 years ago.

Bob , I concede the point that 7mm is very efficient....


what I maybe dont concede is that a Mashburn can kick all that much different than a 300

when you are running nearly 200 gr of bullet at nearly 3000 fps , you are certainly in 300 weatherby territory

I dont know what powder is being used to push those 195 gr pills , maybe RL 33 ? , but I bet its slow and takes nearly as much as a 300 weatherby charge

thus it seems to me it is gonna kick alot like a 300

pushing 175s in the Mashburn at 3 t0 3100 is surely neck and neck with the 300 winchester.....

I'm using H-1000 in a 28" barrel for 2970. There's room in the case, so I'm betting RL-33 would deliver at least 100 fps more.

The problem is, I'm happy.

The rifle is shooting so well with the H1000 that developing with RL33 seems unnecessary.

sd: This business of the Mashburn kicking less than the 300 magnum was pitched in the days she the 300 Weatherby was cock of the walk and the 300 Win Mag did not even exist.

A better way to say this might be that...you get kicked less for the same level of external ballistic performance. That sound fair?

I can tell you that I have shot a lot of top end 300 WM,300 Weatherby, and 7 Mash burn. We frequently shoot 300 Bee and Mashburn side by side as my pal has both.

I joke with him and say "Which would you rather shoot?"

Answer: "The Mashburn".

And, "Which would you rather carry up an elk mountain?"

Answer: "The Mashburn".... It's about a pound lighter.

I can't quantify this in words any better than anyone would see shooting the two side by side. Mashburn recoil is fast...but lighter than a 300 win or weatherby. My rifle weighs 7.5# scoped,and I am a whimpy old man....I cannot manage a 7.5 pound 300 win mag or Weatherby.

Keep in mind that Rick is only burning 73-74 gr of H1000 to generate those velocities with a 195. How much powder and bullet would we need in 30 caliber to get the same level of performance. I suspect we will get kicked a lot more doing it.

Bob,

I have a heavy 12 pound 300 win mag.
I do not like the recoil at all.
My Mashburn gets shot more.....


dave

Dave...could not have said it better! You certainly would know.

Ok just for giggles I ran some data thru the RCBS recoil calculator. Both theoretical guns weight 7.5 lbs, bullets 175 gr for 7 mm MSM., 180 for 300 Roy. I used my own load data, and Nosler for the Roy. My MSM uses 73 gr H1000 the Roy used 85 of several H1000, 7828, RL-25 for similar vel.; 3050-3100 fps.

Recoil for the MSM was 34 and the Roy 38 ft lbs.

I regularly shoot my 7.5 lb. MSM and it doesn't seem to be vicous or unpleasant. YMMV.

4 ft lbs difference.....I just dont think my kick o meter is good enough to detect that difference in a side by side blindfold test.....certainly stocking and fit of the rifle to an individual will make much more difference than 4 ft lbs

I suspect most of ya all that are finding Mashburn recoil alot different are using lighter bullets than 175 to 195

a load ive used alot in 300 roy is about 76 gr 4350 under 180s....so size of the powder charge doesnt always have to be much different

I do think the Mashburn is best of the breed if you want a 7 mag....just enough powder capacity to get what the 7 Rem mag users wanted all along without going to the ridiculous powder appetites of the STW or RUM

sd: I do shoot mostly 160's...with a smidge of 175's tossed in. I have never fired 195's.

I can say that I have fired enough Mashburn and 300 Weatherby to notice a difference.Mostly because I have shot them side by side....same day....and of course I am not implying the Mashburn does not recoil at all, because of course....it does.

Ok, I reran the calculations as above with a 160 gr. bullet and 75 gr powder, gun weight same as above and it produced 32 lbs. recoil.

Pays your money and takes your chances.

Muzzle brakes are nice. Even my light Creedmoor has one.