Home Forums Hunting & Shooting Custom Rifles & Wildcats 7 Mashburn

What kinda twist do you need to get the Scenars to stabilize? Mines sorta slow since it's a Win factory barrel, 1-9.25/9.5 to the best of my measuring ability.

Laker, what is your load with the 150 BT's?

72 grains of IMR7828 for the 150s

beretzs: I've got a 1/9 on my 7 rem mag and the 180s shoot pretty dang well in that. All that has been over 4000' elevation though.

What's the real difference between the 7 Mashburn and a 300 WM necked down to 284 ( 284 Jarrett ) besides a slightly longer neck on the Mashburn. Does the Mashburn have more powder capacity too ?

Roy I don't really know....never measured the capacity of the 300 WM necked down. The Mashburn has slightly less taper. Six of one/half dozen of the other I think.

I think a lot depends where you seat bullets but we can bet any difference is pretty fractional. Whether he realized it or not,what Jarrett did is reincarnate the Mashurn in a slightly different form. But that's true of a few other 7mm magnums as well.

The mashburn has more panache

The 300/7mm RemMag has almost no taper, and the longer body and shorter neck so a bit more powder capacity. The plain 300WM/7mm is also reffered to as the 7mm Practical.

My 7mm Mashburn marked custom rifle is, I learned when starting to shoot it and inspecting the cases, actually a 7mm Practical. I can run a 300WM case into a 7mm neck sizing dies and have perfect brass. That is one of the things about buying someone else's already built custom, no way to really know the chamber dimensions until shooting it and measureing the fired cases or doing a chamber cast. I am OK with my slightly larger chamber and easier to form cases, and the beautiful engraving of the 7mm Mashburn is so pretty (on a tapered octagon barrel) I am going to leave it as it.

Safariman: "A rose by any other name........"

There ya go!


BTW, anyone have any recipes for 120-140gr bullets in a Mashy or a 7/300? I am still addicted to speed, though have some 140gr Accubombs to try as my higher BC possibility. Cannot wrap my head around barely over 3,000fps for my long range deersmacker, yet.

Thank you. That sounds like a mule deer nightmare!

Unless you limit shots to relatively close, a higher BC bullet started way slower will surpass your impact velocity upon impact.

But it would go against your machoism I know.

Your Mashburn should get a 140 over 3k with it's 26" barrel.

Hell the 7mm-08 can damn near do it with book loads and a 24" barrel.

My .280 A.I. shoots them at 3295 fps from a 24" PacNor 3 groove and a book load.

Buddies 7 RM and a 26" barrel clocks them at 3380 IIRC.

Dober turned me onto the 150s and IMR 7828. He uses them for all that walks. Im planning to run them in my limited entry bull elk this fall unless I decide to carry my kimber Montana in 7mm saum or 6.5mm saum depending on which one I decide to build.

You not interested in the 7mm WSM?

I've always like the 7mm saum. Seems like a 280 ackley in a short action and that to me is a good place to be. Nothing against the wsm just doesn't turn my crank

Stick with the 7's. Hard to find a better place to be.

I was talking about the real heavies of 160 and up.

I was (am) getting 3650 with 120's so figured I should not have to lose down to much lower that 3450-3550, which is still pretty darned fast and those will outrun my 120TTSXS pretty quickly, too.

But as for over 140grs, I still love mega speed bangflops on normal range Mule Deer fairly often, and the longer mid range trajectory. The other limiting factor is this... My beautiful Len Brownell custom rifle has an exquisitely sculpted and fitted checkered STEEL buttplate! Cannot get really pumped up about shooting the heavies with this rifle. And for deer out to 600 max I do not need to. If I need to shoot heavy bullets my 338/8mm RemMAg pushes 225-300gr bullets to some wicked velocities and has a nice, big soft Limbsaver recoil pad

I think that I will start with Dobers 150gr load for my 140's and go from there.

Safariman Id start with 7mm weatherby data and go from there for working up loads in your mashburn with 140s