7mm-300 Win Mag "7MM-WESTER"

[dogz]

My Mashburn on a fall bear hunt.

People try like heck to over think this stuff, the Mashburn came out in the 50's. Page, Hagel, Bowman all used it a lot and spoke highly of it. I've been running one for over 3 decades. I can't imagine a better all purpose close to far round for game from tweety's to elk....

 

[VinceMule]

.350 Length neck, what is not to like?

 

[dogz]

Beauty of the Mash is that it's so darn easy to work with, a bag of 300 WM brass and you're ready to form the brass (takes me 18 minutes to do a bag of 50) and one is ready to fire form. My FF load is so darn good that I can hunt about anything with it. Incredibly accurate and very capable.

64 of 4350 and a 139 Horn flat base, viola ready for the world......

My hunt load has generally been 7828/150 NBT, 175 Noz semi spitzer/R25 and or a 120 TTSX/R22. And from my brothers of the Smashburn fraternity there's a boat load of other combo's that will work!

I love the Big 7's as you can build them light enough to carry and they don't needs brakes or a can. Plus you can shoot a 8 to 8.5 pound rifle "all up" (sling, rounds, scoped) and you can fire them from any angle and not worry about the scoped being driven thru your noggin!!

They're just so darn easy and to date I've not found a round bigger or smaller that will do it any better at the ranges I concern myself with (700 yds or less). If scoped differently I'd have zero issues going to 1K with it. I have an old 4-14 Leo on it with Premier reticle dots out to 700. Dang that was a good company.

 

[Wild Monkey]

The straight necked down version is an excellent round, and once upon a time, there were several members of this forum shooting them, including myself. I actually just chambered another one early last fall but haven't tinkered with it much yet. Most folks figure out that none of the bastardized versions offer enough performance gain to make them worth the extra trouble it takes to form cases. That round you have is a good-looking round, and I'd suspect you're just running the 300 case up into a 7mm Weatherby die. Is that correct?

Correct, It's just a neck down using a 7mm Weatherby sizing die, only you don't go down very far. It's been a few years since I played with it but it was very easy conversion. The Primary reason here is Economy. Seeing 300 Win Mag box ammo and wanting to convert it as is. So lost cases won't be a concern. I had Washburn die made for 300 Win brass but I prefered forming this way./ (The Jarrett does look interesting and I've yet to land one of their Dies for a bargain)

 

[VinceMule]

I hunted coyotes with a guy that had a 25 Mashburn Super, and saw him flip coyotes at 300 yards.

 

[dogz]

I hunted coyotes with a guy that had a 25 Mashburn Super, and saw him flip coyotes at 300 yards.

My kind of yote rifle!

 

[Schw15]

I use to shoot a lit of the 7mm-300 win mag. When I did my reamer I just based it off of the 300 win mag brass neck it down and go shoot. They were some of the easiest calibers to tune. I don't think improving or anything is really needed where it sits is perfect

 

[Wild Monkey]

I use to shoot a lit of the 7mm-300 win mag. When I did my reamer I just based it off of the 300 win mag brass neck it down and go shoot. They were some of the easiest calibers to tune. I don't think improving or anything is really needed where it sits is perfect

Isn't that .235" Neck length? That doesn't seem optimal for a 7mm Bullet?

The 7mm Wby die is readily available yet offers a significantly longer neck than the straight conversion. The Brass flow seems perfect.

 

[Schw15]

I never had one issue. Made mine a custom freebore for the 197 smk and worked fine. Very accurate. That way you can use 300 win mag dies off the shelf put a 7mm bushing in sizer then a 7mm stem in seater and you good. I just figured it was easier and faster.

 

[tjm1534]

I had Kenny build me a 284 Jarrett 15 or so years ago for my Canadian rifle and it's perfect.Fast,accurate and I can use a Kwik Klip to unload whenever you get in the vehicle.

 

[hawg chaser]

I do remember way back in the 70,s they guys who were attempting to build 1000 yard rifles were necking down 300. Weatherby cases to 7mm ! That was the first time I ever heard the term BC !! Apparently in the very early stages of Long Range shooting that was a concept that many thought was an intelligent design ! I think , with the availableity of more precise barrels , it could still be a good idea!! I truly enjoyed reading about the experiments of that time ! Here we are 1/2 a century later ,still tinkering and hitting 10 inch plates 1000 yards away and even 1200 to 1500 yards has become possible ! For me this is still exciting . Reminds me of NASA in the 60,s ! I love this stuff!

A 7-300 WBY was one of the original cartridges that the long range guys around Williamsport, PA used in the 60's.

 

[yobuck]

Back in the very early 50s, Norma introduced a 139 gr 6.5 match grade bullet.
It was introduced to U S shooters at the Camp Perry matches.
Shortly after a 1000 yd target shooter by name of Wright created a reamer using a standard 300 Wby case necked to 6.5 intending to use it for 1000 yd competition.
Word spread to a PA. gunsmith by name of Alex Hoyer of Lewistown PA.
He borrowed the reamer from Wright and commenced to build long range hunting rifles with it.
The cartridge was named 6.5x300 WWH for Wetherby Wright Hoyer.
For a number of years it was the most popular long range cartridge on the planet, and especially in PA.
However, a man by name of Joyce changed all of that when he introduced the Hornady 162 gr 7mm BTHP bullet with a BC of .725 in about 1970.
Hunters were quick to rebarrel their guns for the 7x300 WBY cartridge.
Especially since the 6.5 Norma bullet was illeagle to use in PA for hunting, since its jacket was made of steel.
The 7x300 is as simple as running a standard 300 WBY case thru a 7 mm die and seating the bullet.
Dies did soon become available from RCBS however.
Today in PA that cartridge along with most other of the smaller diameter cartridges has become less popular due the larger ones in 30 cal. and 338.
But the 7x300 WBY is still among the better of the 7mm cartridges.
With 78 gr of 7828 with the 162 gr bullet in my guns having 9 twist barrels, about 3400 fps is achieved with barrels of 27" in length.
A 30" barrel is the same.
So for a hunter, looking for a more potent 7 mm cartridge, dont overlook the 7x300 Weatherby.

 

[6.5x300 WBY]

Back in the very early 50s, Norma introduced a 139 gr 6.5 match grade bullet.
It was introduced to U S shooters at the Camp Perry matches.
Shortly after a 1000 yd target shooter by name of Wright created a reamer using a standard 300 Wby case necked to 6.5 intending to use it for 1000 yd competition.
Word spread to a PA. gunsmith by name of Alex Hoyer of Lewistown PA.
He borrowed the reamer from Wright and commenced to build long range hunting rifles with it.
The cartridge was named 6.5x300 WWH for Wetherby Wright Hoyer.
For a number of years it was the most popular long range cartridge on the planet, and especially in PA.
However, a man by name of Joyce changed all of that when he introduced the Hornady 162 gr 7mm BTHP bullet with a BC of .725 in about 1970.
Hunters were quick to rebarrel their guns for the 7x300 WBY cartridge.
Especially since the 6.5 Norma bullet was illeagle to use in PA for hunting, since its jacket was made of steel.
The 7x300 is as simple as running a standard 300 WBY case thru a 7 mm die and seating the bullet.
Dies did soon become available from RCBS however.
Today in PA that cartridge along with most other of the smaller diameter cartridges has become less popular due the larger ones in 30 cal. and 338.
But the 7x300 WBY is still among the better of the 7mm cartridges.
With 78 gr of 7828 with the 162 gr bullet in my guns having 9 twist barrels, about 3400 fps is achieved with barrels of 27" in length.
A 30" barrel is the same.
So for a hunter, looking for a more potent 7 mm cartridge, dont overlook the 7x300 Weatherby.

Love all these big 7's. But decisions.
What way to go.
28NOZ
7RUM
7x300bee
7mmLRM= McWhorter's version of 300 prc necked down to 7mm.
Decisions Decisions Decisions

 

[Tikka300man]

Rummaging through the Pink Vault basement again.... I always had the desire for a 7mm-300 Win Mag. Most Shooters who build a straight neck-down version don't speak highly of it (for whatever reason). This version has a slightly longer neck. It utilizes the Weatherby double-radius design. Zero donuts are apparent. The Weatherby design forms the brass beautifully and makes it a natural creation. I have a Rem Mag barrel if I ever find a gunsmith willing to chamber it. "7mm-300 Weather-Chester" or "7-300 Wby-Win"? "7mm-Wester" it is. The photo shows 162 ELDX.

In all honesty they make a wildcat similar to this (w/o the double radius shoulder), it's called the 7mm Practical and it has had quite a bit of development put into it, so all of bugs have been worked out. Couldn't hurt to check it out as I know reamers are made for it. Just a thought

Rummaging through the Pink Vault basement again.... I always had the desire for a 7mm-300 Win Mag. Most Shooters who build a straight neck-down version don't speak highly of it (for whatever reason). This version has a slightly longer neck. It utilizes the Weatherby double-radius design. Zero donuts are apparent. The Weatherby design forms the brass beautifully and makes it a natural creation. I have a Rem Mag barrel if I ever find a gunsmith willing to chamber it. "7mm-300 Weather-Chester" or "7-300 Wby-Win"? "7mm-Wester" it is. The photo shows 162 ELDX.

If you don't require the double radius shoulder then they already make a tried and true version of the 7mm-300 Win Mag, it's called the 7mm Practical. Gunsmiths might have a reamer for it.