7 mm magnum

G

g n brezinski

Member
i was looking throught some emails of mine and found one on the 7 mm magnum of bobby harts design with the 40 degree shoulder.my ? is the email sated that a 150 grain bullet can go about 3400 fps out of a 26 hart 1/9 barrel of harts.what I see is it that is the case is a ackly type and it is said to gain about 3to5 grains of powder.any thought on this.
gary b
 
Read & Heed literature from a couple reloading manuals to compare a 7mm Rem Mag a 7mmWtby Mag & a 7mm STW by comparison.
The Ackley Improved variation will fall between the 7 Rem Mag & 7 Wtby Mag.
The shorter of the 3 listed chamberings, the 7 Rem Mag chambering,if accomplished correctly should not be reamed to AI w/o setting the barrel back & rechambering.
 
Not the first but perhaps the first successful

7mm Mag was the 7x61 Sharpe & Hart. It preceded the Rem 7mm Mag by about 10 years. It lost to the Rem because there was basically only one rifle chambered for it in quantity, the Schultz and Larsen, although Browning and Sako reportedly did a few, limited sourcing of ammo (Norma) and components. Its advantage was it used a standard length action. Its a superb design.
 
I suppose 3400 fps with a 150 gr. bullet is possible in an improved case. However, there have been many claims over the years, particularly with wildcat cartridges, of increased velocities that result not only because of a slight increase in powder capacity but an increase in chamber pressure, perhaps greater than it safely should be. We seldom know for sure because there are no SAAMI specs or pressure tests performed.

As for the 7x61 Sharpe & Hart Magnum and 7mm Remington Magnum...After fifty+ years of handloading many rifle cartridges (including wildcats and "improved" versions), I recently bought my first 7mm Remington Magnum, a 700 Sendero with 26" barrel. I had fairly extensive experience with the 7x61 in an original Schultz & Larsen Model 60 and a New Ultra Light Arms M28 (26" barrel)that will soon be sent back for its third barrel. I always though the 7mm Remington had a measureable ballistic advantage over the 7x61 because the water case capacity of the Remington cartridge was around 5-6 grains greater than the Sharpe & Hart.

Recent load development and chronograph results indicate the two cartridges are pretty much ballistic equals, though the 7x61(in the NULA rifle) is a bit more efficient in that it uses slightly less powder in most instances. The Schultz & Larsen has a factory freebored barrel and it requires 2-3 grains more powder to achieve the same velocity as the NULA.
 
Norma

tried to bring the 7x61 S&H closer to 7mm RM ballistics by changing the wall thickness of the brass and thereby increasing internal capacity, which was when the headstand changed from 7x61 S&H to Super 7x61. The big advantage, other than efficiency you point out, is the ability to use a std. 30-06 length action. The other big contributor to muzzle velocity in large capacity cases is barrel length. One has to look at this carefully when comparing rifles of like or similar chambering.

Remember when Winchester introduced the 264 Win Mag...the westerner had a 26" barrel in order to allow all that powder to burn and contribute to specified muzzle velocity. When they came out with the M70 Featherweight they did so, for a while, in 264 with a 22" barrel. Not only did MV suffer but the rifle turned into a fire breathing dragon...it really depressed appetite for the cartridge. Put that case in a rifle with the proper length barrel and it shines as a long range rifle. Like a lot of things in the firearm arena, there are certain case designs that are head and shoulders above other similar designs, but many that are kissing cousins. The 7x61 and Rem 7mm Mag are two of the latter imo.

I love my Schultz and Larsen. Mine is the first iteration...54J. Some don't like the cock on closing and the rear lugs, but I have never minded these features. I've shot enough 1917 Enfields and Lee Enfields to be comfortable with the cock on closing feature. Regarding the rear locking lugs, Frank McKee, arguably one of the best Hunter rifle shooter in recent memory shot Rem 781s, hot, a lot with no brass issues. The S&Ls are prolly one of the best semi-custom used rifle buys around imo, next to the Browning/FN Safari, Medallion and Olympian bolt guns, provided you scan them for salt wood.
 
The cock-on-closing feature of the S&L action is probably undesirable only to those who have had little or no experience with it. It takes little effort and one quickly becomes used to it. As for Norma's effort to better market the cartridge by developing the "Super" case around '68, the ploy was probably ten years too late. A Norma executive mentioned several years ago that manufacturing loaded ammo again would be very easy to do if there was a demand. I suppose that's unlikely, but the 7x61 remains a fine cartridge without the boring look of Remington's magnum ....
 
Well

at least we owners can get new Norma brass for the super 7x61. Sharpe and Hartt figured out a pretty good design(working off a European case I believe), convinced Norma to produce cases and reamers, so it was always a bit of an uphill battle to get the limited number of rifles offered shooting. Remington won the battle with lots of rifles and loaded ammo. Its a good lesson for others to learn from.
 
To give some idea as to demand for the brass, I spoke with the Norma rep. several years ago and he said they were expecting a shipment from the factory in the coming month or two. He said there were 4,000 cases in the batch. I don't know whether that was one batch for the entire year or several were shipped annually. Regardless, one shipment to the USA containing 4,000 pieces is a pretty small order.
 
Yes 4000 cases

is a small order. Perhaps Norma is not run by bean counters and Wharton School grads?
 
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