Updated 7x61 Super Data
Date: Apr 06 2015
There is a fair amount of published load data available for the 7x61, though it’s virtually all quite dated. Norma increased the powder capacity of the original case during the 1960s and subsequently renamed it the 7x61 Super, but most shooters continue to refer to this magnum as the 7x61 Sharpe & Hart.
For this handloading endeavor, a NULA Model 28 7x61 with a 26-inch No. 3 contour Douglas stainless barrel (one-in-10-inch twist) was used. The rifle weighs 6.2 pounds. A Leupold VX-3 2.5- 8x 36mm scope in Talley lightweight rings added exactly one more pound.
From a handloader’s perspective, there are some important cautionary points regarding the 7x61 that are not generally applicable to “commercial” rounds. It appears that most, perhaps all, Schultz & Larsen rifles had factory freebored throats. With regard to custom rifles in 7x61, some may have freebore, while others, like the NULA, do not. There is a review of a Schultz & Larsen Model 60 in the December 1957 American Rifleman that mentions a 1⁄4-inch freebore. So does an old Lyman manual (No. 44) from 1967 in a description of its Schultz & Larsen Model 65DL test rifle. Lyman recommended reducing loads 5 percent for non-freebored guns. Ken Waters also covered the matter in his 1974 7x61 “Pet Loads” article (Handloader No. 47). Regardless of a 7x61 rifle’s origin, throat type should be determined before working up handloads.
Depending on the source, specifications for case dimensions, namely overall length and neck diameter, also vary. A chamber cast should be in order for anyone with doubts about the dimensions of a chamber, particularly if the rifle is anything other than an original Schultz & Larsen. Published figures on maximum allowable neck diameters differ considerably. The Norma factory ammunition I have (circa 1970s) has an outside diameter averaging .3138 inch. After firing in the NULA, the neck diameter measures .319 inch. Maximum overall cartridge length may be listed anywhere between 2.394 to 2.402 inches, the latter most common. This is the figure Ken Waters used in his 1974 article. Published shoulder angles also vary from 37 to 44 degrees, but most sources list it at 44. Ken Waters called it 43 degrees, 12 minutes.
Another caveat is the redesign of the 7x61 Sharpe & Hart case. Outside dimensions, of course, remained the same. Internally, the web and case walls were thinned somewhat to increase powder capacity. The newer case became the Norma 7x61 Super. Such cases (recent production from Norma) were used for the data in this article. Water capacity is 76 grains. Original 7x61 brass has a water capacity of approximately 71 grains. By comparison, the 7mm Remington Magnum case averages around 81.6 grains. Early 7x61 brass is probably still out there and being loaded, old as it may be. The matter is further compounded by a myriad of 7x61 brass that has been reformed from other magnum cases. As a result, there are significant variances in powder capacities. In light of all this, handloaders should treat the 7x61 with the extra caution reserved for wildcat cartridges.
I discovered a couple of characteristic features of NULA rifles when I worked with my first one several years ago. First, forget spent primer appearance as an indication of high pressure. This once favored method of judging pressure has been proven to be less than reliable on several counts. The same can be said for measuring case head expansion and pressure ring expansion. In a NULA .308 Winchester that has had well more than 1,000 handloaded rounds fired in it, I have yet to observe anything resembling a flattened primer. The 7x61 responds like the .308 in this regard – spent primers all look the same despite varying charges of different powders.
Secondly, what about heavy bolt lift as an indication of high pressure? This is usually a sign of excessive pressure, in fact, probably pressure well beyond excessive. Melvin Forbes reiterated by stating that heavy bolt lift will normally be the first high-pressure symptom in one of his rifles. However, it’s important to note that everything fits closely in a NULA action. Bolt closing and bolt lift require a little more exertion, whether there is a cartridge in the chamber or not, than most mass-produced, bolt-action rifles, but one quickly develops a feeling for the slight extra effort required.
These cautionary points are emphasized, as it was necessary to develop new 7x61 loads using components that were not available almost 40 years ago when Ken Waters did the Handloader article. A variety of checks were used to ensure that all data was safe in the test rifle. With normal judicious handloading procedures that included taking into account the previously mentioned factors regarding the 7x61, loads in the data table appeared to be safe in the test rifle.