More data.
Here's Jack O'Connor describing his 7x57 Mauser Sukalle-Minar:
http://www.gundigest.com/ammunition-reviews-articles/forty-years-little-7mmI got my first 757 rifle in 1934. I saw it at Bill Sukalles shop in Tucson. Bill had put a 757 barrel on a remodeled action from a World War I German Model 98 Mauser snipers rifle. It had been magnificently stocked in handsome French walnut by Adolph G. Minar of Fountain, Colorado, one of the finest classic stackers [sic] that ever lived. The stock had a German trap buttplate and a trap grip cap. It had as iron sights a Lyman 1-A peep on the cocking piece and a ramp front sight with gold bead. With iron sights, the rifle weighed slightly less than 7 pounds. However, it was equipped with a big German Gerard scope on claw mounts, which outfit added about two pounds. The scope was good optically, but because of the soft mount, it would not hold a constant point of impact. I traded the scope off. However, the rifle with iron sights was an astounding bargain at $75. Thats right-$75! I took off the Lyman 1-A and had a 4x Noske scope put on with the Noske mount. The outfit then weighed less than 8 pounds.
The 757 is loaded all over the world. Here is some of the good RWS (German) ammo.
I shot my first desert ram with that rifle, one of the best Rocky Mountain mule deer I have ever knocked off, and various other game all with the Western factory 139-gr. open point bullet load. With one exception, everything I shot at with a 757 was a one-shot kill. That was a desert mule deer which I shot in one ham as he ran directly away and on which I used two cartridges. Then about 1952, I caught up. Hunting on Idahos Snake River with another 757, I picked out a nice fat doe and took a crack at her. Down the hill she rolled and also a forkhorn buck that had been standing behind her.
Sadly enough, I traded off that lovely little Sukalle-Minar 757, along about 1940, for an equally handsome 2-R Lovell on a Sharps-Borchardt action. Like the 757, it had been barreled by Sukalle and stocked by Minar.So, his was a Mauser action with a Lyman cocking piece sight. The one on Gun Broker is a Springfield action with regular Lyman aperture sight.
But the two rifles are extremely similar. The must have been built very close together in time. They both have the same furniture otherwise, and the Gun Broker rifle has a written description apparently by Jack O'Connor, giving it some kind of mysterious connection to O'Connor.
