Q: I bought a Browning Model 71 from a friend who was scared of the recoil. He’d had it re-chambered to the .348 Ackley Improved.
Now I need data for 200gn and 250gn bullets. Do you know of anywhere I can find this information?
Dudley Fisher
A: The .348 Winchester was designed for the Winchester Model 71, a beefed-up version of the old Model 1886, and was intended to be more powerful than the .33 WCF. The Browning Model 71 was a nicely made copy of the original.
Ackley’s Handbook Volume 1 lists data for the .348 Improved. According to Ackley, the original .348 cartridge was poorly designed and had too steep a body taper, which increased back-thrust on the bolt to more than it should have been, particularly in lever actions.
The ‘improved’ version combined minimum body taper with a sharp shoulder and gave a noticeable increase in velocity over the factory round.
The data in Ackley’s book was developed by Robert Hutton of Guns & Ammo magazine and should be more reliable than some of the other data in Ackley’s book.
Loads with 200 and 250gn bullets all use IMR 4350, but you should be able to safely substitute AR2209.
Loads with the 200gn bullet list 68gn as doing 771m/s (2530fps) up to a maximum 71gn for 826m/s (2710fps).
With the 250gn bullet, 62gn of 4350 gets 725m/s (2380fps) up to 66gn for 771m/s (2530fps).
Personally, I think you should begin load development for the .348 Improved using starting loads published for the standard .348 Winchester in the eighth edition of the Hornady handbook and carefully work up to maximum for your particular rifle.
Cast bullet loads for the .348 Winchester (187gn and 255gn) are listed in Lyman’s Cast Bullet Handbook.
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