Ladder Tests In A Modern 7x57 Action

While the original 7X57 Mauser was based upon a 175gr round nosed bullet, later spitzer (spire) bullets were used.

Possibly the longer throat was kept to help keep pressures in check.

 

I was focused on action diameter and strengths, and forgot about that bolt shroud. I’ve always suspected it was a big part of the reason Elmer migrated away from both the ‘03 Springfield and even the Model 70 Winchester. That, plus the better gas venting on the 98 bolt, allowing it to dump into the magazine and not confine it to the firing pin raceway. IIRC, Germany continued to use mild alloy steel like 1035 up through WWII, differentially hardened. Gave them an action that would stretch with way high pressures, not explode. Again, IIRC (my references are still in boxes, having just moved) Brno’s VZ24, VZ33, and FNs 98s of various patterns had started being produced from steel such as 4140 chrome moly by 1930s. I would bet the German produced 93s and 95s were mild steel, differentially hardened. The 96s were made of Swedish steels, even when made by Oberndorf, as was specified in the contract. Again, IIRC. Makes me nervous to not have easy access to the sources, so double check my info by doing a bit of searching on the net.

I do agree an 7x57AI on an ‘06 length action would be fun to play with. Ought to come pretty much even with the .280 Rem. But with the long action, it makes way more sense to just go to the .280 to start with an avoid the additional costs of playing with ‘cats.

 

Maybe, but I suspect it was more that the new ammo shot well enough in the old chamber so there wasn't much incentive to change. There was a disincentive too in that the older ammo form often continued in use for a surprisingly long time after the change, relegated to practice - or maybe military authorities were less efficient than we might think about where they stored ammo and how they recorded it, so old stock kept turning up long after it should have been used. Either way, keeping the RN bullet throat was a plus.

There are some exceptions. US .30-03 to .30-06, but that also saw the case neck length reduced, and the German adoption of the 198gn sS FMJBT version of the 7.92X57is in rifles. The leade / throat saw a lot of changes, but as I understand it that was to allow what was a high-pressure machine gun loading to be adopted as the sole ball cartridge form for logistics reasons. This hot ammo risked over high pressures in the standard 'is' rifle chamber.

 

By the start of WWI, pretty much everybody had switched to spitzer bullets in 7x57, 7.65x53, 8x57, 30-06, .303 Brit, etc. The ball seat/throat would be easier to change by just swapping out reamers, so retaining a long throat probably was not done to facilitate RN ball ammo, but for some other reason. I recall seeing a number of years ago a translation (copy) of a Brazilian order for 7mm ammo from FN in the early 1930s. Basically was a 160 gr boattail spitzer of .286” diameter at something over 2600fps. I have been told that the European practice when rifling military firearms was to have deep grooves to prolong useful barrel life. I have 2 VZ24 in 7mm; both have grooves of .287”; a 1908 Brazilian infantry rifle made by Mauser, not DWM, has grooves at .2854; an Oberndorf commercial from the late 1930s is about .286. They all shot pretty well with 140gr .284 Nosler partitions.

I’m not well versed on throating changes with 7.92 military Mausers, but do know that Mauser (and likely other continental makers) changed the throating on their .318 groove version of the 8x57, so that the .323 diameter bulleted ammo could be safely fired in them.