Rolling Block M1897 7MM ammunition

[Uncle]

What type of slug was used in the original issue 7x57 Spanish Mauser round? Was it a round nosed or pointed nose bullet? Does anyone have any suggestions as to what type of round I should shoot in my rifle? Would the modern 173 grain mauser rounds be workable?

[tjack]

The early 7mm Mauser military ammunition used a 173 gr full metal jacket bullet at about 2,296 FPS. I've used bullets anywhere from 139gr to 175gr. They all seem to shoot reasonably well considering that the rolling blocks in 7mm usually have pretty worn bores. You can run into a problem with new, commercial ammo. When the specs for the cartridge were standardized in the '20's or '30's a slightly shorter case (from the base to the start of the shoulder) was used creating a head space problem for the rolling block. The simplest way to fix this is to run your new cases thru a .30 caliber expander plug (I have an M1 Garand so I use a .30-06 sizer die). Then, using one case, run it up into a 7mm Mauser sizing die only a very short distance. You want to neck down the case in small increments. Check to see if the case will chamber. Keep turning down the size die in small amounts until the case will chamber, the block will close and the hammer can be let down all the way. If you can feel the hammer sliding under the block with slight pressure you have taken up all the head space. Lock down your sizer die and finish the rest of your cases. They are ready for loading after removing sizing lube. Use the LOWEST recommended powder charge for the bullet you are using. The rolling block is a strong action but it will flex under high pressure "bending" cases slightly. I bought my 1st 7mm rolling block in the early 1970's and have several now. The ONLY case failures I have had is with necks that split. The rolling blocks have pretty eroded leads from years of use with corrosive ammo so the case neck expands pretty good when firing. When reloading I neck size the case only as far down as I seat the bullet. I also anneal cases after every 2nd firing.