7x57 R

[Sjs52]

Hi, I just joined the forum.
I purchased a Merkel 7x57 R and decided to learn to reload being this caliber seems to like reloads.
If anyone has reloaded the 7x57 R, where did you go for the reloading data. Lyman book doesn't have info on the rimmed version.
Thanks for any input provided.

 

[liltank]

Here's a good place to start:
http://reloadersnest.com/frontpage.asp?CaliberID=221

 

[Laurie]

The 7X57R is ballistically identical to the rimless version so any given bullet + powder combination gives the same results subject to the usual sorts of variations that affect any cartridge design, primarily make and thickness / capacity of the case and the chamber dimensions on the individual rifle the cartridge is fired in.

HOWEVER ..... as is the norm with European cartridges that have rimmed and rimless versions, the former being designed for weaker drillings and break-open action rifles, they are specified with a lower MAP (Maximum Average Pressure) rating. CIP, the European equivalent of the US SAAMI body specifies an MAP of 390 MPa / 56,550 psi for the rimless 7X57 and 340 MPa / 49,300 psi for the rimmed 7X57R.

So, what works well in the 7X57 and the widely available loading data is simply used but with a lower maximum charge. How much lower?

Here are Vihtavuori's starting / maximum loads for the pair

120gn Sierra Spitzer ........ 7X57R 41.9-45.8gn N140 ................... 7X57 43.5-47.2gn N140
.......................................... 7X57R 42.3-46.3gn N150 ................... 7X57 44.0-47.6gn N150


140gn Nosler Ball Tip ........ 7X57R 38.1-42.2gn N140 .................... 7X57 39.7-43.5gn N140
.......................................... 7X57R 39.0-43.4gn N150 .................... 7X57 40.9-44.8gn N150

160gn Sierra SBT .............. 7X57R 36.8-41.0gn N150 ..................... 7X57 38.6-42.7gn N150
.......................................... 7X57R 45.2-49.3gn N160 ..................... 7X57 47.0-50.3gn N160

You can see the pattern. Recommended 7X57 maximum loads are reduced by 1 to 2gn, most in the 1.3/1.5gn area. Looking at the European Lovex powders loading guide (European powder manufacturers normally include the rimmed versions of various cartridges alongside the rimless due to the continuing use of 'drillings'), the same pattern appears.

For instance, the maximum load for Lovex SO65 (a powder somewhere between VarGet and the 4350 in its behaviours) and the slowest burning rate version shown for for the 175gn Nosler Partition bullet is 42.4gn for the 7X57R; 44.0gn for the 7X57mm.

So, look up the plentiful data for 7X57mm, choose a suitable looking combination, reduce the maximum charge by 2.0gn and reduce that by 7.5-10% to get a starting charge before working up in 0.4gn steps. You'll manage fine doing that.

Generally speaking the 7X57 likes powders with burning rates similar to IMR/H4350-4831, Viht N150-N160 for 150gn and heavier bullets. In your shoes, I'd also go onto the Hodgdon website, access the Reloading Data Center online loads facility and specify 7X57mm. There are loads there for every suitable IMR and Hodgdon powder for bullets ranging from 100-175gn. Again, simply reduce the maximum loads by a couple of grains.

 

[normmatzen]

Laurie raises a very good point in mentioning the CIP loadings for the 7X57 loadings.

The SAMMI limits for pressure in the 7X57 is the basis for most US loading manuals and are somewhat lighter than CIP based manuals.

This difference seems to be lawyer induced on the theory that old Small ring Mausers are inherently weak. That is open to discussion, but if you are using a strong action in good shape, the CIP limits are more reasonable.

 

[Sjs52]

Thanks for the info. I am meeting with a fellow today and he is going to start me on the path. He has been reloading for a good 25 + years and hasn't done much in the last few due to work. He is pretty excited that someone is interested and hopes to reignite his passion of yesteyear.