Hornady Custom 275 Rigby

[MK2750]

Young fellow picked up two boxes of the above 140gr SP. Probably a stupid question but are these 7x57 aka 7mm Mauser under a different name. They certainly appear to be but my 7x57 is a very special rifle built on an older action and I would rather ask a stupid question than make a stupid mistake.

Thanks for any feedback.

 

[vmax204]

Same ammunition 7x57 Mauser = 275 Rigby. The British had to have their own designation for the 7x57, hence the 275 Rigby. Same ammunition.

 

[Potashminer]

I have had both headstamps here - 7x57 and 275 Rigby on Hornady brass - Hornady did some batches like that when Ruger made a run of #1 rifles marked as "275 Rigby" - at least when I went looking for them. I think in old days, Germany and Spain loaded 173 grain or 175 grain as their standard military loading in 7x57 - British company Rigby was only legit importer of German made Mauser actions to Britain - and they marketed a "275 Rigby", maybe some of them as "High Velocity" - I think they used 140 grain bullets, with no other change to the 7x57 round - you most definitely use the same dies for reloading it. Depending on the brand and era of that factory ammo, it may or may not be to modern pressures - should be no more than SAAMI maximum, if it was made in or for USA.

SAAMI was formed in 1920's in USA - so depending on age of your rifle, might have been much older than that. I have a m93 style Mauser in 7x57 that was made in 1896 in Berlin, Germany - so perhaps 30 years before SAAMI existed. I do not know how the original German or Spanish (or Rigby's) breech pressure compared to modern SAAMI standards.

I suspect much old days pressure testing was done using the copper crusher measure - so should be reported as "Copper Units of Pressure - CUP", although some, like US Army, reported that as "Pounds per Square Inch - PSI". Modern pieziometric pressure testing also reports results as "PSI" - so is some room for confusion, if reader does not watch the units that are reported or the testing method that was used - is different process - gets different results - measure in different places in the chamber - but cartridge generating the same "pressure" - just is reported in several different ways, and is tested in different ways. British did altogether different - "tons per square inch" - was really an axial pressure test, not a radial test - challenged the lock up - I do not know how to convert "tons per square inch" to "pounds per square inch" - Long tons? Short tons? Same test place in chamber? Measuring the same thing?

 

[MK2750]

Thanks, all I have read reveals the same. They are claiming 2680 velocity with the 140 grain bullet which is similar to the other common brands. Pressures shouldn't be a problem as the rifle was built on a higher number Springfield 03 action. The 275 Rigby head stamps may have been shipped up here because of ammo shortage or because he purchased them in small town Alberta, they may have been sitting for years.

Hopefully they shoot well. The old rifle was built to shoot 140s but it is a little fussy. It shoots Hornady 7x57 Superformance around an inch, Federal closer to 1 1/2 but the old Remington Core Lotk would often produce a clover leaf group. I have not been able to find that ammo for quite some time.

 

[Potashminer]

If your rifle was made on a 1903 Springfield action in North America, there was never any requirement that the product be "proof tested" by gov't agency like there has been in many European countries - sometimes since centuries ago, over there. Essentially, you are doing the "proof testing" when you fire it. I hope those loads are accurate for you!! My Dad did much hacking on a P17 in 1948 - hacksawing into the chamber area to mount a rear sight, grinding off part of top of front receiver ring to get a better sight picture, and so on - it was never proof tested either - except for the boxes and boxes of shells that he fired through it over the years, after his "ministrations".

 

[MK2750]

Yes, I had it made for my late father 40 some years ago on a 1903 Springfield. It doesn't get out much anymore but has taken deer for 3 generations in my family and who knows how many before that. Hopefully it holds together for a few more.