Beibs sent me a few empties Marked Kynoch .275 Magnum several months ago and I'm warming up to the nostalgia of this belted round that was developed by Holland and Holland around 1912. So..., any .275 H&H magnum fans out there? Thanks. CB

Just a thought on this old cartridge

The barrel and bullet dimension is not a true 7mm ( .284 cal)

The 275 Magnum uses a 7.3mm (.278 inch ) bullet this might be a problem unless one is to build it with a "American " 7 mm barrel ( but then it would pose problems using 275 H&H dies.

Woodleigh does make specific sized bullets for this caliber

It is akin to the 6.5mm Carcano which is not a 6.5 but actually a 6.8mm ( .268 inch)

ALF. I noticed a difference in the bullet diameter as well. But, I thought it was .287. Not?

quote:

Originally posted by custombolt:
Beibs sent me a few empties Marked Kynoch .275 Magnum several months ago and I'm warming up to the nostalgia of this belted round that was developed by Holland and Holland around 1912. So..., any .275 H&H magnum fans out there? Thanks. CB

Well, yes and no. I use a .276 Dubiel which is the same case, but different shoulder angle and .284 bore.

Darn nice cartridge.

I toyed with doing a .275 mag using .284 bullets. I have a .280 Dubiel made for .284 bullets rather than original .287, dies work fine(full length .300 H&H necked down) The two get mixed up by some people

I am sure the 7mm Sharpe and Hart was patterned after the .275 Mag, as well.

The .275 mag sure seemed to die rather quickly even though there is still some new brass offered. Some say the .270 may have bumped it off it's throne if it ever had one. From what I've gathered so far I think the powder choices of the day limited it's performance. Still, It seems to have potential with modern smokeless powders and I'd go with .284 diameter bullets as well.

Like most of the cartridges developed in England, the 275 magnum struggled to compete with cartridges around the rest of the world due to the 'odd' sized bullet and underloaded cartridge (possibly due to lack of suitable powders back then) not helping the cause.

The American developed and Norma produced 7x61 S&H was of a similar size to the 275 Magnum but used standard 7mm (.284") bullets, was loaded right up with the wildcat 7mm magnums that were around at the time of its development with the classic 160gr SPBT bullet at 3100fps. Reloading dies were readily available, produced as standard by at least Lyman and maybe others.

This cartridge was popular around the world even to some extent in the States until Remington came out with their 7mm Magnum. Even Joyce Hornady used a 7x61 to take a record book moose at one stage. The only factory rifle made for the 7x61 S&H was the Danish Schultz and Larsen, a fantastically accurate platform for the 7mm cartridge but of course this limited the growth of the cartridge and allowed the Remington version to become one of the most popular magnums ever produced.

The 275 magnum should be able to be loaded up with a 160gr bullet to close to 3000fps with the powders now available.

Thank you. Very interesting. I'm still wondering what they were thinking with that odd bullet size. What it could have been.

Sorry for the mistake: the 275 H&H is a .287 Bullet (7.3mm)

The history of this cartridge is interesting.

The impact and reach of Mauser's influence on our modern shooting world is profound and often overlooked and dismissed by many shooters.

The impact of Mauser's M93 7x57 was huge !


In the US it ultimately led to the development of the 30-06 at the hand of the tremendous losses suffered at the battle of San Juan Hill and in the UK it led to a extensive experimental development of their own 7mm cal cartridge also because of their dealings with Mauser during the Boer war.

The 7.3mm cal .275 H&H was likely a direct result of the "sting" of the little Mauser.

The original 7x57 was not a .284, 7mm but shot a 7.25mm (.285) bullet.

This was not by chance !

Experiments at the time led to the choosing of this caliber bullet because of mainly accuracy and problems with fouling with smaller caliber 7mm's


The 276 Enfield went through extensive caliber R&D going from a smaller 5.68mm bullet, then a 7.2mm bullet to the larger 7.3 mm bullet.

Because these were military cartridges often shot form very hot chambers due to multiple repetitive shooting cook off's occurred ! Original reports in the R&D of the 276 show this.

At the same time FW Jones of Eley developed the 280 Ross aka 7x66 Rs for Charles Ross of Canada. The cartridge was great, the rifle sucked !

This was also not a 7mm but a 7.3mm

FW Jones Developed the 275 H&H for H&H by basically adding a H&H belt to the 280. thus then the 275 H&H with its 7.3mm bullet.

The 280 was a screamer ! Gerligh and Halbe two German gunmakers took the Ross, loaded it with German flake and a 100 gr bullet /The named it the 280 Halger / shot it from their 28 inch barrel "Halger Mauser" and clocked 3900 fps. This was shot and confirmed at the Hallensee Proving ground in Berlin on 21 December 1926 The shooter was one Mr Vigilant-Itinerant. This guy shot a 10mm 5 shot group with this rifle using a German "Ajax" Scope