Weatherby’s Sensational 270 Magnum Part 2

The 270 Weatherby Magnum is like no other 270. It is faster, farther reaching and harder hitting than any other in production 270 cartridge as presented in Part 1. The 270 Weatherby is suitable for hunting everything from coyote to moose and able to close the distance between hunter and quarry like few other big game cartridges. Pictured L-R 270 Weatherby, 270 Winchester and .270 Winchester Short Magnum.

The Weatherby Euromark was shot with factory ammo and handloads. New brass was Norma brand, the same used for factory ammunition. On a Vickers hardness scale Norma brass is annealed to 120 Hv at the neck and shoulders, soft enough to chamber seal, but with enough springback to maintain neck tension for at least ten years. The case body hardness increases to 170 Kv to assure chamber conformance under pressure, but with minimized stretch and no splitting. The case head and primer pockets are hardened to 190 Hv where less yield and more strength is required.

Norma brass is bright yellow, missing some of the red case seen on other companies’ cartridge cases. This reflects a slight reduction in in copper content and proportional increase in zinc. The change makes the material more malleable and ductile so it can be blown out under chamber pressure to conform without changing its properties or losing its strength. I’ve found Norma brass, under any brand name, to be the longest lived when handloading.

Personality

Note – My apologies for the changes in color and illumination in photos. We’ve been working between two cameras, lighting set ups and color temperature changes and it all ended up looking bad. When we get through this we’ll start from scratch and reset everything.

The 270 Weatherby Magnum, while based on the belted 375 H&H case, is one of the three shortened 2.495″ case length Weatherby magnums; 257 Weatherby, 270 Weatherby and 7mm Weatherby. Case capacity varies a couple of grains based on bullet diameter, but all are near the 270 Weatherby’s 82 grain capacity.

 

As an overbore capacity case, they do tend to wear barrel faster than a more mundane 270 Winchester. The Real Guns Barrel Burner Calculator assigns a relative Barrel Burner index of 18.9. By comparison, the .270 Winchester rates a 15.7 and the 270 WSM, a 18.4. What does that infer? If you run 100 rounds of ammo through your 270 Weatherby each year, the barrel last approximately 30 years providing excellent hunting accuracy version 40 years for the 270 Winchester.

 

The 270 Weatherby is an easy to handload cartridge, the Weatherby action handles the cartridge length with ease, the long neck lends itself to flexible bullet seating. The smallish bore needs a longer barrel for adequate bore volume to burn all of that powder, so the 26″ barrel on the Mark V Euromark is put to good use.

 

There are lots of 0.277″ bullets out there for target practice, for larger varmints, for thin skinned deer and for heavier elk and moose. Bullet weight runs from 90 grains to 180 grains. One of the benefits of the 270 Weatherby being a performance upgrade of an original factory hotrod is that bullet designed impact velocity to assure proper expansion falls into the 1900 to 3000 fps range, which makes virtually any bullet designed for the 270 Winchester or 270 WSM work well with the 270 Weatherby magnum.

 

Four common bullets were selected for handloads. They pretty much cover the range from varmint to big game and they have a proven track record.

 

 

There is a Woodleigh 180 grain bullet with a BC of 0.513. It has a 2,800 fps, plus a bit, potential with nearly 3,200 ft-lbs of energy. It’s a long bullet, but the Weatherby’s 10″ twist should be tight enough to provide stabilization and this is where all of that extra case capacity comes in handy with an approximate 250 fps edge over the 270 Winchester. Unfortunately, we couldn’t get any in before deadline. Next time.

Handloads

Forster Benchrest dies were used to assemble handloads, mostly because I wanted an opportunity to work with them. Considering the relatively high price tag, I have to say I wasn’t excited about the quality of their fit and finish. Assembled ammunition was no more concentric or dimensionally consistent than ammunition assembled with RCBS or Hornady dies at nearly half the price, and not as good as ammunition assembled with standard or competition Redding dies.

 

 

Mark V Weatherby rifles chambered for the 270 Weatherby have a throat length of 0.378″ compared to a 270 Winchester with an 0.300″ spec throat. The difference seems not to be of consequence in regard to accuracy, but it does service its primary purpose well, which is to reduce start pressure.

 

 

There are a good number of powder types that work well with the 270 Weatherby cartridge. Faster burning powder in concert with lighter weight bullets was investigated in an effort to cut muzzle pressure, however, it seemed everything fell into the 15,000 psi to 17,000 psi range. Subsequently, we went with a case full approach instead.

 

I am not sure why I keep trying to get H4831 to work with overbore cartridges. perhaps because it is often recommended for those applications. Unfortunately, it always seems to turn in disappointing velocity even when it has reached a pressure limit.

 

Re25 was too slow for this cartridge. It did not deliver good velocity and a full grain difference yielded only a 9 fps difference in velocity with a good chunk of unburned powder passing beyond the muzzle of the 26″ barrel. Norma MRP worked very well in terms of accuracy and velocity. Norma 217 proved to be a bit too slow, not unlike Re25.

Warning: Bullet selections are specific, and loads are not valid with substitutions of different bullets of the same weight. Variations in bullet length will alter net case capacity, pressure and velocity. Primer selection is specific and primer types are not interchangeable. These are maximum loads in my firearms and may be excessive in others. All loads should be reduced by 5% as a starting point for development where cartridges have greater than 40 grains in capacity and 10% for cartridges with less than 40 grain capacity following safe handloading practices as represented in established mainstream reloading manuals. Presentation of these loads does not constitute a solicitation for their use, nor a recommendation.

 

 

 

Overall

The Weatherby Mark V Euromark is, in no uncertain terms, a beautiful rifle… which may leave some shooters unprepared  for what happens when the trigger is pulled. Recoil is not bad. The rifle has enough heft to take the recoil down to a level that the Decelerator recoil pad can make reasonable for most shooters. The 270 Weatherby does put out some muzzle blast and I would not describe its report as moderate. It is what it is… which is a flat shooting, big game hunting rifle.

The rifle was tight and fit and finish were excellent as received. They remained so when the shooting was over.  Accuracy was very good and it could be improved upon with a bit more handload development. It is unfortunate that every gun forum has every rifle and every shooter delivering half MOA group sizes as this flies in the face of reality. That said, a rifle delivering this sort of accuracy could down game at 500 yards for any a shooter up to the task. I want one. It is just way too nice of a combination to pass up. Now all I have to do is start saving my pennies.

Weatherby’s Sensational 270 Magnum Part 1
Weatherby’s Sensational 270 Magnum Part 2