A few months ago I had a gunsmith rebarrel my .378 weatherby magnum with a 28" Shilen barrel. I have been seeing slight injector marks on my reloads so I backed off my loads 10% below max and started over. And today I bought some factory ammo and the injector mark showed up on the factory ammo. The primers all look good and there is no sticky bolt lift. Also I loaded 114 grains of H-4831 with a 270 grain TSX, Fed 215 primer and the rifle shot a 3/4" group @ 100 yards (3-Shots. I had the gunsmith take a look at the brass and he thought everything was ok. Plus I had a gentlemen (gun builder) look at the brass and he also stated everything looked good, but noticed that the primers were showing a slight flattness to them. The only thing I can thing to do is shot the reduced loads thru my chronogragh any go from there. Any suggestion

THANKS

Steve

Steve,
I think what has happened is your gunsmith used a standard chamber reamer. Weatherby uses a lot of “free bore†in their rifles. This reduces pressure. When you rebarrel and don’t have the “free bore†you will get more pressure with a given round also with factory ammo that is loaded to be shot in rifles with “free boreâ€. You may need to reduce loads slightly in this rifle.
Bill

Bill

I forgot to mention the barrel has .760" of freebore.

Steve

My factory stock (- bedding and trigger) MK V 270 wby does the same thing with factory ammo, But my bolt lift and extraction are always 100% normal. How hot was it when you where shooting? How hot was the gun? I'd email wby and see what they say cause' I know they load there ammo hot. I just never worried about it because I handload.

Jake

quote:

Originally posted by Steve Lefforge:
A few months ago I had a gunsmith rebarrel my .378 weatherby magnum with a 28" Shilen barrel. I have been seeing slight injector marks on my reloads so I backed off my loads 10% below max and started over. And today I bought some factory ammo and the injector mark showed up on the factory ammo. The primers all look good and there is no sticky bolt lift. Also I loaded 114 grains of H-4831 with a 270 grain TSX, Fed 215 primer and the rifle shot a 3/4" group @ 100 yards (3-Shots. I had the gunsmith take a look at the brass and he thought everything was ok. Plus I had a gentlemen (gun builder) look at the brass and he also stated everything looked good, but noticed that the primers were showing a slight flattness to them. The only thing I can thing to do is shot the reduced loads thru my chronogragh any go from there. Any suggestion

THANKS

Steve

Soft Brass??? & Ejector

quote:

Originally posted by tsturm:

Soft Brass???

Not likely on factory ammo....

Weatherby brass is made by Norma. Norma brass is know to be a little softer than some of the hardest brands.
You didn't mention what action you are using.
You might check the ejector hole or slot for burrs.
I have handled thousands of factory once fired brass in both magnum and non calibers with ejector marks. Few of the rounds really looked like the pressure was excessive.

I have a similar issue with a Remington 700 in 35 Whelen. I have several 700s and this is the only one it happens with. Even with loads that are considered minimum or starting loads by reloading manuals I get a slight ejecter mark on the headstamp. I've tried different batches of brass and the same thing happens. I've even tried factory ammo and still the same thing.

There are no other signs of pressure and velocities are in line with the expected results from reloading manuals, so I've just accepted that this is just normal for this gun. But I still wish I knew why it happens.

Gentlemen

The action is a Mark V.

I shot a few loads thru my chronogragh today just to see where my velocity was.

IMR 7828 107 grains
Nosler Partition 300 grain
Federal 215 primer
Norma Brass
Muzzle velocity 10' from muzzle 2861 fps

IMR 7827 109 grains
Nosler Partition 300 grain
Federal 215 Primer
Weatherby Brass
Muzzle velocity 10' from muzzle 2921 fps

IMR 7828 111.0 grains MAX LOAD. Nosler # 4&5
Nosler Partition 300 grain
Federal 215 Primer
Norma Brass
Muzzle velocity 10' from muzzle 2991 fps

All three loads showed the slight injector marks and I could not see any visual difference between the primers. And bolt lift was normal. I have tried five different boxes of brass with no change. The only thing I can do know is see which loads groups the best and go from there.

Like duckboat said I just wish I knew why it was happening.

I also tried H-4831 with the same bullet, primer, and brass as mention above however, the load was eight grains below max and still get the slight injector marks.



Steve