Thread: 303 Query

I am ready to load 100 rounds of annealed used brass. FLS. My mate has given me a loaded commercial PPU round. The shoulder on it is very pronounced akin to the shoulder on a standard 243. There is no way I am going to come close to that shoulder if it is the reference point.[profile]. The commentary is that you neck size for this calibre. You are not going to get the same sizing to a commercial round by neck sizing so why the difference? Done thousands of bottle neck, learnt 44 mag but this is a different kettle of fish.

Each calibre cartridge case is differant to other calibres. The shoulder on a 243 bears no relationship to the shoulder on your 303Brit case

The .303 headspaces on the rim not the shoulder, the cases last longer if neck sized, reloading was not a thing back when the .303 was designed.
don't go for max velocity reload for accuracy a 174 grain bullet at 2200fps will kill any animal you are likely to shoot you don't need 2400fps

....but 2400fps is nicer, and it's not as if .303 cases are made of gold. You should be able to load to that velocity without abusing cases by using a slow powder, etc. But if you shoot cast lead bullets, then you will be best under 2000fps.

What is more inportant than shoulder sizing is if the bolt will close on the fired case. If the shoulders are back enough to allow for this then don't worry.

As said above, the .303 headspaces on the rim, not the shoulder. This allowed chambers with generous shoulder space and aided mass production and also imparted some tolerance to dirty chambers under field conditions. If you are of clean habits, then just neck size and let your cases stay expanded to take up the whole chamber.

Originally Posted by Cordite

As said above, the .303 headspaces on the rim, not the shoulder. This allowed chambers with generous shoulder space and aided mass production and also imparted some tolerance to dirty chambers under field conditions. If you are of clean habits, then just neck size and let your cases stay expanded to take up the whole chamber.

Check the case works in each rifle if you shoot more than one .303 rifle.

Greetings,
There are differences between the chamber and cartridge shoulder angles on the .303. The chamber shoulder is much steeper. This may be due to the forming of cases with the cordite charge in place. Keeping pressures down a bit and neck sizing will deliver decent case life. This is just due to the .303 being a very old cartridge with looser tolerances and a rear locking action. If you want max loads you just have to accept short case life.
GPM.

I have been reloading and shooting 303 for 20+ years.
I'm up to 11+ reloads on my RP brass.

- Use cases in one rifle only
- Neck size with Lee Collet Dies
- Full loads using AR2209 and 174gr
- Occasionally anneal

In recent post on same subject there is great photo of two .303brit fired cases. It shows how vastly different chambers can be.this was wartime construction and as long as a std sized factory round chambered n fired it was near enough. Some chambers vastly larger than others.thus you keep cases for your rifle,for your rifle and if get others that have been fired elsewhere,check them in chamber before you start,check again after resizing,if they still won't fit.....ask someone cleverer than me how you can get them smaller lol.

One of the very helpful members here uses the 220gr woodleighs.
Trajectory of a rainbow apparently but hits like the hammer of Thor.
Rates them highly

The dimensions of factory ammo are such so they can chamber in all different rifles.

.303 cases stretch more than others so neck sizing instead of full length sizing, goes towards reducing that. That is why they recommend neck sizing.

Neck size the cases until one day you have difficulty closing the bolt, then you have to full length size them, and then keep going once again with neck sizing. Keep you eye on trim length after full length sizing.

.303 fired cases all come out different, because the chambers are often oversized. This means you can only neck size using brass fired in your rifle. (There is a high chance that brass fired in another rifle will not chamber in your .303 and vice versa.)


There is no point in reloading and accepting velocities as low as cheap factory ammo. There is no reason why you cant get the same velocity as the military ammo it was designed for. I load my .303 with 48 grains of 2209 and a 180 Speer, for 2420fps. I will also load it with 42 grains of 2208 and a 174g FMJ for 2500fps. These loads are appropriate for all .303 I have tried them in. Both loads have shown excellent accuracy in several rifles.

Originally Posted by John Duxbury

The dimensions of factory ammo are such so they can chamber in all different rifles.

.303 cases stretch more than others so neck sizing instead of full length sizing, goes towards reducing that. That is why they recommend neck sizing.

Neck size the cases until one day you have difficulty closing the bolt, then you have to full length size them, and then keep going once again with neck sizing. Keep you eye on trim length after full length sizing.

.303 fired cases all come out different, because the chambers are often oversized. This means you can only neck size using brass fired in your rifle. (There is a high chance that brass fired in another rifle will not chamber in your .303 and vice versa.)


There is no point in reloading and accepting velocities as low as cheap factory ammo. There is no reason why you cant get the same velocity as the military ammo it was designed for. I load my .303 with 48 grains of 2209 and a 180 Speer, for 2420fps. I will also load it with 42 grains of 2208 and a 174g FMJ for 2500fps. These loads are appropriate for all .303 I have tried them in. Both loads have shown excellent accuracy in several rifles.

Only problem with that idea is when you neck size a case
And need to full length size occasionally
Every time you full length size that ammo is different to the neck size and will shoot Differently
The best way is to anneal every shot and full length size that way your case is exactly the same every time not Different every so often because you had to size your brass

Not sure it will make enough difference to worry about in a shitty old 303 though
But having said that I wouldn’t trust a 303 chamber to be perfectly round ether which is required for neck size to work Reliably
So in an old rifle like that a full length size is the way to go

In a modern rifle a Partial full length size (Shoulder bump) is the way to go
90% of the world’s top shooters have gone away from neck size in favour of shoulder bump
Due to the above Reliability and consistency issues with neck sizeing

Its not like its a bench rest rifle. It was basically desighned to hit a person or scare the shit out of them if you missed

Originally Posted by blip

Its not like its a bench rest rifle. It was basically desighned to hit a person or scare the shit out of them if you missed

Exactly so just full length size for reliability

Originally Posted by rambo-6mmrem

Only problem with that idea is when you neck size a case
And need to full length size occasionally
Every time you full length size that ammo is different to the neck size and will shoot Differently
The best way is to anneal every shot and full length size that way your case is exactly the same every time not Different every so often because you had to size your brass

Not sure it will make enough difference to worry about in a shitty old 303 though
But having said that I wouldn’t trust a 303 chamber to be perfectly round ether which is required for neck size to work Reliably
So in an old rifle like that a full length size is the way to go

In a modern rifle a Partial full length size (Shoulder bump) is the way to go
90% of the world’s top shooters have gone away from neck size in favour of shoulder bump
Due to the above Reliability and consistency issues with neck sizeing

This avo loading 40gr 4064 with 180gr Sierra. All brass annealed. They are chambering unloaded so hopefully it goes well.

I just anneal mine and neck size in a lee loader. Mine are just rifles ill drag out for a bit of fun or if someone wants to shoot one to try it out. Reliability? Who cares not a life or death situation and sometimes the greek stuff doesnt go off even if it does chamber