UMC .303 Brit Brass?

[Hitzy]

So I'm new to the .303 game and just fired off a couple boxes of this stuff through my new to me P14.......
There is a considerable expansion ring below the case head (where it's suppose to be, just bigger than I'm use to seeing) but it doesn't go completely around the case, but almost. Now, federal brass in my AR does the same thing and I know the headspace is dead on sammi min spec and no other brass does this in my AR. I think the fed brass is just a touch undersized in the base area which makes the expansion ring look more pronounced.
So, is this common with UMC brass? Should I be worried? I want to keep it for neck sizing down the road when I start loading. I also don't want to by a $25 box of winchester ammo just to check to see if it does the same thing......

 

[Gatehouse]

Hitzy, I think it is common in alot of 303 chambers. I've reloaded UMC brass a number of times for SMLE's and havent' had aproblem, but there is an expansion ring as you described.

I'd neck size a coupel of cases and keep using them to see what happens, checking inside the brass at each firing for seperation signs.

 

[TheTooner]

Sounds like mine, too. I have reloaded a couple of hundred UMC cases for my No4Mk2 (gunsmith assures me the headspace is fine on this one). I necksize only, and most are on their fifth time used and still o.k. I have also used some Federal brass and it doesn't display the expansion to the same extent.

 

[John Y Cannuck]

It's common in other brands of 303Br brass too. Maybe a bit less pronounced in Winchester, but common just the same. It's also quite normal for the ring to go only part way round. If it really gets pronounced, chuck it. neck sizing, as you've already figured, is the way to go.

 

[Why not?]

Okay, Boys, here's what is going on...............I think.

The chambers in the military 303 rifles were purposely cut oversize to ensure easy chambering in battlefield conditions. Some are almost 15 thou too big at the base. When you chamber a round the extractor does not grip it tightly enough to hold it in place and it lays on the bottom of the chamber due to gravity. This is because the entire chamber is oversize and the case body gets no support at all behind the neck.

When the rifle is fired the expansion all occurs upwards, away from the contacting surface of the case and you end up with a case that is out of round, hence the uneven expansion ring.

If you really want to demonstrate this to yourself, just fire a few cases in your rifle with the headstamp in the same postion each time and fire one normally, one with the rifle upside down and a couple with the rifle turned 90 degrees each side of normal. You will see the uneven expansion ring is always opposite the lowest point of the chamber when fired.

Neck sizing, as Tooner says, is indeed the answer to increased case life, especially in the Lee Enfields.

Ted

 

[KDG]

Mine will do the same thing to UMC and Federal brass. It hardly ever does it to the Winchester brass though. Maybe the Win brass is thicker at the web area than the other two?
For me, the Herters brass from Higginson's is the cats ass for loading .303 followed by Winchester and S&B. I neck size only and I'm on the 5th reload of S&B brass with NO signs of case separation.