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An age old problem, I had a case head separate on my No4 Mk1 yesterday and as I had left my broken case extractor at home that was the end of the days shooting. I have been plagued with case issues on all of my .303 service rifles other than my P14 and I am at the stage where I feel like chucking all of my brass away after a couple of firings. This rifle just closes on a no-go gauge but not on a field gauge.

Any views on this anyone?

Change ther bolt head?

Hi ovenpaa.

I had the same problem with my No4, (head space not at fault) I relaod HXP brass, and found that I was getting cases seperating, these were 76 dated, but no other dates were affected. I was full lengh sizing. After advice 76 ones thrown out (bad year) I now neck size only, no further problems (even with the odd 76). Do you neck size, and what make are the cases. Just a thought.

This is S&B brass so not the best and was brass that I had full length sized and loaded quite a while ago, these days I neck size only. Maybe it is time to sling all of my brass and buy some decent stuff, fire once and then always neck size.

I have a couple of hundred rounds left over so I may just keep it for my P14.

ovenpaa wrote:An age old problem, I had a case head separate on my No4 Mk1 yesterday and as I had left my broken case extractor at home that was the end of the days shooting. I have been plagued with case issues on all of my .303 service rifles other than my P14 and I am at the stage where I feel like chucking all of my brass away after a couple of firings. This rifle just closes on a no-go gauge but not on a field gauge.

Any views on this anyone?

Ovenpaa,

Do simply consider the action was not designed for the round and load light.

A rimmed case, headspacing at rim allow regular brass flow, while headspacing at front wth a flexing action 'draw" the brass yo flow forward, who finally breaks at the weakest point...

Usualy, when a case come to excess extension, a darker ring can be observed outside where the rupture point starts. It can also be checked with a paper clip it better a piece of piano wire whose end has bee pointed and is bent at 90° over 2-4mm, inserted in the case and moved back and forth against the inside wall. If the wire 'hangs" at one point, usually 5 to 8mm from base, there is plenty of chance the case will give up on next firing.

R.G.C

ovenpaa wrote:An age old problem, I had a case head separate on my No4 Mk1 yesterday and as I had left my broken case extractor at home that was the end of the days shooting. I have been plagued with case issues on all of my .303 service rifles other than my P14 and I am at the stage where I feel like chucking all of my brass away after a couple of firings. This rifle just closes on a no-go gauge but not on a field gauge.

Any views on this anyone?

Sorry to hear your session was cut short.

Was there any damage to the rifle? I'm yet to witness this problem - what are the possible consequences for rifle, and/or shooter when this happens?

Sorry to hear your session was cut short.

Was there any damage to the rifle? I'm yet to witness this problem - what are the possible consequences for rifle, and/or shooter when this happens?[/quote]


As long as there is only a case separation , with no desintegration caused by a blow back, it remain more impressibe than anything else (although better to avoid it), as the gases are for most contained by the rear part of the case and the rear wall of the powder chamber expands tight in the barrel chamber, maintaining most if not all of the pressure.

Regarding the rifle, I have found the results of an old calculation I had to made years ago when it ws question of case stretching in this flexible action:

As the rifle was designed for the .303 cartridges, it was interesting to know the backtrust of each round. I do not reproduce all the calcualtions, suffice to say the powder chamber rear surface is about 10% less for the 303 as compared to the .308, when the nominal round pressure is 20% less, at 49000 PSI as compared to the nominal 60000 of the .308. The addition of those two differnces makes the .308 acting as a Proofhouse pressure test ( +25% normally) each time a .308 round is fired...

R.G.C

Cheers R.G.C. - I've only recently started reloading .303, and have hundreds of 'once fired' to get through yet...but will pay attention to this in the future...

I reloaded some 303 earlier and afterwards i always draw a small '1' on the cardboard to show how many times i've reloaded a particular box.Its Privi brass and one box has now been reloaded 7 times with no signs of fatigue.Not sure how many times i can neck size them,but will keep an eye on the cases.