Q: I own a Lee Enfield .303 rifle and reload ammunition for it. I’ve been a reloader for over 30 years and neck size all the cases I reload whenever possible.
The problem is, I am having trouble with case-head separations about 90 percent of the time.
A year ago I took my rifle to a gunsmith and he replaced the bolt head with a longer one that he said would solve the problem, but it didn’t. What do you think is causing this problem if it is not excessive headspace?
Oliver Hancock
A: Case-head separations are a common problem with many old ex-military .303s and, adding to the difficulty of rectification, the trouble may not be entirely due to excess headspace.
With this bottle-necked rimmed case, headspace is controlled (in respect to bolt closure) by the case rim in relation to the bolt face.
If this were the only criterion, it could easily be corrected by replacing the bolt head with a longer one which lengthens the bolt slightly. Lee Enfield bolt heads come with different numbers for this express purpose.
It sometimes happened that the chamber was cut long from base to shoulder, and upon firing, case shoulders will be moved forward to contact the chamber’s shoulder, causing case bodies to stretch even though the bolt may be headspaced correctly on the case rim.
I have a sneaking suspicion that this happened with many .303s that were loosely chambered to allow for oversize wartime cartridges and for any dirt and debris that might get into the chamber under battlefield conditions.
Seeing that your rifle’s headspace is correct, it is likely that a too-long chamber is the problem. There are two ways of rectifying this.
The first is by not full-length resizing cases. Instead, neck them up to 8mm or larger, and then partially size them back down (forming a secondary shoulder on the neck) until the bolt closes with a slight feel. After this, neck size only.
Alternatively, you can get your gunsmith to set the barrel back one complete turn and re-chamber it.
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