Thread: "Air space" in 303 British and 308 Winchester caseloads...Dangerous?

Originally Posted by Kiwi Sapper

With reloading 303 and 308 I am now looking at reducing the projectile seating depth to reduce the "bullet jump" I currently have with commercial loads. Sadly, there are 3 gray areas of my knowledge.

1...Having entered reloading via black powder, I am very conscious of the danger from air space in BP rounds and with the reduced seating depth of 303 and 308 projectiles, is the increased airspace in the case a danger, as it is for B.P. I am using when using ADI AR2208.

If not, great, if so, would the usual space fillers for B.P. be suitable?

2...Reducing the projectile seating depth, results in less length of the projectile in the case. For safety and pressure, is there a minimum length of projectile required in the case.....or is it that it must just be solidly fixed?

3...Does the answer to 2 also apply to boat tail projectiles as they have a tapering end which, dependent upon the taper, reduces the ability of the case to securely hold the projectile?


Finally does the OAL measurement as given in the appropriate dies have any relevance to the above? i.e not to be exceeded under any circummstances.
Thank You.

I suguest you buy a reloading manual preferably put out by the manufacture of the projectiles you are using, load your ammo with the overall length as given
and the start load and work up in 0.5 grain steps until you find the most accurate powder charge this will give you a known load to check other loads performance
against, choose a powder that gives the best velocity with 90% case capcity compressing modern smokeless powders is not recommended when starting out,
With the .308 and .303 Brit 2206H and 2208 are the easiest to work with both lead and jacketed bullets for reduced loads use Trail Boss, Stay within recommended
powder charge weights and you can't go wrong, And forget about S.E.E it does not happen.