Thread: What happens when your case has lots of room left?

I've been reloading my 223 and 308 and always filled the cases up and sometimes compress loads with a drop tube.
But i have noticed with 303, 6.5x55 and 7.5x55, there is lots of room left but the max load has suggested not to load anymore.

I have some understanding of why the case should be reasonably full but need some more experienced people to tell me a bit more.
Any experts on this topic?

Use a slower powder

define "lots of room left" from my understanding of things the fuller the better to be sure BUT above say 70% is pretty normal and fine...IF you get less than 50-60% fill you can get flame from primer flash over top of powder which causes issues and a chance of secondary explosion....which i belive is when it goes baboom...had that with low charge of 760 in .270 years back with loads done for me by sports shop....I had to point rifle at sky and lower onto target to prevent it happening...wasnt flash I tell you.

You should have about 90 % full cases for good results, as suggested above use a slower burning powder which will fill the case more than the faster powders. The danger with a lot of space is poor ignition and possible high pressures.

Put the primer in first helps for me








Sorry couldn’t help myself these others seem to have better advice

With the 6.5x55 at least book loads assume you have a swedish m1896 action. The m 38 is quite a bit stronger and modern rifles stronger again.

Originally Posted by Marty Henry

With the 6.5x55 at least book loads assume you have a swedish m1896 action. The m 38 is quite a bit stronger and modern rifles stronger again.

Quite true my load for my Tikka in 6.5 x 55 is full, can't hear the powder, but I use a slow burning powder and it has a stronger action.

Follow the book to the letter and you will be safe.

Originally Posted by lee308

I've been reloading my 223 and 308 and always filled the cases up and sometimes compress loads with a drop tube.
But i have noticed with 303, 6.5x55 and 7.5x55, there is lots of room left but the max load has suggested not to load anymore.

I have some understanding of why the case should be reasonably full but need some more experienced people to tell me a bit more.

Any experts on this topic?

If you have to use a drop tube with the .223 and .308 you are using too slow a powder, AR2206H is a good powder for both cartridges,
the 303 6.5x55 and 7.5x55 are some of the earliest smokeless cartridges, The early smokeless powder was less powerful and bulkier
than modern powder as long as you don't go over max loads or under start loads you will be fine,
AR2206H works well in the .303 use 174 - 180 grain bullets they fit the throat better than lighter bullets

Originally Posted by shooternz

If you have to use a drop tube with the .223 and .308 you are using too slow a powder, AR2206H is a good powder for both cartridges,
the 303 6.5x55 and 7.5x55 are some of the earliest smokeless cartridges, The early smokeless powder was less powerful and bulkier
than modern powder as long as you don't go over max loads or under start loads you will be fine,
AR2206H works well in the .303 use 174 - 180 grain bullets they fit the throat better than lighter bullets

Yes, I go over the max load a bit for my 308 with 2206H for sure. but worked up to it though. Lapua thick brass didn't help.

If there is lots of space left in the case it can cause inconsistent ignition.
Picture a case only half full of powder. Depending on the angle of the rifle/cartridge, all the powder within the case could all go to one end or the other, or sit with more at one end than the other etc etc etc. This can cause inconsistency in ignition between the powder & primer. For example in a half full case - sometimes powder will be right up against the primer, and other times all the powder might be at the front of the case with a big gap between powder & primer.
The less the powder can move around in the case, the less potential there is for inconsistency caused by difference in the powder column & how it is ignited by the primer.

Can Cause mis fires or hang fires if you’re running primers which aren’t the hottest
Especially if you are using small primers in larger cases such as 308 etc

Q: What happens when your case has lots of room left?
A: Nothing.
But it is considered poor practice, even though no manufacturer, despite trying, has managed to replicate the "secondary explosive effect" or "flashover" or "detonation"
This is a myth that has been perpetuated for a long, long, long time.
Using bulkier/slower powder is good advice. alternatively top up the case with corn meal or dacron.

Ive had loads of win 760 that were done for me by sports shop..110grn projectiles and I asked for about 3000fps....if I didnt tip rifle to sky before squeazing trigger they went BA...BOOM it was VERY off putting and did terrible things to accuracy and flinchyness.... Ive remade same loads with a little more powder in them and they are lazer beams without issue...either the powder he used was ???damp/old n stuffed....or the lack of powder was causing it....that they would work if muzzle pointed skywards first suggests the second...

Originally Posted by ChrisW

If there is lots of space left in the case it can cause inconsistent ignition.
Picture a case only half full of powder. Depending on the angle of the rifle/cartridge, all the powder within the case could all go to one end or the other, or sit with more at one end than the other etc etc etc. This can cause inconsistency in ignition between the powder & primer. For example in a half full case - sometimes powder will be right up against the primer, and other times all the powder might be at the front of the case with a big gap between powder & primer.
The less the powder can move around in the case, the less potential there is for inconsistency caused by difference in the powder column & how it is ignited by the primer.

Cute picture. But no. The primer isn't a little spark at the end of the case, it will fill the entire case with flame.

And I'd be interested to see any evidence of the powder-location-vs-accuracy theory.