Bullet gas seal position when seating?

[DenisA]

Hi All,

I read in "The Book Of Rifle Accuracy" (I'm sure it was that one) that it is a fundamental practice for accurate hand loading, that the gas seal of the bullet is not pressed past the sized area of the case neck when seating bullets.

I haven't heard this before, I've tuned lots of accurate loads and only ever neck size 2/3 of the neck in SAAMI spec chambers always pushing the gas seal past the sized portion.

Is this common knowledge that I've just been unaware of?

If not, does it have any real merit?

Cheers,

[jasmay]

First I have heard, maybe I am our of the loop too...

[6602steven]

Assuming they mean the pressure ring like at the start of the boat tail I've never heard it should stay in the neck either. I do take it into account when measuring neck clearance though

Steve

[ShaneG]

Maybe it is to deny any problems with doughnuts which may have formed at the rearmost position of the sized area?

[KHGS]

Hi All,

I read in "The Book Of Rifle Accuracy" (I'm sure it was that one) that it is a fundamental practice for accurate hand loading, that the gas seal of the bullet is not pressed past the sized area of the case neck when seating bullets.

I haven't heard this before, I've tuned lots of accurate loads and only ever neck size 2/3 of the neck in SAAMI spec chambers always pushing the gas seal past the sized portion.

Is this common knowledge that I've just been unaware of?

If not, does it have any real merit?

Cheers,

Seating bullets below the sized area of the neck can upset bullet pull. There is usually a pressure ring at the base of the bullet, or in the case of a boattail bullet this pressure ring will be where the boattail starts. Seating the bullet with the pressure ring below the sized neck section can cause the bullet to have a lesser bullet pull than if it is not seated past the sized section. This is not so much of a problem with long bearing surface bullets as it is with short bench rest bullets. Also not usually a problem with VLD bullets that are shot "jammed". Shooting "jammed" bullets tends to negate slight variations in bullet pull. Another reason why I favour long neck cartridges.
Keith H.

[DenisA]

Thank you for the replies gents and your explanation Keith. Maybe this is a BR technique for shorter FB bullets. I realise that a lot of the authors of these rifle accuracy books shoot multiple disciplines competitively.

Glad to see that I haven't been ignorant of a LR basic.

Thanks again.