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Headspace confusion

833 views 3 replies 3 participants last post by  coz 
#1 ·
Ive searched for an answer to this question and haven't been able to find one so here goes.

I understand the concept of headspace (thanks to the sticky from Alpo), but what I don't understand is it's relationship to OAL since they're often mentioned together. It seems to me that headspace is only dependent on the length of the case from the mouth to the head (rimless cartridges) and has no real relationship to the OAL, which is determined by the bullet seating depth. A too short OAL could pass the plunk test, chamber and operate the action fine, but the bullet just wouldn't be extending far enough into the barrel (pressure issues aside) and a too long OAL would do the same, but just extend the bullet too far into the barrel. Where I've been puzzled is when someone gives an example of too much or too little headspace and then talks about OAL in the same sentence when it just seems to me like the case is just too long or too short causing the headspace issue.

So, am I looking too deeply into this or am I missing something? I suspect the second, so I'm asking the experts.
 
#2 ·
I believe the problem is caused by people that have no concept of what "overall" means. So they talk about "casing overall length" and "cartridge overall length".

There is no "casing overall length". If you have just one thing, it is simply "length". It is when you put two or more things together that you need "overall". Length A added to length B gives you OVERALL length C.

The only way length, as I see it, would apply to headspace, would be for straight-wall rimless cases (45ACP, 9mm, etc). They headspace on the mouth of the case. If the case length is too short you have excessive headspace. If the case length is too long, you have too little headspace

The only way I can see "overall length" mattering was if your bullet was seated out too far, so that it was jammed up against the rifling, and preventing the bolt from closing.
 
#3 ·
+1
 
#4 ·
The only way length, as I see it, would apply to headspace, would be for straight-wall rimless cases (45ACP, 9mm, etc). They headspace on the mouth of the case. If the case length is too short you have excessive headspace. If the case length is too long, you have too little headspace

The only way I can see "overall length" mattering was if your bullet was seated out too far, so that it was jammed up against the rifling, and preventing the bolt from closing.
Thanks for the explanation. It's exactly as I thought, but I wanted verification from an expert source that i wasnt missing something. Thanks again.
 
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