rimmed headspace

[tew45]

I built a 219 zipper on a K falling block action around 30 years ago and I made the headspace at nearly zero. I understand this is under minimum and would like to know if this makes a difference. If so what and why would that be other of fit with brass differences?

[pietro]

.

If you're reloading the same brass, there should be N.P. with normal case re-sizzing - but a different brand of brass may/may not be too thick for the block to rise enough to lock up properly (if at all).

[LAGS]

I set up the headspace on my rifles at nearly zero on the Go Gauge.
I have found no problems , especially with Rimmed cartridges.
I actually found it better when you are shooting Spam Can military surplus ammo.
I E.
Like my 8mm Mausers.
The bolt closes with a very slight drag when I shoot commercial or handloaded ammo.
But the bolt just flops closed if I am shooting most military surplus ammo.
Seems like the military ammo may start off with the shoulder being set back to allow for dirt and crud you may find when using the rifle in battle conditions.
Rounds like the .303 headspace on the rim.
So the shorter casing dimensions or the sloppy chamber allows the fired casing to just Fire Form to the chamber you have.
But when you reload those casings , do not push the shoulder back much if at all.
It will make your casings last longer.

[M-Tecs]

Even at zero you should have no issues since the rims will be less than .063". SAAMI spec on the parent cartridge is .063" - .010". The headspace spec is .063" - .070".

On rimmed or belted cases with a shoulder I set headspace per the shoulder and not the rim or belt. Same for reloading I set the dies for .001" to .003" shoulder bump.

[Gtek]

With those rims running .060" or less on about every piece of brass I have touched, sounds like you built it just right to me.

[tew45]

I made a mistake when forming the brass from 30-30 once fired. I did not realize the trim die had to be bottomed (pressed down 2 or 3 times) to form the base to proper dimensions. I thought the die was just for case length. The reformed cartridge would not fully seat so head space was less than desirable. Now I have .030 headspace which will allow most rim thickness variations and allow good extraction unless I load too much surplus Egyptian 8MM Mauser powder.

[405grain]

.030" of headspace!!! That's way too much! With nearly 1/32" of headspace your risking a case head separation on the first firing. Hopefully this was just a typo and you actually meant .003" of headspace. If you actually have .030" of headspace DO NOT fire that gun.