How much headspace is considered excessive for 6.5G?

[R2BRO]

Say for example, a fired brass out of my rifle measures say at 0

Next, i start resizing it, and of course depending on a stroke/variation i will be pushing back from 0 a different amounts, usually i set it to push back to -5 thousands.

My question: If in rare occasions i pushed too much, say -7 thousands, is it still well before the dangerous "excessive headspace" margin or it is too much of a headspace and can be dangerous?

Side note: I measure the factory Hornady BTHP rounds with same milled case gauge and it shows -6 thousands... so i personally think that -7 is not really *much* lower than what Hornady has for its rounds.. But i just wanted to have confirmation from you guys too just to be 100% confident.

thanks.

[lazyengineer]

In my experience with other casings, 7 thousandths is fine. Do it every cycle and you'll likely get a head separation in 4 or 5 cycles.

Personally, in my experience, there is no safety issue with excessive head-space. What will happen is the casing will stretch forward to fill the chamber, and if it's real bad, the casing will break in half. Which is not big deal, as the break is near the middle, and it only takes a small portion of the back of the case to hold seal. The gun doesn't blow up, it just jams when the front of the casing stays stuck in the chamber during the cycling, and that's about it. It's not the dangerous situation everyone makes it out to be.

Actually, I kind of think it's more dangerous to have too little headspace, and the gun doesn't fully lock into the battery because the round doesn't fit. It shouldn't kaboom as the firing pin shouldn't be able to contact the primer if it's not locked. Shouldn't. ... shouldn't. Meanwhile, that'll jam up a gun pretty good too. The Garand Collectors Association saw articles on two M1 Garand that Kaboomed during formal competition, from just this. The casing didn't lock into battery right, due to too tight of headspace (i.e. 0 thousands or less), and Kaboomed from slam-fire or out-of-battery.

[R2BRO]

thanks, understood!

[A5BLASTER]

All you need is 3 to 4 thousands on your shoulder bump for grendel at brass. More then that and your going too kill your brass life.

And too much headspace is a very bad thing in a ar of any caliber. It's not too come off rude but I would never take the advice of someone saying excessive headspace isn't dangerous.

You will understand when more knowledgeable members read this thread.

[Klem]

I have had two incipient case separations in an AR over the years, both caused by excessive headspace...They were exactly as Lazyengineer described. Slightly bigger bang than normal and more smoke at the chamber but nothing broken except the cases. The gun still functioned fine for years after. I was lucky that both front ends came out without much poking around.

I will add that when the case separates it etches a noticeable circular shallow trench in the walls of the chamber from the concentration of heated gas. Didn't seem to affect anything, including accuracy. But it was always there...reminding me...

7-thou is fine. A lot of first firings from factory cases are more than that.

[R2BRO]

uhhh...does it mean i need to test a pile of sized brass again to find those couple -7 ones i put there? or its ok for this time but just keep -3 to -4 for next time?

[Klem]

uhhh...does it mean i need to test a pile of sized brass again to find those couple -7 ones i put there? or its ok for this time but just keep -3 to -4 for next time?

No...You will be fine.

[R2BRO]

oh darn..thank you Klem!

alright ill go on as is, but will set back sizing die to make -3/-4 an average

[mtnlvr]

How much headspace is considered excessive for 6.5G?

Generally speaking, excessive headspace is when a bolt closes on a no-go gauge. There is nothing that you can do in your reloading process to change a firearm's headspace. Headspace can change over time as parts fail or wear.

What you're talking about, is case shoulder setback.

I know you, and the majority of people reading this understand the difference, but it would be helpful for those that don't, to try not to accidentally mislead anyone.

As mentioned, you'll be fine at 0.007" setback, it's just more than necessary.

[RMiller]

I am glad to find thus thread, I have been wondering the same thing myself.

In my case I set my dies to around 3-4 thousands setback for a rifle requiring the dies be backed out but then my latest barrel I bought is only 2 thousands less headspace so my setback for that barrel is 5-6 thousands with the dies set the same.

Time will tell how long the cases last with more setback but this thread is encouraging.