Home Forums Reloading Big Game Rifles headspace - how much is too much?

I just purchased a nice old Mauser '98 in 7x64. I fired a dozen cartridges this afternoon. I measured the headspace, using the Hornady headspace tool and my digital calipers to compare the difference between fired and factory new cases. From base to datum line on the shoulder, the cases have expanded is 0.012". The measurement is the same for PPU, RWS, and Speer cases / ammunition. Is this too much? My understanding is that a difference of 0.010" is about maximum. Your thoughts?

I wouldn't worry about that too much so long as you set up your sizing dies properly to your chamber

Or would it be possible to form 7x64 brass from 280 Remington brass?

Looks like min to max should be .010... so if you are expanding .012 from a shell that is inside that area somewhere you have some loose headspace.

to that end, don’t size down too much and you are in better shape, but setting the barrel back just a tad won’t hurt.

Look at line “F” ... max / min ...

thanks Spotshooter, that is vey helpful.

You haven't said you'll be handloading. If so, the brass is now ready to neck size or PFL resize. (If not, the brass has survived firing and shows to be safe in the Mauser.)
Although the .280 Remington brass may slip into the bolt just fine, be aware that the base has slightly different dimensions from true 7x64 Brenneke.

It’s my understanding and experience that brand new brass is undersized allowing it to fit even SAMMI minimum chambers. I would be curious to see if like another poster stated if it’s minimally resized just to chamber say .002 bump if the brass is just going grow .002.

RCBS makes + size shell holders For 308, and 223 based cartridges that can give you some extra headspace when resizing brass as well, but I’m not sure they would work for your application.

Yeah, and so does Redding. But you don't need special shell holders, just adjust the die for the right amount of shoulder bump and be done with it.

IMO .012" headspace is a lot, but not as uncommon as many people think. I've seen worse than that from following the directions of FL dies in some cartridges; I'd wager there are a lot of people here on the 'fire who are sizing their brass to that much headspace or more and don't know it.

If you are planning to reload that brass, just make sure to adjust for the right amount of shoulder bump (.001-.002" is good). If you don't load your own and are just shooting factory ammo, honestly it's probably ok to just keep shooting it as-is.

I called the vendor, and he was good enough to allow a return and refund. I just don't want to fool with that much headspace. I have two other 7x64's and keeping brass separate or worrying about a head separation just isn't worth the trouble for me. Thanks for all the comments and guidance.

Did you compare the same measurements with your other 7x64 rifles? IMO you're probably making much ado about nothing; it's very common for factory ammo (and even component brass) to have at least .010" headspace in correctly cut chambers.

.012 headspace in a new off the shelf factory rifle or a custom job I had commissioned would have me muttering and sending back. A used gun would have me conniving with the sizing die and living with it if I could and the gun was worth it.

Yes, my Sako M85 has about .004" headspace and the Steyr Mannlicher about 0.006" Quite different.

Just as a FYI... most cellofone tape is .0015 to .002 thick...

So if you take a piece of tape and put it on the base of a factory round... trim the edges with an exacto knife, then chamber it...
Put on a second piece, now you are around .004...
The third gets you to almost 6 thousands... and so on..

Measure your tape thickness before you do it and you know where it is with this trick.

At some point it’s going to bind.. and that’s when you hit your headspace limit

Just for reference, I compared the min./max. chamber and cartridge drawing from SAAMI, and found some interesting results. All three examples are typical of their general configuration.

.30-'06: The fit range was from .0039" interference to .0131" clearance. .0054" average.

7mm Rem. Mag.: The fit range was from .0091" clearance to .0261" clearance. .0176" average.

.30-30: The fit range was from .0173" clearance to .0473" clearance. .0323" average.

If I can make some assumptions from your comment, I think you're talking about headspace as measured with gauges in the chamber. What I'm talking about is actual headspace - the clearance between the cartridge and the chamber, which in the case of handloads has only a little to do with how the chamber compares to a gauge. A good reloader can minimize headspace in almost any chamber, but a lot of factory ammo is undersized to be sure it fits everything, and results in significantly more headspace than what a gauge tells you.