Thread: Headspace

I compared the headspace between two tikka t3s today. both .270 cal. there was a good three mm difference between the two rifles. Is that bonkers or kinda normal?

3mm is a lot might be time to get a gunsmith to have a look how did you check it

Do you mean 3 thou difference?

3mm is a chasm. I hope you’re measuring it wrong somehow.

Bonkers

Checked with a hornady headspace guage and bullet comparator. Maybe someone on the forum with a tikka .270 could tell me what their head space is? I'm measuring using nosler 140g bt , nosler 150gn partition and hornady 145g eld-x. And yes definitely mm. .12 of an inch= 3.048mm

Originally Posted by Grubby

Checked with a hornady headspace guage and bullet comparator. Maybe someone on the forum with a tikka .270 could tell me what their head space is? I'm measuring using nosler 140g bt , nosler 150gn partition and hornady 145g eld-x. And yes definitely mm. .12 of an inch= 3.048mm

That is measuring from the leed to face of the bolt, which is not headspace. Headspace is measured with gauges that measure from a point specified on the shoulder of the chamber (that point varies with different cartridges) to the bolt face. A rifle with 3mm excess headspace would not fire unless the cartridge was held by the extractor, and if it did fire the case would rupture with 'interesting' results!

Yep interesting results sounds like "Oh I'll give that a go"! year nar......MUMMY no son I'm not ya mother I'm Darwin here's your reward

What you are actually measuring is the seating deapth for the bullets. This differs between rifles as chamber reamers wear during use in manufacturing and rounds fired over the rifles life. One rifle appears to have more throat erosion then the other.

Whatever the OP is measuring sure ain't headspace.

Have a read:
https://www.brownells.com/guntech/he....htm?lid=17125

Thanks for all the sound advice guys. I guess I was using the wrong terminology. This is what makes the forum so good...... Sorting out the novices like me.
It was the newer rifle that had only fired 40 rounds that had the longer seating depth. The older rifle with around 600 rounds had the shorter seating depth.
Thanks again for the help.

For reference, 0.2mm growth in one on my rifles starts to get sticky to chamber and needs a bump to get it back to easy chambering.

3mm headspace is what you get in a Mosin Nagant, not a Tikka.

Originally Posted by dogmatix

3mm headspace is what you get in a Mosin Nagant, not a Tikka.

And it will still shoot well!