View Full Version : 6mm ackley head space

02-03-2008, 02:02 PM
how can i measure the head space on my gun.tried the scotch tape method
had two layers before i felt resistance. did not dissasemble the bolt.
thanks for any help

Dennis Sorensen
02-03-2008, 02:14 PM
To correctly measure the headspace you need a steel AI headspace go gauge... it is tighter than a non AI go gauge...

... if you don't have a gauge.... you can make your ammo fit correctly...

Remove the firing pin assembly.. it is important that you have to feel resistance closing the bolt on factory brass or on your fully sized 6mm brass...

If you can not feel the bolt close firmly, you need to expand the necks larger than the chamber size and then partially resize the neck leaving a false shoulder that will contact the chamber forcing the case hard against the bolt face when the bolt is closed...

02-03-2008, 04:04 PM
It sounds as if someone rechambered it to the AI version without setting the barrel back. If you can close the bolt on full length sized brass as Dennis explained, the headspace is already too long. Find a sandard 6mm Remington "go" headspace gauge and if the bolt closes on that, the headspace is excessive.

02-04-2008, 10:21 AM
forgot to mention that i tried tape test on fired case as well.itseems like normal 6mm would work as thats how u make improved cases.

02-04-2008, 01:15 PM
To make improved cases, you need to start with the factory 6mm case, full lengrh sized in a correct chamber. I cannot overempasize CORRECT. The AI chamber is shorter than the regular 6mm and when you insert the regular 6mm case you should feel some resistance when you close the bolt. They next need to be fireformed in that chamber.

Like I said before, I think your chamber is already too long if you can close the bolt on a new 6mm case.