Headspace guages

[iusmc2002]

Are the headspace gauges for a 7mm Rem Mag and a 300 Win Mag interchangeable? I also was wondering if the 30-06 and 338-06 gauges were interchangeable?

Read More

 

[nwbobber]

No. The case dimensions of 7mag and 300 are quite different. The 06 guages might be of some use if you had the bigger one, but the 338 neck won't fit in a .308 hole.

 

[MountainBear]

Actually, both the 7mm and .300 use the belted magnum headspace guage. And since the headspace guage doesn't go into to barrel (just the chamber, past the datum point), I believe the .338-06 and .30-06 should both work on the .30-06 guage, but I am not 100% sure if the datum point on the shoulder is moved when the .30-06 is necked out to accommodate the .338 caliber bullet.

Forster Headspace No-Go Gage 30-06 Springfield 25-06 Remington 270

BELTED MAGNUM CARTRIDGE HEADSPACE GAUGES | Brownells

You are correct that the chambers are significantly different, but the chamber dimensions are less important that the location and dimension of the datum point. The datum point is the point where headspace is measured and varies based on the cartridge. On a .30-30, it headspaces off the rim. On a belted magum, generally on the belt. On a rimless cartridge, its generally a point roughly midway on the shoulder.

 

[Silver Hand]

MountainBear is correct when indicating the .300 win mag and the 7MM Rem Mag head space off the belt. I believe a common measurement is .220 in and .223 in for the .300 Mag.
Silver Hand

 

[Straight Shooter]

Yes to both questions. All the belted mags except the small 240 and 378 based Weatherby's use the exact same gauge. <broken link removed>

 

[nwbobber]

Of course. I was thinking case gauge. Doh.


.

.