I have a 300 Norma ptg go gauge. The go gauge is .010 longer than my shortest piece of 80 new Lapua cases. It is .006 longer than my longest of 80 pieces of nee Lapua brass. I really only intend to shoot Lapua brass. So what I would really like to do is use my longest piece of Lapua brass as my go gauge and add .004 brass shim behind my longest piece as a no go. Does anyone know the actual tolerances for headspace for the 300 norma? Any recommendations for my scenario?
300 Norma headspace question
- Thread starter DJ Fergus
- Start date
Help Support Long Range Hunting Forum
sable tireur
Well-Known Member
- Joined
- Oct 8, 2010
- Messages
- 3,406
Here is the brass case length for the .300 Norma Mag:
And you're telling us that your 'Go-Gauge' is 0.010" longer than this case?
And you're telling us that your 'Go-Gauge' is 0.010" longer than this case?
Not overall case length but headspace length on my go gauge is .006 longer than my the longest headspace of 80 pieces of Lapua brass and .010 longer than the headspace of the shortest piece. In other words, if it's chambered with in such a way that my go gauge is the absolute max max length that can be chamberd I will have .006 to .010 headspace on my 80 pieces of new Lapua brass. I'm not saying that's a problem but I would like minimal headspace. Thoughts & suggestions welcomed.
DUSTY NOGGIN
Well-Known Member
fire form em .
and take the extra capacity
and take the extra capacity
Yeah, I've thought about that also. Not against that idea.
Would end up being .010 headspace on some of the cases but in reality after chambered with a .004 shimed go gauge as no-go gauge it could end up being more than .010 up to possibly .012. i have no idea what CIP has for a window on headspace. I've searched online with no success. I had a 25-06 with .021 totally headspace and it shot ok but it wasn't ideal.
If building a Wildcat, I will use a go gauge since with Wildcats I am usually improving and/or moving the shoulder.
For SAAMI or CIP spec cases, I never use a gi gauge. I take 3 of the longest pieces of virgin brass, size them in my FL die to make sure they have correct dimensions, then use them as headspace gauges with shims on the bolt face. Just make sure that your sizing die will be able to knock the shoulders back a couple thou when resizing. If you use the shortest cases, your die may not be able to touch the shoulder to set back a fired case
For SAAMI or CIP spec cases, I never use a gi gauge. I take 3 of the longest pieces of virgin brass, size them in my FL die to make sure they have correct dimensions, then use them as headspace gauges with shims on the bolt face. Just make sure that your sizing die will be able to knock the shoulders back a couple thou when resizing. If you use the shortest cases, your die may not be able to touch the shoulder to set back a fired case
