I think ur looking at the wrong drawing. Even the one you posted shows .277" neck Diameter +.002" tolerance.
I think ur using the wrong comparator. You should be using the .400" comparator. If that won't go over the neck there is big issues.
Brass Expansion
- Thread starter Mickp7
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What does the neck OD of a loaded piece of ammo measure?
ShtrRdy
Well-Known Member
Oops! Thanks for pointing that out. I corrected the post. Must not have had enough coffee yet.
SAC, 6mm x 30 degrees
slikmrc
Well-Known Member
I'm in the process of loading 6 CM Peterson brass, once fired. Using a Forster die with necked honed to .268, bumping shoulder .001. Fired neck OD is .275, sized neck is .271, loaded neck is .2715. Fired shoulder/ neck OD is .462, sized is.458. Looks like your chamber is big at the shoulder/neck OD. Hope this helps.
I went and looked at the SAC design for the comparator. I can see where their tapered design can be an issue if your chamber is too large and you're measuring the fired case and then the sized case. Don't think it's the body/shoulder junction that stops it but the neck/shoulder junction probably is. The body/shoulder junction should never contact the tool. Try a comparator that doesn't have the tapered part and you can probably get a measurement. Good luck to ya.
His fired diameter is .278, not .268. That might be .001 over after spring back but doesn't seem excessive.
I didn't look at the shoulder diameter. So you may be right but that's a LOT of reamer wear. Maybe not bored concentric?
slikmrc
Well-Known Member
When I was researching dies for the 6 CM I remember SAC stating Their die was tighter at .200 and opened up a little at the neck/shoulder area. I would give them a call and see what their thoughts are. Die may not be compatible with max dimension chamber.
.270
Interesting… my formed and loaded brass is .461 or .4 at the shoulder/body (just before taper to the neck) junction and .467 on fired brass. This is where I think the bore may be too large and why the comparator will not make it over.
Seekins suggested I send them the rifle, which I think I'm going to have to do.
