.308 vs. 7.62x51mm

Apparently the maximum cartridge headspaces are the same, but the chamber headspace is different.  According to one article (apparently by SayUncle, on an early team blog with Eric S. Raymond, Smallest Minority, and others):

Chamber Headspace
	7.62x51mm	.308 Winchester
Go	1.6355"	1.630"
No-Go	-	1.634"
Field	1.6455"	1.638"

Cartridge Headspace
	7.62x51mm	.308 Winchester
Minimum	1.630"	1.627"
Maximum	1.633"	1.633"
Average	1.6315"	1.630"

SAAMI has a .308 Win spec up on their site.  It would seem to indicate that the min/max dimensions for .308 are 1.630"-1.640" chamber and 1.627"-1.634" cartridge, slightly different from the above, although there have been revisions of the standard.  I'm still looking to see if the NATO standards are available.

According to an old rec.guns post by Bartbob: "New cases typically end up with a fired-case headspace dimension of about .001-inch shorter than the chamber's actual headspace."  So if using fired brass to estimate chamber headspace, add 0.001" to the mic'ed dimension.

As an aside, TM 9-1005-223-10 is the M14 operator's manual.

M14 Info (ChiComs & Mags)

Rifle Company's forums have some info that I should troll through.  One thread on M14s:

One very nice thing about the Polys (& Norincos) is that geometry/dimension wise, the receivers are pretty much spec with USGI receivers. Unfortunately, with the Springfield made receivers that may be a hit or miss proposition. If one is planning on scoping their rifle, one might be better off with the Chinese made receivers. There are too many horror stories floating around about SAI receivers not being in spec, and needing a specially machined mount to work. Smith Enterprises supposedly has a special setup for measuring this. Plus, the bolt holes for the mounts are often miss machined/drilled/tapped on the SAI receivers.
The major "problem" areas for the Chinese receivers are:
#1. Sight knobs may be soft. Easy fix. Garand kobs work, and aren't very expensive. Note, all Chinese made knobs are marked WCE.
#2. Trigger/hammer may be soft. Easy fix. Again, Garand parts work, and aren't very expensive. Chinese made hammers and triggers are unmarked, while USGI hammers and triggers are stamped with letters and numbers(triggers may be iffy).
#3. Op rod spring may be a bit small and soft. Very easy fix. Replace with USGI spring.
#4. Stock is soft and ugly. Easy fix. Replace with USGI stock. Though there needs to be a slight mod to the stock to the shorter Chinese connector lock pin to stay in place.
#5. Bolt may need replacing. Most difficult fix. Hopwever, just replacing the bolt with a USGI bolt fixes any headspace issues. Often, it requires very little work other than a bit of lapping.
None of these fixes is expensive, and most can be done by the person with little or no experience.
At a good enough price, and I could easily talk myself into another Chinese rifle...............not that I need one. Unfortunately, the price keeps going up, since more and more people are finding out how good a bargain they are.

Another good one is a post on the differences between Chinese and USGI parts.

There's also a post regarding how to tell USGI mags from fakes.

Spring Link Dump!!

Some of these have been in my reader for a while.

Email from the Koch Institute regarding the Kochs' dispute with Cato: At first I was highly disappointed at the notice of the "takeover bid", but to be honest, I wasn't even aware of the history that Cato was originally the Charles Koch Foundation.  Now I'm not sure what to think.  It seems to be a trend that some of these advocacy organizations turn out to be driven primarily by the egos of their executives, e.g. Wayne LaPierre at the NRA.

So it turns out that extreme liberals don't really understand their opponents positions on the issues.  Surprise, surprise.  I've found empirically that they tend to not spend the time to educate themselves, preferring to wallow in their own poorly-formed, ill-considered ideology.  The study referred to is interesting.

From WSJ:

• Gardening tips for beginners.  I have dirt and seeds.  Now what?
• The end of the sophisticated playboy era.  The nouveau rich don't know how to live.
• How to tell when it's just another fight, and when it's over.  One can always make it work—it just depends on how much one is willing to sacrifice.  If both people are willing to sacrifice, that's a relationship that will survive.

Regarding the Trayvon Martin case:

• Thomas Sowell's Race and Rhetoric and some more commentary on "race hustlers".  Headline from the early '90s: "White-Black Disparity in Income Narrowed in 80’s, Census Shows"—what happened since the Reagan Era?
• John Lott's opinion on the relevance of Stand Your Ground to the case, and follow-up piece on Fox.

An opinion on the use of the term "gun culture": I disagree, because the extreme left has made this a culture war.  Nonetheless, it's an interesting point.

Federer Lindor Commercial

While the wife watching the Sony-Ericsson Open, we saw the Lindt commercial with Federer.  I fly fairly regularly and have grown to despise the TSA, but that's some funny stuff.  The 30-second version is on YouTube, as well as an extended version (which is even better).  There's even a behind the scenes video!