Ammo issues
On my blog I posted about some ammo my brother was given. This is the followup post on the subject.
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I went to {edited to protect the dumb} in {edited to protect the dumb} Tn, and using calipers and such, they identified it as .308
Now a small gun rant.
When the smith told me it was a .308 he also said it was steel cased and that could be damaging to a firearm. I had read that before, but never have come across the situation, so had not gave it much thought. We talked about the brass wash/gilding then he said it.
I said “I thought at first it was a 7.62 � 51 mm. I got pretty close.”
Then he said “Well they’re the same thing”.
The problem is that they are not.
One of the better writeups on the issue can be found at Say Uncle’s Shooting Carnival, and even The Gun Zone has a good post on the subject.
While the 7.62mm NATO cartridge has a maximum chamber pressure of approximately 50,000 pounds per square inch (psi), in the SAAMI book the .308 Winchester has a MAP (maximum average product) pressure of approximately 62,000 psi* (each by conformal transducer measurements, and therefore comparable). This is not to say that all .308 Winchester loads will develop such pressures, merely that they would be within manufacturing tolerances if they did so. Firing .308 Winchester ammunition in a firearm specifically chambered for the 7.62mm NATO risks damage to the firearm and injury to the shooter.
When even gun smiths are giving out bad information how can newbies to the shooting field figure it all out? I’ve never shot a .308 or a 7.62X51mm, yet I know the basics of the issue on size and preasure.
Take a moment and verify all information you get over the counter. You get second opinions with doctors, why not gunsmiths?
December 12th, 2006 at 12:27 am
Try discussing legal issues with an FFL someday for an exercise in frustration. You think there is lots of misinformation floating around about cartridge pressures?
December 12th, 2006 at 12:48 am
I have an example: the old guy that runs a local shop here gave incorrect info twice. First, he said I was wrong that in Washington State you can carry concealed without a permit if you are in route to, in route from, or actively participating in a legitimate outdoor activity. It states this clearly in the washington laws.
Second, he was telling a fellow that the boat tail only improves ballistics below the speed of sound. Not true. The boat tail decreases “wave drag” associated with supersonic flight of the bullet. It also helps with pressure recovery and thus reduces drag when the bullet is subsonic. So he was half right.
December 12th, 2006 at 1:01 am
Ben. You have blogZpot in your link.
Did not know that about bobtail bullets. I’m just a plinker at heart.
December 12th, 2006 at 1:38 am
Yup. I paid for headspace gauging and chamber casting and found out that he had only chambered a hull. He’s still in business, unfortunately.
December 12th, 2006 at 7:42 am
I’ve heard some incorrect info as well as some outright lies from behind the counter a few times. I usually just smile, nod and walk away. Not everyone can be Tam.
December 12th, 2006 at 8:41 am
Also, the headspace is different.
Please see: http://www.thegunzone.com/30cal.html
December 12th, 2006 at 9:44 am
The rounds are quite different. I have both .308 and 7.62 NATO at home and the rounds clearly look different. My .308 Winchester Rifle shoots the surplus 7.62 just fine, but the surplus rounds look obviously different, and the cartridge neck is a wee bit shorter.
December 12th, 2006 at 12:50 pm
In terms of dimensions, the rounds are pretty much the same; I own both and haven’t noticed any obvious difference. It’s the rifles that shoot them that are different.
The problem starts when a person buys a 7.62 rifle thinking he can use .308 in it. A modern bolt action .308 made by a reputable manufacturer will shoot surplus 7.62 NATO just fine. A military semi-auto or older surplus 7.62 bolt action might not be able to handle .308 Win, for a variety of reasons.
I’m not sure what the advantage of using .308 in a 7.62 is, other than being able to legally hunt with it; the ammo certainly isn’t cheaper. That’s the advantage of buying a .308: You can use cheap 7.62 surplus ammo in it for target practice.
December 12th, 2006 at 1:32 pm
I learned along time ago not to trust the guy behind the counter. Most of the time he is just a warm body to sell ya something and will say anything to do it. I take upon myself to learn and vet any info. This has keep me safe and saved money in the long run. With the internet it is even easier now to find quility info on rounds and weapons. Be safe and keep in the 10 ring.
December 13th, 2006 at 12:15 am
7.62 Nato is milder than .308 Win. However, I own two rifles in the Nato config and I have done a lot of checking around and both of them are supposed to be robust enough to handle the .308 . One is an Ishapore Enfield, the other an L1A1. comments and opinions appreciated.