7.62 x51 vs 308 winchester

[mcxring]

I hope someone can help me out with this confusion, I just bought a bushmaster from my local guns shop, under the empression it was a 308, after I bought it the salesman states, now on the the barrel it states that is is a 7.62x51, so you should only fire 7.62x51 ammo through it, what does this mean, do I have a 308 or not, he said something about 308 factory ammo is hotter than 7.62x51 and will damage the barrel?? I am a reloader, so if its a pressure issue can I compinsate, on my ar15 on the barrel it states 5.56 nato, I know that 5.56 ammo is hotter than 223, confused. any help Mike

 

[Minesweeper3433]

I presume this is a semiauto gas rifle? I shoot both in both myself without too much worry. Although those are semiauto rifles that get fed only factory ammo. Mostly surplus and hornady match.

 

[articmp]

NATO ammo is loaded hotter to run full autos. 308 WIN will run just fine in it. Do note that NATO brass is normally thicker, resulting in reduced case capacity, which can result in dangerous pressure levels if you throw a 308WIN powder charge in the NATO case.

 

[Laurie]

If you Google 7.62 v .308 Winchester, you'll find several websites including Wikipedia that list the differences. The main one is chamber length / headspace, the military chamber being slightly longer than the civilian to provide 100% reliable chambering with a badly fouled chamber, dirty or dented cartridges etc. Many 7.62 rifles have slightly tighter bores too than the 308's nominal 0.300/0.308" bore / groove dimensions and the standard military 7.62mm cartridge often uses a smaller diameter bullet at 0.3073-0.3078" in European manufactured stuff at any rate. (One of many reasons why surplus military ball often shoots poorly in a well dimensioned .308W rifle.)

As a handloader, this won't be a problem for you at all. Just load the ammo to suit your rifle. Because of the long (and usually slack) chamber in military rifles, you'll likely get better results by setting the sizer die up to suit the chamber using a Hornady L-N-L comparator insert and headspace gauge 'D'. Screwing the die down to the default position will likely push the shoulder back too much. In a semi-auto rifle, you want to push the shoulder back somewhere around 0.004 to 0.005", and importantly ensure you don't produce any sized cases with insufficient headspace as you really don't want to risk the firing pin striking a cartridge with the bolt lugs only partly engaged as can happen with some rifle designs.

It may suit you too to use military brass rather than commercial stuff.

 

[mcxring]

Thanks for the feedback, I feel better now, just another advantage to reloading
thanks again Mike

 

[Turbulent Turtle]

JUst for grins, I checked the Bushmaster web site for you and everywhere they talk about ther 308 rifles, the specify the caliber as .308Win/7.62 Nato. They use that designation on each and every 308 rifle they have listed. My guess is the reason they specify 7.62X51 on the barrel is to make sure people don't try to use 7.62X39 ammo in it.

You might want to read this article, look down about 2/3 of the way.

http://www.6mmbr.com/308Win.html

In my experience 7.62 Nato brass is extremely thick because they do shoot it out of machine guns with very loose chambers and all manners of rifles made in various countries; the brass is thick enough to expand into the largest military chambers without bursting and since the .mil do not reload their ammo they do not care what shape it's in when it comes out. It is a <female dog> to resize some of these .mil fired cases.

Bottom line is you should place a call to Bushmaster, just to be sure, but my belief is that you rifle will fire the more powerful commercial .308 Winchester just fine.

 

[coreydelong]

NATO 7.62 LC brass is made by Federal and the cases weigh about darn near the same as a Federal .308 case... ~176g- 179g.

If you have a good load for Federal .308 brass then don't fret about it. If you have a good load for Winchester brass- which is much lighter... 155g- 158g then you will need to adjust your charge down if you're gonna load in NATO brass.

 

[BlackEagle]

I hope someone can help me out with this confusion, I just bought a bushmaster from my local guns shop, under the empression it was a 308, after I bought it the salesman states, now on the the barrel it states that is is a 7.62x51, so you should only fire 7.62x51 ammo through it, what does this mean, do I have a 308 or not, he said something about 308 factory ammo is hotter than 7.62x51 and will damage the barrel?? I am a reloader, so if its a pressure issue can I compinsate, on my ar15 on the barrel it states 5.56 nato, I know that 5.56 ammo is hotter than 223, confused. any help Mike

He is (mostly) correct. Most 7.62x51 nato ammo is not as hot as a lot of .308 Winchester ammo(the opposite of the 5.56 nato vs .223 relationship). The difference can be significant in some guns (mostly older military rifles I think). You shouldn't have any problems if you are reloading.

 

[fr3db3ar]

@ OP, I'm running a DPMS Oracle using LC once fired brass, 175 SMK/ 150 SGK Varget 44.5/46 respectively, 200 primer set to mag length and getting around 3/4MOA now that I've got a few down the tube.

You shouldn't have any problems running your reloads down the tube.