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308 and 7.62
Posted on 12/16/14 at 5:04 pm
Posted on 12/16/14 at 5:04 pm
help me out OB. do i have this right? 308 will fire from a 7.62 chambered rifle but a 7.62 won't necessarily fire from a 308 chambered rifle because of needed length inside the chamber. yes? no? am i all screwed up on this?
doing the research is kind of confusing me. i want to upgrade from the cheap-ish 308 i have now but i'd also like an AR10. if i wanted to go the build route, i don't want to limit the weapon if i could use both rounds.
doing the research is kind of confusing me. i want to upgrade from the cheap-ish 308 i have now but i'd also like an AR10. if i wanted to go the build route, i don't want to limit the weapon if i could use both rounds.
7
Posted on 12/16/14 at 5:20 pm to DLauw
7.62 by what?
.308 and 7.62 refer to the diameter of the actual bullet not the length of the case.
0.308 inches = 7.8232 mm
where as .300 = 7.62 mm
7.62 ammo frequently comes in three forms
7.62 x 39 and 7.62 x 51 7.62 x 54
the .308 cartridge is designed to fire through a barrel that measures across the GROOVES .308" or 7.82mm
the 7.62 x 51 NATO cartridge fires through a barrel that measures across the LANDS 7.62 mm
the 7.62 x 39 and 7.62 x 54 are actually using a 7.92 mm diameter bullets
.308 and 7.62 refer to the diameter of the actual bullet not the length of the case.
0.308 inches = 7.8232 mm
where as .300 = 7.62 mm
7.62 ammo frequently comes in three forms
7.62 x 39 and 7.62 x 51 7.62 x 54
the .308 cartridge is designed to fire through a barrel that measures across the GROOVES .308" or 7.82mm
the 7.62 x 51 NATO cartridge fires through a barrel that measures across the LANDS 7.62 mm
the 7.62 x 39 and 7.62 x 54 are actually using a 7.92 mm diameter bullets
This post was edited on 12/16/14 at 5:33 pm
Posted on 12/16/14 at 5:23 pm to DLauw
if it's anything like .223 vs. 5.56, it has more to do with chamber pressure, IIRC. 5.56 has higher chamber pressure so it's not safe to fire 5.56 in a rifle chambered for .223 only.
If chambered in 7.62, it should be good for .308 and 7.62 but not vice versa (if using the 5.56 vs .223 logic).
If chambered in 7.62, it should be good for .308 and 7.62 but not vice versa (if using the 5.56 vs .223 logic).
This post was edited on 12/16/14 at 5:26 pm
Posted on 12/16/14 at 5:24 pm to DLauw
I believe its opposite of the 223/5.56.
The 223 will fire in a 5.56 chamber, not vice versa. You cant fire a 308 win in a 7.62x51 but you can vice versa. I think the 308 win has a little more bite than the 7.62x51. Correct me if im wrong
The 223 will fire in a 5.56 chamber, not vice versa. You cant fire a 308 win in a 7.62x51 but you can vice versa. I think the 308 win has a little more bite than the 7.62x51. Correct me if im wrong
This post was edited on 12/16/14 at 5:26 pm
Posted on 12/16/14 at 5:25 pm to upgrayedd
Metric calibers for small arms are usually expressed with an "×" between the width and the length; for example, 7.62×51 NATO. This indicates the barrel diameter is 7.62 mm land to land, loaded in a case 51 mm long. Similarly, the 6.5×55 Swedish cartridge is fired from a 6.5-mm-diameter barrel and has a case length of 55 mm. The means of measuring a rifled bore varies, and may refer to the diameter of the lands or the grooves of the rifling; this is why the .303 British, measured across the lands, actually uses a .311-in bullet (7.70 mm vs. 7.90 mm), while the .308 Winchester, dimensionally similar to (but should not be considered interchangeable with) the 7.62×51 mm NATO cartridge, is measured across the grooves and uses a .308-in diameter (7.82-mm) bullet. An exception to this rule is the proprietary cartridge used by U.S. maker Lazzeroni, which is named based on the groove diameter in millimeters, such as the 7.82 Warbird
Posted on 12/16/14 at 5:28 pm to DLauw
I borrowed from another site
7.62 and .308 differences summed up:
7.62 has a longer permissible headspace for reliability in full auto weapons.
7.62 has thicker brass
7.62 is loaded to lower pressure (compare CIP specs to NATO specs since they use the same measurement standard)
Because the 7.62 potentially has a long chamber, the brass is made thicker and pressure kept lower to keep from rupturing cases. Firing a .308 round with higher pressure and thinner brass in a chamber with excess headspace (by .308 standards) is asking to blow up a case. Might not hurt the rifle but will probably scare the crap out of the shooter when he gets a face full of hot gas.
If a rifle marked 7.62 has the chamber checked and it falls within .308 headspace dimensions, firing .308 in it should be OK. Be cognizant of gas volume and pressure with piston operated rifles as too much of either can damage the operating system.
7.62 and .308 differences summed up:
7.62 has a longer permissible headspace for reliability in full auto weapons.
7.62 has thicker brass
7.62 is loaded to lower pressure (compare CIP specs to NATO specs since they use the same measurement standard)
Because the 7.62 potentially has a long chamber, the brass is made thicker and pressure kept lower to keep from rupturing cases. Firing a .308 round with higher pressure and thinner brass in a chamber with excess headspace (by .308 standards) is asking to blow up a case. Might not hurt the rifle but will probably scare the crap out of the shooter when he gets a face full of hot gas.
If a rifle marked 7.62 has the chamber checked and it falls within .308 headspace dimensions, firing .308 in it should be OK. Be cognizant of gas volume and pressure with piston operated rifles as too much of either can damage the operating system.
This post was edited on 12/16/14 at 5:29 pm
Posted on 12/16/14 at 5:29 pm to Bleeding purple
.223 and 5.56 can both be fired through same barrel as long as barrel is rated for the pressure created in 5.56.
Posted on 12/16/14 at 5:33 pm to Bleeding purple
Try to be helpful and get a down vote?
Well frick this thread then
Well frick this thread then
Posted on 12/16/14 at 5:43 pm to Bleeding purple
quote:
Try to be helpful and get a down vote?
Well frick this thread then
I had to give you another.Posted on 12/16/14 at 5:44 pm to Haughtonboy
so what ya'll are saying is.... just buy/order a complete rifle chambered in 308/7.62 NATO because i don't know/understand it enough to build my own.
it's never as easy i originally think it is.
appreciate the comments and explanations.
ETA: i upvoted everyone except for polypusher (don't know you)
it's never as easy i originally think it is.
appreciate the comments and explanations.
ETA: i upvoted everyone except for polypusher (don't know you)
This post was edited on 12/16/14 at 5:47 pm
Posted on 12/16/14 at 5:53 pm to DLauw
Just buy a 308 barrel and do what you want. Ever see 762 ammo on the shelf? Its pretty rare.
Posted on 12/16/14 at 6:11 pm to DLauw
quote:
ETA: i upvoted everyone except for polypusher (don't know you)
damnit
Posted on 12/16/14 at 6:17 pm to DLauw
SAAMI actually considers .308 Winchester and 7.62mm Nato to be the same round.
The hotter factory and handloads for .308 are actually not recommended in 7.62mm chambers, but, from an engineering standpoint, you should be okay.
This is not the "one way" compatible for .38special ammo in a .357 magnum firearm (or .44 Special in .44 Magnum) but not vice versa or the complex question with .223 Remington and 5.56mm Nato.
As a rule, .223 Remington is okay in 5.56mm chambers, but not the other way around. That can result in headspace and forcing cone issues.
The hotter factory and handloads for .308 are actually not recommended in 7.62mm chambers, but, from an engineering standpoint, you should be okay.
This is not the "one way" compatible for .38special ammo in a .357 magnum firearm (or .44 Special in .44 Magnum) but not vice versa or the complex question with .223 Remington and 5.56mm Nato.
As a rule, .223 Remington is okay in 5.56mm chambers, but not the other way around. That can result in headspace and forcing cone issues.
Posted on 12/16/14 at 6:21 pm to DLauw
Per Armalite and actual experience, .308 works just fine in their AR-10 which is a 7.62 rifle. I think most of the AR-10 brands/variants would be ok, but can't say for sure
Posted on 12/16/14 at 7:01 pm to Bleeding purple
quote:Dude
Try to be helpful and get a down vote?
Posted on 12/16/14 at 7:08 pm to AlxTgr
Yeah, what they said. Upvote ?
Posted on 12/16/14 at 7:56 pm to DLauw
Let me give you a simple answer:
5.56 chamber - .223 Okay
.308 chamber - 7.62x51 Okay
They are opposite of the 223/556 since the .308 can potentially be higher pressure.
But as stated by others, it isn't as cut and dry in that SOME 7.62 chambers can fire .308.
Just get a rifle in 308 and shoot both. And if shooting 223/556, get a 5.56 chamber and shoot both.
5.56 chamber - .223 Okay
.308 chamber - 7.62x51 Okay
They are opposite of the 223/556 since the .308 can potentially be higher pressure.
But as stated by others, it isn't as cut and dry in that SOME 7.62 chambers can fire .308.
Just get a rifle in 308 and shoot both. And if shooting 223/556, get a 5.56 chamber and shoot both.
Posted on 12/17/14 at 6:16 am to AlxTgr
Just trying to stir shite. Lol
Posted on 12/17/14 at 6:46 am to Bleeding purple
I'll explain in chat.
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