I am new to AR's and while looking at another site I came across a discussion about "you can fire a 308 in a gun chambered 7.72x51 but not the other way around"what gives.I always thought they were the same round.I shoot bolts and have just lately got my first AR.so I am not going to just call someone an idiot.Clue me in please.

http://www.thegunzone.com/30cal.html

Good site. Look around while you're there.

Thanks

Try this too:

http://www.fulton-armory.com/308.htm

BMT

OK I read the article and now I could use some help.My DPMS barrel is stamped 7.62x51.Does that mean that I cannot fire .308 ammo in it.

Nobody wants to touch this one,I dont blame them.I sure wish I had read the barrel.Or that the clerk had not called it a 308.

DPMS can't properly mark their .224 barrels so I wouldn't be surprised if they messed this up too. I would email them and ask.

A friend of mine in the industry told me they order their barrels chambered for M80. Whether that precludes the use of .308 I cannot say.

Thanks I sent an e-mail a few minutes ago.The reciever is marked 308 but that may be their model number the barrel is marked 7.62x51 so thats what I am going with.

FWIW:

Factory Black Hills 308 works JUST FINE in my DPMS AP4.

It is marketed as a 7.62 NATO Chamber (whateverthehellthatis).

BMT

E-mail from DPMS.It seems I was concerned over nothing.If the manufacturer says its safe to shoot both.308 and 7.62x51 then its safe.

the paperwork with the last Springfield M1A I bought says to shoot 7.62 NATO in it.
For the most part I do, but then I also have no problems with using .308 Federal Classic 150 grain.

You can shoot all 308 in a 7.62X51 chamber, but not the reverse some times

I'd do my research first. The chamber might be fine but heavier bullets with slower powder can screw up some semi autos as the pressure curve stays high too long and can be rough on things like a M1A op rod. Fluted chambers in HK type weapons are another issue also.

hell most makers say only factory ammo on top of it all.... Lots of that is CYA.

Anyone thats been around gas guns a bit knows there are some issues with heavier bullets and different burn rates of powder.

For what you have, if you stick between 150 and 180s in 308 you'll generally be just fine. Beyond that you are in questionable land sometimes, read up on M14 data and you'll find if you stick with known powders with certain burn curves you'll do ok with other bullets, donw to 125s and up to 210s depending.

Jeff