I just bought a 9mm, and have seen 9mm luger and 9mm NATO.  What is the difference.  And do different grains have a large effect on pistols.  ive seen 115g 9mm to 147g 9mm.  I have an ar and know the different grains are for different twist.  Thanks in advance for help or pointing me in the right direction.

A 9mm NATO round is a 124g FMJ bullet with a specific amount of powder behind it. There is a milspec for it and you can read about it on the web.

Everthing else is just 9mm "Luger" because Luger invented the round, but I've seen anything from 95g to 147g and there's +P and +P+ that specify how much powder pushes it out the barrel.

You have to read the manual for your pistol and make sure you use the ammo it recommends.

Just don't buy 9mm Markov, it's a different bullet all together.

Many rounds have multiple names.

9 mm Luger = 9x19mm = 9mm Parabellum

Also often called 9mm NATO, but technically 9mm NATO is 9x19mm ammo which has been manufactured to specific NATO specifications and STANAGs.

9mm NATO ammo is +p, so as long as you are shooting a modern and well-made pistol, you will have no problems. If anything, check your pistol's manual on recommendations about shooting 9mm NATO.

 

Actually it's not.

SAAMI 9mm +p and NATO are different pressure specifications.  It's higher than standard 9mm but not as hot as +P.

Maximum pressure specs:
C.I.P 9mm = 34,083 PSI  (235 Mega-Pascals)
SAAMI 9mm = 35,000 PSI  
SAAMI 9mm +P = 38,500 PSI  
NATO 9mm = 36,550 PSI

I shoot it all out of my G17, & M9. The NATO does have a little more kick.

Which pistol, OP?

SAAMI and the military use two different methods of measuring pressure, so the two are not  directly comparable.

Contrary to the nonsense posted here and on other websites as well, there is nothing at all “hot” about the 9mm 124 grain NATO load.  The velocity figures that people like to throw around for the 9mm 124 grain NATO round are from test barrels, (7.85” EPVAT barrels to be specific) not actual pistol barrels.  Even when fired from a Beretta 92, with its 5 inch barrel, the 124 grain NATO round doesn’t even come close to the velocities people claim.  In fact, there is little difference in velocity between the 9mm 124 grain NATO round and a modern standard pressure 9mm 124 grain hollow point round.

As an example, the chronograph printout shown below is from the Speer 124 grain Gold Dot (standard pressure load) fired from a Beretta 92.  The instrumental velocity at 21 feet is 1114 fps.





Now take a look at the next chronograph printout.  This printout is from the Winchester 9mm 124 grain NATO load fired from the same Beretta 92, fired immediately after the Gold Dot load was fired.  The instrumental velocity at 21 feet is 1108 fps; 6 fps less than the Gold Dot load.





Here is some additional chronograph data, this time comparing Federal's 9mm 124 grain NATO load to several other 124 grain duty loads. All loads were fired from a SIG Sauer P229 with a 3.8" barrel.  Note that the 9mm NATO load is the slowest load in the table.