Please help me understand ammo sizes.

[TonyInVa]

I have been lookins at purchasing an AR-15. I do not understand the difference between all the ammo types. If someone could explain it to me I would appreciate it. A link to a good chart would be better. I looked on google but could not find one that had .308, .226, .223 and all the other ammo types. I chould also explain that I some what understand the difference in bullet size but if someone could also explain the benefites of each projectile, such as things like velocity and penetration.

[RugerJoe]

I'm certainly no expert here, but I'll make an attempt. The AR-15 was originally developed to shoot the 5.56\.223 rifle cartridge.

Wiki has a good write up on the AR-15 generally.

http://en.wikipedia.org/wiki/AR-15

You often see 5.56 and .223 used interchangeably because many rifles will shoot both. Some should not be loaded with 5.56. You didn't ask about this in your post, but chances are you will end up wondering about it while Ar-15 shopping. I sure did. I suggest reading this for a good explanation of the 5.56\.223 differences:

http://www.ar15armory.com/forums/556-22 ... 22582.html

More detail on 5.56

http://en.wikipedia.org/wiki/5.56%C3%9745mm_NATO

As far as Ar-15 rifles available in other calibers, well, they all have their advantages and disadvantages I guess. Ammo price, power, penetration, recoil, etc will all be different.

[Rich]

You could look at the ballistics charts for some of the ammo manufacturers. As far as bullet weights for a particular caliber...that is a matter of huge debate.

[biggun]

My apologies for not sticking to the op original question and am off topic.
The endless versatility and combinations will keep you busy. I too could not decide what to do. May I suggest a good book by Walt Kuleck with Scott Duff, " The AR-15 Complete Owner"s Guide". They also have a good complete assembly guide that I used in combination with AR15.com wed site. I decided to determin "what my ar's purpose in life would be" ie: short range / close quarter, long range, varmit, hunting and so forth. Then when you change your mind or have a fancy for something else, buy a new upper to switch out to a diff. caliber. The offerings are almost endless, bet you cant have just one!

[Reca]

You often see 5.56 and .223 used interchangeably because many rifles will shoot both. Some should not be loaded with 5.56. You didn't ask about this in your post, but chances are you will end up wondering about it while Ar-15 shopping. I sure did. I suggest reading this for a good explanation of the 5.56\.223 differences.

I hope this will help out in reference to that

"Well, in short yeah you can. Are there issues with it, well maybe so..... Will it blow your gun aparts and send pieces of the gun thru your brain housine group, probably not. But lets take a look at what the issues are for reals.

First of all there are three major types of AR chambers. The .223 SAMMI, the .223 Wylde and the 5.56 NATO. It's all so crazy and convolutted that we will skip right to the point of it all and look at it in laymans terms.

The real issues are the case neck, freebore length, throat angle and headspace. Now what do they each mean?

Case neck- Thats where the bullet sits in the case.

Freebore length- Thats the length between cases end and where the lands and groove start. This is where the bullet is actually free in the bore when it leaves the case. This affects the pressure of the round as the lands and grooves cause pressure to build behind the bullet.

Throat angle- This is the angle of slope where the freebore ends and transitions into the lands and grooves.

Headspace- This is the depth of the chamber

Now the headspace on all chambers is the same at 1.4636, so that is a non issue. The throat angle is significantly different though, 3 degrees for the SAMMI and 1.25 degrees for the other two. How does this affect you? It makes the pressure in the SAMMI start quicker as pressure is appled more abruptly.

Freebore length is a big issue in the three. The freebore for the SAMMI is a mear .025, the Wylde is .062 and the 5.56 NATO is .057. What does that mean? It means that the SAMMI builds pressure a lot faster than the Wylde or NATO chambers. Add this to the fact that NATO rounds are already a few hundred feet per second faster and as much as 5,000 PSI higher in pressure and you have an issue building rapidly. As is the pressure.

Does this mean that your gun is going to explode by using NATO ammo in your .223, probably not. They are massively over engineered and generally pretty safe for these kinds of things. They are designed to take pressure spikes, however I DO NOT RECOMMEND IT. It simply is not safe. You WILL probably start to see primers popped out of the cases or swollen.

So what do we do about it all? Well, we try to order all of our AR's in the 5.56 chambers. That allows you to shoot whatever you want to in the gun. The next thing you can do is shoot .223 ammo in your guns. Milsurp is not as cheap as it used to be, so there is not much advantage to go that route anymore. But if you do find a deal having a 5.56 chamber is going to make life more comfortable for you. But if you dont have a 5.56 chamber, just dont shoot milsurp ammo."

Found at
http://wethearmed.com/rifles/can-you-sh ... ice-versa/

As far as choosing the right Cal. for you. That depends on a lot of things. I would strongly recommend you take some time to read section 4 on this site.

http://ammo.ar15.com/project/Self_Defen ... AMMUNITION

I personally have a 5.56/.223 upper as well as a 6.8 spcII

[TonyInVa]

Thanks for all the info. It is all usefull. The common question it seems with most guns one buys is "what do you want to do with it" determins what caliber you should purchase.

[Rich]

Thanks for all the info. It is all usefull. The common question it seems with most guns one buys is "what do you want to do with it" determins what caliber you should purchase.

Thats true...but I have owned and love some firearms that most would view as having little use. Some guns are just plain fun even if they are not practical. Just sayin