AR Calibers

[Jason27]

I was thinking of building something different with a Novekse lower I bought a while back. I was wanting to know is the 6.8 SPC the only bullet that will mag load trough an AR or is their more calibers. I like the idea of a 6.8 but it seems bullets are hard to find. Thank you for any info.

[Stickman]

Have you thought about 6.5?

[Jason27]

I did not know about the 6.5. I read that ballistically the 6.8 was a better bullet then the 5.56. Is the 6.5 a more common bullet. The 6.8 is expensive and the brass is hard to find.

[Cohibra45]

Jason,

The calibers that can be used in the AR-15 platform are only limited by the OAL to be able to fit in the mag well. Check out these links:

http://www.ar15.com/forums/forum.html?b=3&f=121

That is the first link that will answer most of your questions as it is from TOS better known as Arfcom. Just realize that there are some very strong willed people that support either the 6.5 or 6.8. Both of these calibers are what are considered intermediate cartridges and are both very good for hunting/target out to 600yds then the 6.5 should perform better on past to the magical 1000yds....That said, most everyone can't shoot that far, they just like to have the ability to say that their rifle can do it. Remember, both will shoot that far, just the 6.8 will be traveling slower and have a larger drop to compensate for.

Now for other calibers, there is a smaller one being the 204 Ruger and a host of larger calibers starting with the 7.62x39 going up to things like 50 Beowulf and 458 SOCOM. People will have strong opinions about the 7.62x39 also, but to date, the main problem is with magazines that work most of the time (which I have read that most don't). YMMV!!! The other two links that I am about to give are for the 6.5G and 6.8 SPC forums. Both of these are great sites and have loads of information on each. They both require joining, but that is mainly to keep out the spammers/porn people!!!

http://www.65grendel.com/

http://www.68forums.com/

All I can offer is, read, read, and then read some more!!!!!!! Ask all the questions you want and make your own decision, after all, it's your rifle/money!!!

Kelly (Cohibra45)

[Jason27]

Thank you!!!! Great post.

[urikagold]

Do you have to have a special lower to build a 6.8 or will a 5.56 lower work?

[Cohibra45]

Do you have to have a special lower to build a 6.8 or will a 5.56 lower work?

All the calibers I mentioned above will work in an AR-15 lower. All that is needed is different barrel (of course), different bolt to fit the case head (which will work with most any BCG), and caliber specific magazines. Most people will buy a complete upper to make changing between calibers easier. It would also be easier to color code your magazines as all will fit in the AR lower!!!

Take care,

Kelly (Cohibra45)

[Stickman]

I did not know about the 6.5. I read that ballistically the 6.8 was a better bullet then the 5.56. Is the 6.5 a more common bullet. The 6.8 is expensive and the brass is hard to find.

The most easy to find alternate calibers for the AR15 are going to .22 and 9mm. After that, the 6.8 is one of the more common calibers available, which is worth keeping in mind if you decide to go with an alt cal.

I know a couple guys who have 6.8s that never get shot because of ammo prices and availability.