Originally Posted by GREGULON
So I am going to build a new rifle and thought at first just to build a regular ar with a 300BO barrel, but now I am wondering whether it would be better just to go .308 all the way. What are the Pros and Cons?
What is the intended use of this weapon? There is a LOT of difference between a .300 BlackOut and a .308/7.62 in several ways. Yes they both can and do run the same bullets but the 300Blk will be 200 to 400 FPS slower. The AR platforms are very (size wise) different, the .308/7.62 being a longer cartridge by far. Costs are also higher for the .308/7.62 version.
So to the Pros and Cons.
About the same cost to build as a comparable AR in .223/5.56.
All of the same hardware as the .223/5.56 with the exception of the barrel.
Hand-loads are cheaper. Brass is cut down from common .223/5.56 brass, primers are the same as .223/5.56, different powder from the .223/5.56 and generally less of it. Also different from the .308/7.62 and a lot less of it.
Less velocity/energy and the range of use is limited by this. Don't plan on shooting a thousand yards in competition.
Utilizing sub-sonic loads, the use of a suppressor could actually be useful.
Limited but growing number of listed loadings.
And now the .308/7.62 version's Pros and Cons:
Greater energy, greater velocities, greater ranges. And the associated recoil and noise.
More expensive to build/buy.
Brass is more costly and a little more powder is used in loading.
Lots of loading data.
Ammunition is available most every place.
I hope this helped a little.
I don't have an AR built for the .308/7.62 round (oh, they are generically called AR-10s) but then I do have an M1A. Kind of hard for me to justify one.
I have several ARs in .223/5.56 and one in .300 BlackOut. Again, kind of hard for me to justify any more.
The 300Blk doesn't begin to replace it's skinny brother or it big brother. They all have a nitch that they fill, at least for me. And I have no interest in SBRs or Suppressors. This old fat guy likes to tote a light handy 16in AR type about in .30 cal. The likelihood of me running into a pig as I walk my NE ridge is slim, but I would like to pop one with my BlackOut.
It all comes down to what is the intended use of this weapon?
PS. The .300 BlackOut is no longer a 'wildcat' round. It has been accepted with a SAAMI standard.