AR Upper build - 7.63x39 or 300BLK???

[Katana]

Ok, so I've got two AR upper builds in the works. I was thinking of going with the 7.62 as there is plenty of cheap ammo but after looking around I see that the 300BLK is very popular. So wht are the pros and cons to both of these??

Forgive me if this has been beatin to death but after 5 pages in the black rifle forum I didn't see any other threads talkin about this.

 

[Power Pill]

Do you reload? 300blk isnt the cheapest or easiest ammo to come by

 

[Dr.K]

A major advantage for 300 blackout which is often overlooked is the ability to shoot in indoor ranges. I can't shoot rifle Calibres at my range so .556 is pretty much useless to me. A 220 gr bullet out of a 9-11 inch AR is only going to fly at about 1000-1300 fps (10mm power) which is well within the range of most indoor clubs. If your at an outdoor range this is probably not an issue. I'm dying for an AR but .300 blackout is one of the only Calibres avail to me at the moment.

 

[lanis]

Once you have built your AR, you will need ammunition for it.

Ask yourself what is easier to find and less expensive to purchase?

 

[Katana]

I do reload so that would be my best bet for ammo for a 300 but 7.62x39 is way cheaper so...

 

[Stevebot-7]

Well, positives for 300 BLK: You can form it from the .223 brass that you already use. As well, you can use your same .223 magazines for it, and can retain and use your bolt carrier group for it, there is a very large selection of .308 bullets that can be used.
Negatives are: Fairly expensive and/or time consuming to get ammo, need to buy new barrel.


For 7.62x39, positives are: Cheap surplus ammo.
Negatives are: You will need to buy new magazines, a new barrel, a new bolt carrier group, and some ranges have been cracking down heavily on steel core and other surplus ammo.

So, I would recommend adding up the prices of new magazines, new barrel, new BCG for 7.62x39 and compare that to the overall price of 300BLK. It may actually be cheaper to shoot 300BLK because you don't need to buy so much other stuff to actually shoot it. It'll be easy to swap out your BCG and charging handle from your .223 upper to your 300BLK one, and that can potentially save you the cost of a crate of surplus ammo right there.

Edit: This all relies upon the idea that you already have a .223 AR. If you don't, then do a costs comparison of x39 compared to 300BLK to determine which one will actually be more expensive.

 

[cr5]

300BLK without a doubt.
7.62x39 is for red rifles. It feeds like crap from an AR mag (less noticeable with 5 round mags but it's not an ideal setup). You are also limited to about 3 choices of ammunition for it.
Brass for 300BLK is easy to make and there are a thousand choices for projectiles. You can load 110gr supersonic all the way up to 220gr subsonic and everything in between. It's pretty cheap to reload for 300BLK as well if you use bulk 30 cal projectiles and a pound of powder goes a long way when you are using less than 20gr per round. 300BLK is also easy on brass, I have some on it's 5th loading and it still looks like it did on it's first when I pull it out of the tumbler.
I now have three 300BLK rifles and they are all accurate and fun to shoot.
If you ever get tired of it you can always convert your rifle back to 223 for the cost of a barrel then sell your 300BLK barrel and equipment to pay for the 223 barrel.

 

[hbean]

All depends on how much you shoot?

if you already own reloading equipment, it will help a bit, you are looking at 30 cents a round for 300BLK vs 22 cents for surplus ammo. if you are starting from scratch than it will take lot of cases of ammo before you recoup the initial cost of starting out.