300 blk or 7.62x40 wt?

The .300 BLK puts out some very nice hunting loads for anything up to deer. Its performance over 300 yards though is iffy and it definitely shines in the sub-200 yard area. Ammo is becoming more and more popular too, so if you just want to plink it doesn't cost you a couple internal organs.


On the other hand, I have seriously never even heard of the 7.62x40, and a quick search says have fun getting ammo for it!

Why those 2?

i'll take 6.8 spc

Whats wrong with an x39 upper?

tyeo098 said:

Whats wrong with an x39 upper?

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x39 requires new magazines, which have a 50/50 track record. .300 uses the same bolt and mags, which is a biggie in the convenience department...

So you trade convienience in bolt/mag combo for expensive and hard to find ammo?

Personally I'd rather have a 545x39 upper. Uses 223 mags as well.

Purpose!
Supersonic Mostly: 7.62x40WT
Subsonic Mostly: BLK.

tyeo098 said:

So you trade convienience in bolt/mag combo for expensive and hard to find ammo?

Personally I'd rather have a 545x39 upper. Uses 223 mags as well.

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Well plinking ammo is going for $11/box, which is hardly expensive, and there are currently at least a dozen different types of ammo going for it, which in my book is not "hard to find." Heck, even my local gun store stocks it!

5.45 is nice, but way to close to the .223 to make it worth buying, and it's not really in the field that the OP is looking for (.30 caliber/more powerful than what he has).

The nice thing about the .300 BLK is that you only need a new upper ($300 w/o bolt) and ammo. The magazines and bolt are shared, and puts out better power than a normal .223 without the recoil of a .308. The 6.8, 6.5, 7.62x39, and 5.45x39 do not offer this simplicity for such a relatively little amount of money.

Your LGS stocks 762x40WT? - thats the round I was talking about. Not 300BLK

I've never even heard of it before until today. Odd.

I personally would pay for a different bolt and magazines once vs paying top dollar for ammo over and over and over and over and over again. Then again this isn't our choice of what we would pick other than the two listed. Let's not judge the op for their choice in calibers. If I had to pick between the two I would definitely choose x40 simply for the extra power. And I would reload for it as often as I could afford to and keep stocked up on both subsonic and supersonic ammo. To take advantage of this round I would also go ahead and take the dive for a suppressor. Because other than that there is really no point to either of these rounds while the 6.5 grendel, 6.8 spc, and 7.62x39 have all been around long enough to be established with multitudes of shooters.

tyeo098 said:

Your LGS stocks 762x40WT? - thats the round I was talking about. Not 300BLK

I've never even heard of it before until today. Odd.

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My bad, I was talking about the .300 BLK.

Someone is posting a simple question of BLk vs 7.62x42 and gets 1000 different other options.
Why it is so hard to stay with those and with the OP on topic?
We love the AR's like legos. It is not about what caliber, it is a wildcat revolution. People are not selling just cartridges they are selling experiences, dreams, projects, ...just like Steve Jobs! LOL!.
Also to the 308 defense what in one has a lifetime supply of 223rem brass like I do, furthermore what about a lifetime supply of 308 surplus bullets? This is a very inexpensive way to go, maybe even cheaper than the .223 if you already have some of those old surplus deals. Both are nice and the x42 gets the edge. Whatever it is, if it shoots and is accurate and cheap it has a role.
I wished folks would not start the AR caliber options tango every time someone asks a simple question.

"Mine is better because it is a bigga bullet".

7.62x40 squeezes out maybe 100fps or so extra over 300BLK based on Wilson's numbers. Not a lot. I would only get it if you are a dedicated reloader and are ready to make brass for it from .223 cases.

300BLK has and will have a lot more support. 6.8 SPC or 6.5 Grendel ekes out somewhat more performance than either 300BLK or 7.62x40 if you're looking for the greatest possible performance in an AR15.

I am looking for performance and availability.

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The WT offers a slight performance advantage on paper. The BLK is far more available, and far more supported. Neither even come close to .308 performance, but the point is getting 30 cal in an AR-15 right? Right now I'd go with the BLK because it's basically become an industry standard within a year of introduction.