I need some educating.... 7.62x39 vs 300AAC

[SteveK]

I love the 7.62x36 cartridge. I have an Russian SKS and a Colt Sporter that shoots 'em well. I am of the opinion that the 7.62x39 cartridge is one of the finest whitetail rounds out there and have harvested many a deer with 7.62 over 20 or so years but, I have a recent burning question I can't find a good answer to.

Why in the hell does the 300 AAC, a round created by necking-up a 5.56x45 cartridge, shoot heavier bullets than the larger 7.62x39?

Thanks for your assistance.

Steve

[john hayslip]

Simply because we're using heavier bullets. The 7.62 is designed for gas guns and fairly low pressure ones (for gas guns) at that. The 223 runs at higher pressures. With the same weight bullet they are practically ballistic doubles.

[fryboy]

originally the 300 acc was designed as the 300 whisper ( or perhaps refinement of the 300 whisper may be a better term ) ,in order to be effective it had the need for a heavy sub-sonic projectile as the lighter ones lost energy too quick ,hence the 300 has a longer throat/leade designed for longer projectiles , the m-43 round ( 7.62x39 ) can be used with decent results with 150 grain projectiles but because of a shorter throat case capacity starts to suffer when heavier bullets protrude into the case space

[Rangefinder]

originally the 300 acc was designed as the 300 whisper ( or perhaps refinement of the 300 whisper may be a better term ) ,in order to be effective it had the need for a heavy sub-sonic projectile as the lighter ones lost energy too quick ,hence the 300 has a longer throat/leade designed for longer projectiles , the m-43 round ( 7.62x39 ) can be used with decent results with 150 grain projectiles but because of a shorter throat case capacity starts to suffer when heavier bullets protrude into the case space

^^Pretty much sums it up. BUT, I get very good results with 147gr. steel core pulls loaded over 27gr. H335 to 2.20 OAL through my MAK. Just barely fits the mag, cycles well, and great accuracy (so far). Haven't stretched the distance much, but checking POI on my 50yd back yard range was well within 'ragged-hole' results.

Compared to the 300 AAC, it's nearly the same animal. I've loaded 220gr. cast in x39 (PC'd to help minimize gas cutting from seating so darn deep), have a non-cycling load that sounds like a pellet gun, and a cycling load sitting right on the edge of sub-sonic that is about like a 22lr. It just takes a bit of playing to get the right combo for your rifle that will cycle those heavy pills and still stay below the 1050fps. line.

[Jupiter7]

I guess we also should add that 300blk was designed to run in an M4 magazine in an M4. Some of the objectives were to replace the mp5 suppressed with more power and accuracy with same manual of arms and 7.62x39 power with a barrel change only. If I was already invested in 7.62x39, 300blk would be a lateral move. The bullet weight is needed to cycle the action in an AR.

[Bullshop Junior]

It has to do with the twist. The SKS and AK rifles have a fairly slow twist. My handi Rifle singleshot has a 1/10 twist and I shoot the 200gn Lee RN in it.

[Bullshop Junior]

originally the 300 acc was designed as the 300 whisper ( or perhaps refinement of the 300 whisper may be a better term ) ,in order to be effective it had the need for a heavy sub-sonic projectile as the lighter ones lost energy too quick ,hence the 300 has a longer throat/leade designed for longer projectiles , the m-43 round ( 7.62x39 ) can be used with decent results with 150 grain projectiles but because of a shorter throat case capacity starts to suffer when heavier bullets protrude into the case space

The throat can be fixed though. My handi rifle has suck a long throat I can drop a 220gn RN jacketed in it and close a sized case behind it without it touching.

[bruce drake]

The guys have already mentioned the barrel-twist rate and the throating so I'll just say +1

I own AR uppers in 7.62x39 as well as 300BLK. Both get loaded with 125gr boolits and shoot equally well with 150gr bullets also.

I don't shoot or load the heavier subsonics in either. I consider both to be fine woods cartridges for deer or smaller game.

Bruce

[Bullshop Junior]

I don't believe is subsonic. My standard weight bullet in my 7.62x39 is a 150gn.

[HARRYMPOPE]

The 7.62 x 39 with a 1-12 twist in a custom Mauser had a .205(or so) 5 shot group record at 100 yards that stood for a number of years in the CBA with a 190+g bullet.In a bolt gun or single shot its a better choice than the 300 Whisper/AAC IMHO.The only advantage the AAC has is common magazine parts and bolt faces to the AR platform(and tacti-cool name)

[bruce drake]

Most 150gr bullets can easily be kept supersonic in the x39 cartridge with a number of powders. The 300BLK is do-able with H110 as well as AA1680 but the x39 has a better powder selection for the cartridge if you are running a gas system rifle.

Bruce

[supersniper]

Bullshop,

You might not believe in subsonics..... but they do exist. :P

Twist rates on SKS and AK is about 1 in 9.5" - which is plenty fast enough to stabilize the heavier boolits.

[Ed in North Texas]

Bullshop,

You might not believe in subsonics..... but they do exist. :P

Twist rates on SKS and AK is about 1 in 9.5" - which is plenty fast enough to stabilize the heavier boolits.

Hmmm. I think Dan is going to have to clarify. While I was wondering exactly what he thought IS not sub-sonic ( I tend to read what is written, which is not always correct), you thought he didn't believe IN sub-sonic (which would make sense, given the sentence construction). With the widespread use of spell check, we can't always tell if a thought was incomplete, or it was a typo.

Dan - please clarify which you intended.

[Bullshop Junior]

I don't use subsonic loads. I prefer about as heavy of a bullet as the cartridge will allow at the fastest speed I can reasonably make it shoot.

[supersniper]

Thanks for the clarification.

I was just teasing you a bit is all. We all have different preferences and requirements. I have always enjoyed experimenting (Research and Development).

[JeffinNZ]

There is a really good video on Youtube by a guy explaining the .300 BKL and why it came about. Can find the link sorry but it's very good.

[Artful]

This one?

https://www.youtube.com/watch?v=dxxVCWHE1Xs

[Artful]

Or maybe this one?

https://www.youtube.com/watch?v=wdOavM-Px6Y

[JeffinNZ]

Or maybe this one?

https://www.youtube.com/watch?v=wdOavM-Px6Y

Yeap, that's it. .300BLK for dummies. Really good.

[badbob454]

ill stick to my rusky sks i shoot 173 gr boolits real well , plenty of power for target shootin ... which is what i love best

[Artful]

Best thing about the 300 blackout or Whisper is the availability of components and it will work in AR platform without buying a bunch of parts to change between 223 and 300 BLK

[Bullshop Junior]

I could give a carp less about it working on the AR. Hideous, Lego guns.

7.62x39 components are pretty easy to get to and you can get brass with small or large primer pockets.

[Gunnut 45/454]

I shoot both calibers, the 300 Blk absolutely rocks ! Way more accurate then any x39 I've ever shot! That's an x39 with an actual .311 barrel not your Americanized x 39 with .308" barrel. Love my Yugo SKS ,cause I love the history of old guns, fun to shoot. If you reload your limited to just a few bullets for x39-hard to find at a decent price, cast boolits sure. With the 300 you can shoot just about EVERY .308 bullet made from 100gr on up to 240gr. And also just about any cast bullet design in .308" . So if you have a 300 blk and have no ammo you aren't reloading! I never have been, nor will I ever be out of ammo for my 300 Blk. And I don't pay more then $.09 per shot! You can't say that for your x39 cause I don't buy brass for my 300 I make it for FREE. Can you make your own brass for the x 39?:coffee::coffee:

[chrispy]

I have loaded 7.62 x 39 with cast loads for a while, two that have stood out are the 314-195gc CBE designed for the 303brit. One load uses 6gn of AS30n (red dot) which runs at 1050fps, and the second uses 17gn of AR2207, which belts along at 1700fps out of my mates 20inch barrel. My rifle is an AIA M10a2 (with the handy 10 round AK mag), and theses feed nicely out of the mag, and both hit like the hammer of Thor.
I am awaiting the delivery of some new CBE cast bullets in 220gn, again cast for the 303, just to see how they go.

Chrispy

[Artful]

I could give a carp less about it working on the AR. Hideous, Lego guns.

7.62x39 components are pretty easy to get to and you can get brass with small or large primer pockets.

Wow, Texas must have all kinds of components I'm not easily finding in Arizona

[Bullshop Junior]

Only difference is the brass. I find quite a bit. No, not as much as 223 but more then enough to supply my needs and still have a fair surplus. My rifle has a 308 barrel so if I want to shoot jacketed no big deal, but I don't shoot jacketed so even if it was 312 big deal.

[autofix4u]

I happen to be a big fan of the short Russian and find it to be well suited to heavy bullets or boolits. I have 2 ar15 in x39 one with 9.5 twist and .3095 bore. It shoots the Lee 312-185 better than any other rifle I own, with groups of .75" to 1" regularly.
The second has a 12 twist and likes 150 grn or less ran wide open with h322 or benchmark.
Also have a couple of small ring mauser in x39 one with 28" barrel and 308 bore 10 twist and the chamber cut to take up to .313 bullets. By far the most fun to shoot. Also have one with 17" threaded barrel .308 bore and 8.5 twist I have not shot yet.
Did put together a couple of 300 Bo uppers and played with them, found that anything the 300 Bo could do the x39 could do better.
Keep in mind this is just the opinion of a simple redneck.

[Fishman]

I really like the .300 blk but have been reloading for my sks without issue for the past 20 years. Those guns feed virtually any bullet design and I never had an issue with cycling. If I were planning to run my choice in an AR, I would choose the purpose built cartridge. But the 7.62 X 39 in the sks platform is a winner, it just works.

[A pause for the COZ]

The 1st day I read an article about the 300 Black out I started Jonesing for one. Not for the Sub stuff, but that is a huge +1 for the set up.
I have a huge amount of 223 cases on hand. Already had AR parts, mags on hand.
All I needed to ad was a 300 Black out upper and now have access to in my Opinion is one of the best 30 cal carbines out there.

After more than a year of having my 300 blk. I also have AK.s and SKS.
The real proof in the pudding is. What gets put in the truck to go to the range.
My 300 gets shot every time I go. Not only is it as fun to shoot as my AK I also have the benefit of looking at my targets.
And saying wow that shoots nice. I am sure some one has a AK that you can do a 20 round mag dump at each aim point at 100 yards and shoot a target like this. But none of mine will. My 300 will do it all day over and over again. And thats from a cheap made up $500 gun.

http://i33.photobucket.com/albums/d66/Kelly2215/100_8925_zps5ced62bb.jpg

What I have noticed the last year or so. The 300 Black out has no middle of the road followers. Guys that like them like them allot. Guys that dont. Dont.
Just they way it is.

[kawasakifreak77]

What I have noticed the last year or so. The 300 Black out has no middle of the road followers. Guys that like them like them allot. Guys that dont. Dont.
Just they way it is.

What he said!

I have had my blackout bolt gun a year now & am still fascinated by it. I knew about the whisper long before but being an off the shelf option now is nice. The fun stuff is the subs & getting into the NFA pool. First time I shot suppressed I knew there was no going back. Its incredible.

Experimenting with subs has taught me more than I ever knew about hand loading. Its a whole other level.

The only annoying thing to me about the blackout is trying to look up info & 9 out of 10 threads turn into an argument. If ya don't like it, cool. More ammo for me!

[Adk Mike]

Does any body have the Black Out in Hand i Rifle or a bolt gun ?

[DCP]

Does any body have the Black Out in Hand i Rifle or a bolt gun ?

Yes what would you like to know

[Adk Mike]

I was just thinking it might be a good cast shooter in a bolt gun or single shot. I have boxes of 223 and no gun. It just might be a fun project.

[DCP]

I was just thinking it might be a good cast shooter in a bolt gun or single shot. I have boxes of 223 and no gun. It just might be a fun project.

This is what I have

http://www.impactguns.com/remington-model-700-sps-tactical-300-black-out-threaded-silencer-ready-84205-047700842059.aspx

[Jupiter7]

I also have a Remington 700sps 300blk. I've shot everything in it. From 98grn .310 DEWC's over 2.5grs BE to 110gr vmax's with a case full of h110 or lil gun and of course 250grn subs and supers. In a bolt gun, powder option are secondary to accuracy and true potential of cartridge can be realized. But my 10" AR pistol is a very handy and accurate package.

[milsurpcollector1970]

I have been a bit disappointed in my 300 BO I was shooting The Lyman 314299 out of it. I had a load that did about 1600 fps with WC 820 but now that its summer that same load blows primers. I was trying to get to at least 2000 fps with a decent sized bullet. Trying to find a happy medium in the ar platform is tough. You either have light bullets that go real fast 3000 fps (223 55 gr) or heavy bullets that go real slow like the 450 bushmaster(too much recoil for me) The 6.5 Grendel J bullets are to expensive to plink with.

I have had all 3. I am thinking about the 30 HRT, larger case capacity but uses 6.8 spc style bolt and mags. I might be able to get a cast bullet up to 2000 fps now.

The 300 blk is a great concept but does it push a 150 gr boolit fast enough to kill a deer or hog? I know some folks have had good luck hunting with it but I feel like its underpowered (this is just a feeling not based on facts)

[GhostHawk]

I have not hunted with it but IMO even the 7.62x39 seems a bit on the light side for hunting.

Loaded with a heavy bullet it should do the job inside 100 yards. And frankly would probably do it better than a .243 win.

As for the .300 blackout I guess I just don't understand that whole phenomenon.

If you want to play with a .30 caliber in an AR why not the .308? That has the size, the case capacity, the speed to do the job flawlessly.

300 blackout has a place in law enforcement where you want subsonic rounds through a silencer with more penetration than a .223. Sure I get that. But if you don't have the need for silenced rounds with more penetration then why talk 300 blackout?

Just seems to me that if you want to talk hunting with an AR you should be talking .308.
I know I'm "old school" and I just don't get this whole "gadget gun" lego phase the the younger set seems to be going through.

But it seems that when you come to efficiency, you don't try to make a deer slayer out of a gopher shooter. You make it out of a system designed to do the job correctly.

300 blackout it seems to me is essentially a tool that was designed with a very specific goal in mind.
Stray far from that goal and its effectiveness drops radically.

[45 2.1]

The 300 blk is a great concept but does it push a 150 gr boolit fast enough to kill a deer or hog?

It should get an appropriate 150gr. boolit to about 2,000 fps or a little above. The best appropriate boolit works quite well in a bolt gun, but has too large a meplat to feed in an AR. These kill small game very very well and would have little problem where it was legal to use for deer or hogs. Another appropriate boolit is the 130gr. MiHec 311410 and it does do well in the AR.... velocity can go to about 2,300 fps range matching factory with excellent accuracy potential.

[GrizzLeeBear]

I'm in the process of putting together my 1st upper in 300 blackout. The things that attracted me to the cartridge are:

1. Uses standard ar parts with just a barrel change.
2. Uses easy (and cheap) to get .223 brass that is easy to convert.
3. You can drive medium weight cast bullets from readily available molds to the maximum speeds (1600 - 2000 fps) you can drive standard alloy (WW, Lyman #2, etc) boolits using standard for caliber loads.
5. I also have several thousand 150 gr. M2 fmj pulled bullets that should make good "plinking" ammo.
6. I don't have a need for subsonics myself right now, but I can easily do so if I want to. I may explore this aspect more as a way to make it cheaper to shoot (no need for gas checks) than anything else.

IMHO there is nothing wrong with, nor any great advantage to one caliber vs. another when you are comparing like calibers such as the 7.62x39 and 300 BLK. There are differences and trade offs, but many times other factors are just as important to a person. Which platform you prefer (bolt, semi, etc) or what brass, powders or bullets you have a large stock of or available to you. Sometimes a caliber can even evolve a new life that is different than what is was "designed" to do.

I'm building my 300 BLK to try out as a "short range" practice gun for Highpower Service Rifle. Our local club, like many, shoot the matches at 200 yards, using reduced targets to simulate the 300 and 600 yard portions of the match. If I can get the gun to shoot around 1 or 2 MOA with cast boolits I will be able to do a lot more practice shooting for a lot less money and extend the life of a match gun upper by only shooting it ranges with the full distances. Maybe its a fools errand or maybe it will the greatest thing since sliced bread (for me anyway).

But if the 7.62x39 floats your boat for what you want the gun to do, more power to ya!

Variety is the spice of life!

[milsurpcollector1970]

Thank you I am looking around for that mold 130gr MiHec 311410 right now. Looks like I missed out on the group buy.

[Bullshop Junior]

I have not hunted with it but IMO even the 7.62x39 seems a bit on the light side for hunting.

Loaded with a heavy bullet it should do the job inside 100 yards. And frankly would probably do it better than a .243 win.

As for the .300 blackout I guess I just don't understand that whole phenomenon.

If you want to play with a .30 caliber in an AR why not the .308? That has the size, the case capacity, the speed to do the job flawlessly.

300 blackout has a place in law enforcement where you want subsonic rounds through a silencer with more penetration than a .223. Sure I get that. But if you don't have the need for silenced rounds with more penetration then why talk 300 blackout?

Just seems to me that if you want to talk hunting with an AR you should be talking .308.
I know I'm "old school" and I just don't get this whole "gadget gun" lego phase the the younger set seems to be going through.

But it seems that when you come to efficiency, you don't try to make a deer slayer out of a gopher shooter. You make it out of a system designed to do the job correctly.

300 blackout it seems to me is essentially a tool that was designed with a very specific goal in mind.
Stray far from that goal and its effectiveness drops radically.

I've killed a few hogs with a 7.62x39. I have a NEF handi rifle single shot that I can push a 150gn bullet out of at about 2100-2200fps with out too much difficulty. About the same as a 30/30. And pretty accurate for a best around truck gun.

[Tackleberry41]

There was a write up in one of the gun magazines not long ago. Compared the 300 to the x39. Form a numbers standpoint they were the same thing. The 300 did have a very slight edge at longer range as being 308 you can get way more bullets with a better ballistic coefficient. But other than that were apples to apples.

But as some have pointed out, x39 brass is not easy to get ahold of most of the time. And in something like an AK tends to be a problem to recover it when used. Where 300 is easily made from 223. I get lots of range brass from a friend I am lucky to get 4 or 5 brass x39 cases out of a huge pile. 223 more than you know what to do with.

And as pointed out, x39 your pretty limited as to what you can shoot it out of. A few bolt guns, an H&R (if you can find one), or an AK and SKS. The x39 does not work very well in the AR platform, yes there are some who buy enough magazines to find some that work reliably, but for the most part the AR and x39 dont work together. x39 your mostly restricted to .311 barrels, yea you can go to a 308 barrel, but now cant shoot cheap stuff thru it. Where 300 all you really need is a relatively easy to change barrel, no mags or bolt to change.

I have a friend going to build one, he is going short barrel with a can, no plans to use it any other way. Thats really where the 300 becomes useful. I wouldnt buy a 300 just to go bang, bang, bang at the range. I have an SKS that will shoot much cheaper ammunition.

I went a little different direction, making my 30-30 do it. Cheaper to it seems. Only using a little over 6gr of pistol powder to get a cast 200gr out of it at the desired low velocity. Your gonna use 2x or more than 3x that much powder in a 300. I already had the rifle, piles of brass and reloading stuff.

[Artful]

I went a little different direction, making my 30-30 do it. Cheaper to it seems. Only using a little over 6gr of pistol powder to get a cast 200gr out of it at the desired low velocity. Your gonna use 2x or more than 3x that much powder in a 300. I already had the rifle, piles of brass and reloading stuff.

Hey, as long as it deliver's accurate boolit placement in all conditions, then go for it. It took me awhile to get subsonic 308's to work in the manner I wanted but when I did I was happy.

[A pause for the COZ]

IMHO.The only advantage the AAC has is common magazine parts and bolt faces to the AR platform(and tacti-cool name)

All true, plus I have a endless ( near so any way) supply of brass for the 300 BLK.

But I dont subscribe to ether or scenarios. I shoot both with equal enjoyment.