Should I go 300 blk or 7.62x39

[Viking350]

I have an extra lower sitting around. I wanted something with a little more punch than my 5.56, so I was thinking about buying a 300 blk upper to put on it. I looked at the price of ammo and no way I could afford to shoot it much without taking up reloading. Model 1 has 7.62x39 uppers at a real reasonable price. That would let me shoot cheaper ammo and still have a round with comparable ballistics to the 300 blk. Does anyone have any experience with the AR platform in 7.62x39?


http://www.model1sales.com/index.cfm?fuseaction=category.display&category_id=308

[FunkyPertwee]

I think reliability is a big problem with 7.62 ARs. Probably because of magazine issues, not to mention dirty steel cased ammo.

[Schuetzenman]

Funky is on target. 7.62x39 magazines are usually troublesome in the AR platform. The round just has too much taper and the stock mag well is straight having orginally been desinged for a straight walled 20 round .223 magazine.

If you want more punch then I'd suggest 6.5 grendel. Way better ballistically, less drop, wind drift and especially accuracy. Good enough for deer at least. Has the same ballistic path as 7.62 NATO at 1000 yards. Mags are available and reliable. You will need to reload if you want to shoot it much.

The .300 black out with super sonic rounds has a pretty steep trajectory, like a rainbow from what I understand and with the subsonic rounds, even worse. I really don't see it unless you plan to be some super mall ninja bad-ass sniper type.

[nfa1934]

One plus for .300 BLK is that it will cycle an AR action with subsonic ammo. That was the main selling point for me.

[L1A1Rocker]

300BLK all the way!!! Standard magazines, standard BCG, really the ONLY thing that is changed is the barrel and tube. I would highly recomend Palmetto State Armory for your upper.

The 300BLK is still a very new cartridge but it is astounding how fast the price on the ammo is coming down as more and more manufactures pick up the line. The heavy sub sonic stuff is never going to be "cheap" because of the cost of the big bullets - but you can go with cast bullets if you are not running a sealed silencer. (but that would mean reloading, du - I keep forgetting that not everyone reloads - my bad)

Here's mine in action with 245gr cast sub sonics (internally suppressed):
http://s79.photobucket.com/albums/j154/L1A1Rocker/300%20Fireball%20project/?action=view&current=HPIM0941.mp4

I grew up in a reloading houshold. Back then it was the best way to get accurate hunting ammo. When I was in collage I took up the IPSC game and bought my own reloading stuff as a cost saver - my savings paid for the Dillon SDB in about 6 months. Anyhow, after building my 300BLK I realized how expensive the big sub sonic bullets were (yeah - didn't quite think that through) so I took up casting my own.

Any how, to make a short story long, the 300BLK is a great way to get 30-30 type performance from an AR with just a 16 inch barrel. You don't have to worry about special mags, or special anything. Another issue that has been mentioned about ARs in 7.62 x 39 is cracking bolts. Apparently there is not a whole lot of meat left on the bolt when it's turned out to accept the 7.62's head diameter.

[Integratedj]

300blk for all the reasons L1A1 mentioned. There are a lot of load options if you are a reloader, and more factory loads coming out every week. the new Barnes black tips are awesome.
It just works well, and the trajectory is no worse than the 7.62x39mm. In fact many loads have much less drop off than the x39mm. It's a lot more versatile and you also don't get stuck with crappy mags and special bolts that are more prone to breakage.

[Integratedj]

Funky is on target. 7.62x39 magazines are usually troublesome in the AR platform. The round just has too much taper and the stock mag well is straight having orginally been desinged for a straight walled 20 round .223 magazine.

If you want more punch then I'd suggest 6.5 grendel. Way better ballistically, less drop, wind drift and especially accuracy. Good enough for deer at least. Has the same ballistic path as 7.62 NATO at 1000 yards. Mags are available and reliable. You will need to reload if you want to shoot it much.

The .300 black out with super sonic rounds has a pretty steep trajectory, like a rainbow from what I understand and with the subsonic rounds, even worse. I really don't see it unless you plan to be some super mall ninja bad-ass sniper type.



I used to be a huge Grendel fan boy. Then I looked at the barrel lengths they use to get their data (20-24in barrels). No one is ever going to run a barrel that long on an AR unless it is solely used for hunting or bench shooting.

[GreenhawK]

Sorry for taking this thread in a little bit of a different direction. I am looking at buying my first AR 15 soon. I have very little experience with them except for shooting a friends a few times.

I was thinking about getting one lower, and eventually having 2 uppers for it. One with a short barrel with a red dot sight, and one with a long barrel with a magnified scope for hog hunting.

This thread has me thinking about doing one with a short barrel in 5.56 and a long in 300BLK. What do you guys think about that as an option? Are you saying that I could use the same lower and the same magazines for each round?

[Viking350]

Sorry for taking this thread in a little bit of a different direction. I am looking at buying my first AR 15 soon. I have very little experience with them except for shooting a friends a few times.

I was thinking about getting one lower, and eventually having 2 uppers for it. One with a short barrel with a red dot sight, and one with a long barrel with a magnified scope for hog hunting.

This thread has me thinking about doing one with a short barrel in 5.56 and a long in 300BLK. What do you guys think about that as an option? Are you saying that I could use the same lower and the same magazines for each round?

As long as the uppers and the lower are mil spec, yes. The 300 blk uses a necked up 223/5.56 case, so magazines are interchangeable.

[nfa1934]

Sorry for taking this thread in a little bit of a different direction. I am looking at buying my first AR 15 soon. I have very little experience with them except for shooting a friends a few times.

I was thinking about getting one lower, and eventually having 2 uppers for it. One with a short barrel with a red dot sight, and one with a long barrel with a magnified scope for hog hunting.

This thread has me thinking about doing one with a short barrel in 5.56 and a long in 300BLK. What do you guys think about that as an option? Are you saying that I could use the same lower and the same magazines for each round?

I would go the opposite route, long 5.56 and short .300 BLK.

5.56 performs better in longer barrels and .300 BLK was designed for shorter barrels. Keep in mind, I'm basing that on performance of the round alone. I don't know anything about hog hunting or why you might want a heavier round in a long barrel.

And yes, you can use the same lower and magazines for both 5.56 and .300 BLK (same bolt too). The barrel is the only difference.

[GreenhawK]

My thinking on the longer barrel is for better accuracy over a longer range. My friend with the hog problem has 300+ acres of beans, so there is a chance of taking shots over 200 yds or so. I am interested in the larger round because hogs can be several hundred pounds, and I want to drop them ASAP.

[L1A1Rocker]

I would go the opposite route, long 5.56 and short .300 BLK.

5.56 performs better in longer barrels and .300 BLK was designed for shorter barrels. Keep in mind, I'm basing that on performance of the round alone. I don't know anything about hog hunting or why you might want a heavier round in a long barrel.

And yes, you can use the same lower and magazines for both 5.56 and .300 BLK (same bolt too). The barrel is the only difference.

I agree with this 100%. The 556 is NOT fun in a SBR. The muzzle blast is really extreme in a 10 inch barrel. If you want an SBR go with the 300 BLK in a 9 or 10 inch gun. The difference in accuracy between the 16 and 10 inch guns is not measurable and the drop in velocity is miniscule.

As far as shooting beyond 300 yards goes; ditch both the 300 BLK AND the 556 (especially if it's SBRed). At that point you've crossed the line into 308 territory and need to change tools.

[Integratedj]

My thinking on the longer barrel is for better accuracy over a longer range. My friend with the hog problem has 300+ acres of beans, so there is a chance of taking shots over 200 yds or so. I am interested in the larger round because hogs can be several hundred pounds, and I want to drop them ASAP.

The 300blk was designed to be an SBR cartridge, the 5.56 was not. The shorter you go with 5.56 the worse it performs. The accuracy difference between an 8-9in barrel and a 16in barrel isn't that much, especially for your intended application.
How about you go ahead and buy a liberty leonidas setup and be really happy? Hogs will hate that thing.

If it was me in your position I would buy the 8-9in 300blk upper for the hogs and for deer as well as for shits and giggles, and a 5.56 upper in 16-18in for shooting varmints with. There is a new leupold mk4 scope w bdc for super and subsonics made just for the 300blk now, and it was setup off of a 8 or 9 inch barrel. It would be perfect for the hog problem.
I bought a 16in 300blk upper and really wish I had just done a pistol build with a 9in while I waited for the SBR stamp to come back.

[GreenhawK]

Thanks for the input guys. I have been researching it pretty hard over the last several days. I also ran into the guy that owns the tactical store where I bought my last few guns the other day. He has been building several 300BLK rifles lately, and he thinks it's the greatest thing to come out in a long time.

I think that I am going to eventually go that route. I think I am going to start reloading too. The ammo seems to be pretty reasonable reloading it.