5.56 vs .300blk

[knight0334]

Realistically here in PA with the terrain, if SHTF and Red Dawn happens, would most people end up in a gunfight over 150 yards or under?

Most of your man on man fighting even in wide open areas is that range or less, most engagements beyond that are via equipment(planes, APC, tanks, etc). Most firefights beyond that rely on volley or high rate of fire to raise the hit probability. A SHTF/RD thing would like have most fighting within urban areas.

Most of your deer are probably take well less than 200yrds.

[MMH]

I'm working on a load with 110g Nosler Varmageddons and on my first powder charge already got up 2300 FPS. By the time I am done I'll be on par with any intermediate 30 cal rifle cartridge out there. I put some of these rounds on my steel gong and was damn that hits hard. If you want energy and velocity I think 110g is where it is at. Not 125g.

I have worked up 110 gr. (Hornady GMX) loads and gotten 2460 FPS (1477 ft-lbs). That is hitting hard! I was beginning to see some pressure signs, but nothing crazy (primers just beginning to get flat, slight ejector drag marks, etc.). Not excessive, but I back off to get better brass life. So you are correct, if max energy/velocity is your goal, lighter bullets will do better.

Long term, I am going to cut down the barrel. I plan on cutting it down one or two inches at a time, shoot my max loads (already developed for 16" barrel) for all bullet weight from 110 gr. up to 250 gr. chonographing all shots. Probably end up with 10" barrel. My guess is that the lighter bullets will perform almost as well with a 10" barrel as a 16" and I do not want to give up too much supersonic performance, which is one of the great characteristics of the 300 BLK cartridge. In any event, will have good data on impact of reducing barrel lengths for the 300 BLK. The ultimate objective is to have a suppressed rifle w/ total size of a m4.

[wanneroo]

I have worked up 110 gr. (Hornady GMX) loads and gotten 2460 FPS (1477 ft-lbs). That is hitting hard! I was beginning to see some pressure signs, but nothing crazy (primers just beginning to get flat, slight ejector drag marks, etc.). Not excessive, but I back off to get better brass life. So you are correct, if max energy/velocity is your goal, lighter bullets will do better.

Long term, I am going to cut down the barrel. I plan on cutting it down one or two inches at a time, shoot my max loads (already developed for 16" barrel) for all bullet weight from 110 gr. up to 250 gr. chonographing all shots. Probably end up with 10" barrel. My guess is that the lighter bullets will perform almost as well with a 10" barrel as a 16" and I do not want to give up too much supersonic performance, which is one of the great characteristics of the 300 BLK cartridge. In any event, will have good data on impact of reducing barrel lengths for the 300 BLK. The ultimate objective is to have a suppressed rifle w/ total size of a m4.

Yes I think I can easily reach 2400 FPS and man even where I am now I've never seen a 300 BO round hit my steel so hard. I am using Lil Gun powder but have not loaded 110g before so there will be some experimenting. Hopefully that powder works as I have 4 pounds of it. I could also try IMR 4227 as I have a pound of it and I have a small quantity of H110. I have not shopped in a gun store for a while so I am guessing powder supplies are short. Also have some CFE BLK but did not find that suited to supersonic 300 BO.

[wanneroo]

Most of your man on man fighting even in wide open areas is that range or less, most engagements beyond that are via equipment(planes, APC, tanks, etc). Most firefights beyond that rely on volley or high rate of fire to raise the hit probability. A SHTF/RD thing would like have most fighting within urban areas.

Most of your deer are probably take well less than 200yrds.

That's why I think 300 BO is pretty well suited in terms of what you get in the overall package. I guess people can split hairs and say well 7.62x39 is about the same, or they like 6.5 Grendel or 6.8 SPC or even 6 ARC and I say cool.

I'm not a current fan of 5.56, but I think with the right bullet it's very effective.

[MMH]

Yes I think I can easily reach 2400 FPS and man even where I am now I've never seen a 300 BO round hit my steel so hard. I am using Lil Gun powder but have not loaded 110g before so there will be some experimenting. Hopefully that powder works as I have 4 pounds of it. I could also try IMR 4227 as I have a pound of it and I have a small quantity of H110. I have not shopped in a gun store for a while so I am guessing powder supplies are short. Also have some CFE BLK but did not find that suited to supersonic 300 BO.

I've had great results w/ H110 for lighter bullets & AA1680 for the heavier ones. Looking at the SierraPowder Burn Rate chart, here are the rankings of powders from fastest to slowest:

51 Lil'Gun
53 H110
57 IMR 4227
61 AA1680
62 CFE BLK

There are 150 powders so all of these are all close to the same burn rate. Lil'Gun is just a little faster than H110 and I would expect it to do well. CFE BLK would be better for your heavier bullets. You could use it for the lighter ones, but I would not expect the same velocity that you will get with the faster powders.

Good luck & be careful!

[DukeConnor]

Yes I think I can easily reach 2400 FPS and man even where I am now I've never seen a 300 BO round hit my steel so hard. I am using Lil Gun powder but have not loaded 110g before so there will be some experimenting. Hopefully that powder works as I have 4 pounds of it. I could also try IMR 4227 as I have a pound of it and I have a small quantity of H110. I have not shopped in a gun store for a while so I am guessing powder supplies are short. Also have some CFE BLK but did not find that suited to supersonic 300 BO.

After trying a variety of powders I settled on IMR4227 for both supers and subs. lil gun would get the can smoking hot real fast.

[MMH]

After trying a variety of powders I settled on IMR4227 for both supers and subs. lil gun would get the can smoking hot real fast.

Why? I have not tried 4227 but have settled in on H110 for light bullets.

[DavidH]

I can load 69gr HPBT*s to 2850fps. That puts energy approaching 1350lbs....within 130lbs or so of that 110gr 300aac load. (I mean, if you count muzzle energy for something..which I don*t). But that 223 load will also have superior Sectional Density and will put range the 110gr load by a large margin. I*m still trying to figure out the gain? Unless you want to be quit & all with your Tripple S! (super assassin silencer) But now we are talking heavier bullets and much less velocity.

[MMH]

I can load 69gr HPBT*s to 2850fps. That puts energy approaching 1350lbs....within 130lbs or so of that 110gr 300aac load. (I mean, if you count muzzle energy for something..which I don*t). But that 223 load will also have superior Sectional Density and will put range the 110gr load by a large margin. I*m still trying to figure out the gain? Unless you want to be quit & all with your Tripple S! (super assassin silencer) But now we are talking heavier bullets and much less velocity.

You are not getting 2850 out of a 16" barrel - definitely need a 20". With the 300 AAC I'll bet that you can get 2300 fps with a 12" barrel and not even need a 16". Lets not compare long range precision rifles to a suppressed CQB rifle. If you want to take things out of context lets compare a 5.56 to a 6.5 Creedmore.

What does the sectional density do for you? Lets keep it simple & talk about ballistic coefficient and then compare downrange retained velocity, drop, etc. I did a fairly detailed comparison of a 125 gr. 300 BLK comparing it to a 55 gr. 5.56 earlier in this thread.

[Tacgunner]

The most "fair" comparison would be two uppers, one in 300 BO, the other in 5.56. Both with 16" barrels and same optics. Ammo would be standard supersonic off-the-shelf ammo. Most folks would want to see these compared for defense/hunting uses.

After that, the discussion can go to sub-sonics and suppressors, or long-range challenge type stuff. Handloads are a subclass of the discussion as not everyone reloads (just trying to be fair). The 7.62x39mm comparison works best when talking reloaded 300 BO versus factory 7.62x39mm (what you can get outta 300 BO if not using factory 7.62x39mm). Plus, if there is no 7.62x39mm, you can always make 300 BO from .223/5.56mm brass (again, a reloading issue).