.300BLK Comparison Thread

[jblomenberg16]

I've had a big gulp of the .300BLK and love it. But there is a lot of debate still on going about the practicality of this cartridge. Yeah, it is cool to have a .30 caliber bullet that shoots out of an AR15 platform with no special modifications other than a barrel chambered for .300BLK, but is it really worth it?

I hope to provide some data to help you make that decision for yourself, since in the end we all have our own purposes for our rifles and our ammunition. I hope this thread takes a little of the emotion out of the debate and provides some factual data to help you make an informed decision.


I hope to try several different tests of "practicality" at the range over the comming year. Right now my rifle is a 16" upper, but will eventually be converted to a suppressed SBR once all of the necessary paperwork from Uncle Sam come back. If you have any suggestions, please post them up and if it is feasible for me to attempt, I'll do my best to do it.


The next post will be the first of hopefully several practical comparisons.

 

[jblomenberg16]

Part 1: .300BLK vs. 7.62x39 vs. .223- Basic Ballistics

Much of the debate right now about the .300BLK is whether or not it offers any real advantages over the tried and true 7.62x39.

Today I did some basic ballistics comparisons between the 7.62x39, the .300BLK, and .223 (5.56 Nato) for comparison. The test rifles were my WASR10-63 underfolder, a true no-frills entry AK pattern rifle, not unlike the one you may have in your safe. The .300BLK is a factory CMMG 16" upper, and the .223 is a factory S&W M&P15 upper that has been fitted with a troy free float handguard.

All tests today were with iron sights at 50yds, from a very simple range bag rest. I chose 50yds for a couple reasons.

1) That is the approximate zero range for my AR's (I've attempted the RIBZ zero with them that gives a 50yd / 200m zero). I was unsure of the zero on the AK as I hadn't shot it in a while, but knew it would be on the paper at 50 using the battle zero setting on the rear leaf.

2) It was easier to make sure I had good alignment with the chrony at that range.

3) If a rifle and or shooter doesn't shoot well at 50, it is going to shoot even worse at 100. I wanted to have shots on paper today that were easy to compare and gave me the best chance of success.

The weather was Sunny and about 50deg F. Didn't get a barometer reading, but then again this isn't intended to duplicate a lab condition either.


Test Subjects - Rifles:

Test Subjects - Ammo:

123gr. 7x62x39 "Golden Tiger"
.300 BLK hand loads, pulled 147gr FMJBT bullets over 17.0gr H110 powder
.223 hand loads, 55gr FMJBT bullets over 25.3gr H335. *** Note that is a pretty hot load...I am trying to get close to 5.56 M193.


Test Results:

7.62x39

Looks like I may need to re-run with the rear sight at the 100yd or even 200yd setting. The battle zero appears to have held true in that it was about 6" high at 50yds, which should put it pretty much back on again at 300yds. Note that the numbers are just a tally to make sure I had 10 hits, not in order I shot them. At some point I must have compensated and brought the bottom 3 down a bit.

Not a group to write home about by any means. The AK's rear leaf sight makes precise aiming tricky, especially if you've grown used to the peep arrangment on US battle rifles. The underfolder stock also makes a consistent cheekweld and sight picture a little tougher. I'm not going to blame all of the accuracy problems on the gun, as the guy pulling the trigger has a lot to do with it as well. With a little practice with the gun, I could probably cut that group in half.

For the 10 shot group I got an average velocity of 2320 FPS, with a standard deviation of 14.5 FPS. Not too bad for factory ammo, and about on Par with expected performance of 2400FPS in standard conditions.

Using some basic calculations from ballistics software, the 7.62x39 would have the following energy out to 300yds. ***Note, my calculator did not have a FMJ bullet in .311, so I used a .311 SP hunting bullet as a reference BC. That can and will make a difference in down range velocity.

Range - Energy (foot*lbs)
0 - 1494
50 - 1315
100 - 1153
150 - 1006
200 - 876
250 - 762
300 - 660


.300BLK

I'm still working on load development, but have quickly settled on 17.0 grains of H110 as a nice safe plinking load. There isn't much data out there yet for the 147gr bullet, but there are folks loading a bit hotter and pushing it a little faster.

The group wasn't too bad, but still nothing I'd hang on the refrigerator and brag about. Right at a 3" group, centered about 2" high. I might need to make an adjustment to the front sight as I have been shooting a bit high. It was better than the AK with the 7.62x39, but won't win any matches. Once again the shooter will take the blame for that. The rear peep sight helped me, but didn't get me all the way there.

Using the 10 shot group, I had an average velocity of 1950FPS, with a standard deviation of 11.4 FPS. I was pretty happy with those results, and probably will stick with this load as a plinker.

I used the same ballistics software as above and used a BC from a similar hornady 150Gr FMJBT bullet for down range performance. Again, that can affect results slightly.

Range - Energy (foot*lbs)
0 - 1241
50 - 1129
100 - 1026
150 - 1932
200 - 846
250 - 766
300 - 694

From zero to 200 is is less energy, then about the same between 200 and 300. The difference there comes from the better BC used in the comparisons, meaning that 147gr didn't lose velocity as fast as the 123gr did on the 7.62x39.


.223

I wanted to get some good data from a load that I worked up as a "Clone" of M193. Looks like I'm fairly close, but need to run through my 20" barrel to confirm.

Best Group of the three, and getting closer to something I'd be happy to post on the internet. Vertical spread was about 1.5", but left to right was still in the 3" range. Looks like my rest and my technique need to be improved if I want to have a very nice group.

Average velocity for this string was 2985FPS, which is pretty good out of a 16" barrel. Std Dev. was pretty high though at 32. I had one low velocity down close to 2900 that really skewed it. Need to check the consistency of my charges.

Energy for the .223 is as follows:

Range - Energy (foot*lbs)
0 - 1088
50 - 956
100 - 837
150 - 730
200 - 634
250 - 548
300 - 471



For those of you engineers that want to see the data side by side, here it is for all 3.

Conclusions:

• In my very limited test, the AK did prove to be a little less accurate than the AR platform. I will credit both AR's used in this test advantages in rear sight (Peep) and better ergonomics (consistent sight picture).
• The 7.62x39 does have more energy at ranges less than 200yds than the .300BLK. Simplified, energy is 1/2 * mass * velocity^2, so even though the bullet was lighter, the velocity was enough to overcome the .300BLK.
• The .300BLK does offer a clear increase in muzzle energy over the .223, which is one of the big draws to this caliber at the moment.

 

[paddling_man]

Might want to check that .300BLK at 150 on the side-by-side. 1932 sounds like the result of an inertial accelerator.

 

[jblomenberg16]

Might want to check that .300BLK at 150 on the side-by-side. 1932 sounds like the result of an inertial accelerator.

Oops! You are right...you caught my magic trick. Should be 932. That, or my secret rocket powered exploding boolits!

 

[paddling_man]

Here I was thinking, WHOA, 150 is the SWEET SPOT! Rock on, Garth.

 

[in812]

tag pm sent

 

[Broom_jm]

So, bottom line, this cartridge runs clean from a standard AR mag, but when comparing apples-to-apples, lags behind the 7.62x39 at every turn? It has a lot of advantages, but if I was going to spend this kind of money for a 30 caliber AR, I think I'd go all out and pick up the 30 Remington AR. You give up magazine capacity, but get a whole lot more performance downrange.

The 300BLK is basically a standardized 300 Whisper...which isn't a bad thing!

 

[jblomenberg16]

So, bottom line, this cartridge runs clean from a standard AR mag, but when comparing apples-to-apples, lags behind the 7.62x39 at every turn? It has a lot of advantages, but if I was going to spend this kind of money for a 30 caliber AR, I think I'd go all out and pick up the 30 Remington AR. You give up magazine capacity, but get a whole lot more performance downrange.

The 300BLK is basically a standardized 300 Whisper...which isn't a bad thing!

A 30 Rem AR is definitely going to surpass the 7.62x39 and put you in the .308win range of performance. 7.62x40 WT will more than likely get you closer to 7.62x39 performance.

I think that as the testing move along it will show that the .300BLK was optimized for subsonic suppressed operation with a long heavy .30 cal bullet, so sacrifices a bit of performance at range. However, it is still putting more energy down range than the .223.

 

[gunbunnies]

Just thought I would put my toe in the water here and add that I understood from what I have read on the 300 BLK / 300 Whisper that the 300 BLK was built up around the 125 Gr. bullet class and in that weight it would come out of the barrel at a higher velocity, changing your overall statistics a bit in looking at the cartridge performance. The heavier bullets in the 30 class out of this cartridge is the 300 Whisper which was designed to be subsonic and made for the suppressor in it's design, pushing a very accurate and proven bullet class at a very low velocity. Now, just my concept on the caliber and it's design, but to really test these calibers against each other you need to decide if your testing the 300 BLK or the 300 Whisper... Just my .02 cents worth...

 

[jblomenberg16]

Just thought I would put my toe in the water here and add that I understood from what I have read on the 300 BLK / 300 Whisper that the 300 BLK was built up around the 125 Gr. bullet class and in that weight it would come out of the barrel at a higher velocity, changing your overall statistics a bit in looking at the cartridge performance. The heavier bullets in the 30 class out of this cartridge is the 300 Whisper which was designed to be subsonic and made for the suppressor in it's design, pushing a very accurate and proven bullet class at a very low velocity. Now, just my concept on the caliber and it's design, but to really test these calibers against each other you need to decide if your testing the 300 BLK or the 300 Whisper... Just my .02 cents worth...

Great points. I do intend to do some testing with some lighter .30 caliber bullets. Thus far I have run some 125gr. Noslers to about 2250 FPS, so nearly the same velocity as the 7.62x39, meaning similar energy.

The overall goal of the comparison is to focus on the .300BLK in both super sonic an subsonic form.

 

[U.S. Patriot]

Now it's making me want a 300 upper. I would most definitely hand load.

 

[Broom_jm]

Great points. I do intend to do some testing with some lighter .30 caliber bullets. Thus far I have run some 125gr. Noslers to about 2250 FPS, so nearly the same velocity as the 7.62x39, meaning similar energy.

The overall goal of the comparison is to focus on the .300BLK in both super sonic an subsonic form.

To stay within the OAL limitations, and not impinge too greatly on powder space, are you best off with a round nose bullet or is it optimized for sharply pointed bullets?

I handload 125 Nosler Ballistic Tips with "Youth" loads of H4895 out of a 30-'06. My wife uses these to hunt deer with up in northern Michigan and at ~2,500fps, they are very effective and do not over-expand. I would think they would still continue to perform down to perhaps as slow as 1,800fps impact velocity. Is that the bullet you have tested?

 

[jblomenberg16]

To stay within the OAL limitations, and not impinge too greatly on powder space, are you best off with a round nose bullet or is it optimized for sharply pointed bullets?

I handload 125 Nosler Ballistic Tips with "Youth" loads of H4895 out of a 30-'06. My wife uses these to hunt deer with up in northern Michigan and at ~2,500fps, they are very effective and do not over-expand. I would think they would still continue to perform down to perhaps as slow as 1,800fps impact velocity. Is that the bullet you have tested?

My early load development work on the 125's has me pushing them to about 2250FPS. I need to do some more work with that, but that makes the 125 a GREAT bullet out of the 300BLK.

Velocity at 200 yds is still above 1800FPS (minimum expansion velocity) and at 300yds is 1660FPS.

Energy is on part with a 123FMJ from the 7.62x39, and with the better BC out performs it on energy from 50yds onward.

.300BLK 125gr Nosler BT

Range (yds) Energy (FPE) Velocity (FPS)
0 1405 2250
50 1276 2144
100 1156 2041
150 1044 1940
200 942 1842
250 849 1749
300 764 1660

 

[Slow Hand]

I'm hoping to do similar tests this weekend. Mine will be a bit off because I've got a 20" sks, 18" .223 AR, and a 16" .300 AR. The two ar's have scopes on them but I'll dial them down to 1.5x and the sks will have tech sights. I'll be chrono'ing 125 Speer TNT's and my cast 225 round nosed bullets.

Doug K

 

[jblomenberg16]

I'm hoping to do similar tests this weekend. Mine will be a bit off because I've got a 20" sks, 18" .223 AR, and a 16" .300 AR. The two ar's have scopes on them but I'll dial them down to 1.5x and the sks will have tech sights. I'll be chrono'ing 125 Speer TNT's and my cast 225 round nosed bullets.

Doug K

Looking forward to your results as well!

 

[jblomenberg16]

I had a chance to try another load today, this time the Hornday 110gr V-Max. I have really liked the 60gr V-max in .223, so was eager to try out the .308 caliber offering.


The results were pleasing, and I was able to get pretty close to the book load velocity at max load. I did push out the OAL just a bit longer than book however.

The conclusion at this point is that the 125gr Nosler Ballistic bullet still has a bit of an edge in energy over the 110gr V-max. I'm not sure the minimum expansion speed for the 110gr at this time, but it stays just over 1600FPS at 300yds.

To get similar energy to the 125gr Nosler, one would need about 2400FPS at the muzzle out of the 110. That would require going over the max listed load in the Hogdgon manual however.


For fun I did add in a column for the 60 gr V-max. I have a "Hot" load for it at 2966 FPS from my 16" barrel. While considerably faster than the larger .308 rounds, it still weighs in at 1/2 of the total weight, so can't make up for it in the energy down range.

 

[LEaSH]

Great info.

Do you extend the OAL to reduce the chances for over-pressure? Other reason?

 

[jblomenberg16]

Great info.

Do you extend the OAL to reduce the chances for over-pressure? Other reason?

That was part of it. I started out close to the max load, so wanted to give myself a little margin. The other reason was that I wanted to push the bullet out a bit farther to be consistent with where I had the 125gr bullet loaded at.