.300 BLK vs. ballistic gellatin

[82nd airborne]

I did a test last night with the .300 BLK, 16.5", Remington factory subsonic ammo loaded with 220g SMK.
I know, I know! Its not done with boolits! But, I only had a couple blocks of ballistics gell. I had to shoot each one with the same load and all other factors equall to make it a decent test. All of them look like the ones below.
I hope to get time to post pics and results of various cast boolits in the ballistics gell in the next week or so, out of the Blackout.

There are a couple more pics of Blackouts uppers on our website now, too buy the way. Over the next couple weeks it will be getting constantly upgraded, with shopping cart, many more upper, lower, complete ar-15, and bolt gun options.

Below is the pic of the ballistics gellatin, after being shot through the center with the 220gr match king. I cut it down the center of the "wound channel" so to speak. You can tell that the bullet yawed a little, but didnt come close to tumbling.

And this is why we use cast boolits, because you can make them expand even at 975fps! I hope to prove this in the next week.

[rjrivero]

Thanks, Aaron for doing this. I look forward to the boolit comparison!

[82nd airborne]

You are quite welcome! I too am looking forward to it, but then again, Im getting to shoot something and act like Im working, so why wouldnt I!?
The Germans did extensive testing and decided that 7mm was the optimal bullet size for a battle carbine. I am anxious to see how the blk stacks up against the 7x45.

[Dannix]

Almost thou persuadest me to go for the .300Blk. :mrgreen:

I'm interested in your boolit gel tests results. You going to use a 2-parter, HP, or nose annealed boolit, or just plain 'ol FN?

[82nd airborne]

Well sir, Im going to do my best to try em all! I dont have any HP moulds though, so that one may be out, unless someone wants to donat a few to the cause.

[wiljen]

Get one of JiminPHx hollowpointing Jigs and you can make anything into an HP - Highly recommend them and the cost is minimal.

[dk17hmr]

Maybe you can explain the subsonic thing to me, I understand getting rid of something quietly has its benefits...shooting deer on golf courses comes to mind. But for normal hunting why go subsonic? 125gr Nosler Ballistics will hit 2100 easy out of my 300 whisper and are very effective on antelope and deer sized game.

That being said I have a bunch of Ranch Dogs 311-170's cast (havent gotten these to feed in my AR just yet) and some Lyman 195gr spire points as well if you want them.

[82nd airborne]

If you dont have a suppressor, I see no point in shooting subsonic. However If you do have a suppressor, and a NOE 247gr whisper boolit mould (coming up!) and can make minimal noise while putting out some worth while energy, the stars align themselves, and the moon moves close to facilitate a romanic gravitational pull that makes the ladies swoon. And shooting stuff with almost no noise or recoil is amazing.

[dk17hmr]

Thats what I thought. What powders are you getting to function with 200gr booilts at subsonic velocities? Im going to play with mine some more this summer, or at least when the snow melts so I can find my brass :)

[wiljen]

I've been having good luck with Trailboss in the 6.8 for subsonics

[82nd airborne]

Trailboss is amazing.

[looseprojectile]

I'm new here. What do the letters BLK stand for?

Life is good

[82nd airborne]

.300 AAC Blackout. Sorry, that one is a little to new to be abreviating!

[Dannix]

I've been having good luck with Trailboss in the 6.8 for subsonics
What boolit/jword are you using?

[wiljen]

What boolit/jword are you using?

Been using the 135gr SMK and the RCBS 150gr Cast 270-150-SP.


The cast shoots almost as well as the SMK at 1050fps through a Gemtech can and is dead quiet. None of the TB loads I have been using even think about cycling the action. RL-7 has come closest to cycling and staying subsonic but it seems to be pretty flaky at that load level and I gave up on it for that reason. (Was seeing swings of 200 fps shot to shot).

[JRMTactical]

Hey Aaron, per my PM I am gonna get one of those 10.3" (maybe shorter) barrels, since I'm already getting a 762-SD for my bolt gun. Keep up the good work and let us know about the further tests!

[82nd airborne]

Sweet, thatll be dealer price, it will. Shoot me an email and Ill get you set up.

[Idaho Sharpshooter]

Aaron,

you are killing me man!

I was all set to have you build me a 358 Delta upper, and mess with different brass, mags, etc.

Swede is making a 247gr GC 30 caliber mould now?

thanks, I think!

Rich
Sua Sponte

[Artful]

Aaron,

you are killing me man!

I was all set to have you build me a 358 Delta upper, and mess with different brass, mags, etc.

Swede is making a 247gr GC 30 caliber mould now?

thanks, I think!

Rich
Sua Sponte

http://castboolits.gunloads.com/showthread.php?t=102895
http://i69.photobucket.com/albums/i80/swedenelson/1111-134-311247GrFNWhisper.jpg
and plain base
http://i69.photobucket.com/albums/i80/swedenelson/1111-134-311247GrFNPBWhisper.jpg
loaded up
http://i69.photobucket.com/albums/i80/swedenelson/1111-134-311247GrFNWhisperCart.jpg

[Artful]

I did a test last night with the .300 BLK, 16.5", Remington factory subsonic ammo loaded with 220g SMK.

I know, I know! Its not done with boolits! But, I only had a couple blocks of ballistics gell. I had to shoot each one with the same load and all other factors equall to make it a decent test. All of them look like the ones below.

Below is the pic of the ballistics gellatin, after being shot through the center with the 220gr match king. I cut it down the center of the "wound channel" so to speak. You can tell that the bullet yawed a little, but didnt come close to tumbling.


So is this with 1:8 twist and did you Chrono the factory ammo (spec's at 1010)
and what distance to the blocks?

[Idaho Sharpshooter]

Artful,

my thanks to you sir! Would you recommend a twist for this bullet?

thanks again,

Rich
G/75th

[82nd airborne]

So is this with 1:8 twist and did you Chrono the factory ammo (spec's at 1010)
and what distance to the blocks?

It clocked 960fps out of a 9" and 1015 ave out of a 16". Blocks were 10ft. 1:8".

[82nd airborne]

Your welcome there Idaho! ha! I have really been enjoying the blk lately, but that doesnt count for anything, because if it slightly resembles a gun, Im all over it!
I would still use 1:8 for Swedes boolit, mainly so I can still run the light boolits at faster velocities with decent accuracy.

[Artful]

for long heavy 30 cal 1:8 is best if going subsonic & supersonic - some have had 1:7 which overstabalizes at supersonic - I'm actually suprised the 220's didn't yaw more - do you have a 240 SMK to try?

[82nd airborne]

I dont, but I would like to. I will be getting some in the near future to test. Those things are rediculously expensive though.

[Dannix]

And this is why we use cast boolits, because you can make them expand even at 975fps! I hope to prove this in the next week.
This still on your to-do list?

[82nd airborne]

Yeah, I have been slowed down from the flu and my back going out for the past couple weeks, but I am still planning on getting it done here shortly!

[Dannix]

No problem, just curious.

[45r]

I read an article today that says you can load em backwards and they will work.Something about they stabilize better.Sounds like they been doing them backwards since WW 2.There is a lot more to subsonic loads than I thought according to the article.

[Dannix]

I read an article today that says you can load em backwards and they will work.Something about they stabilize better.Sounds like they been doing them backwards since WW 2.There is a lot more to subsonic loads than I thought according to the article.
There was a discussion here a while back. In a nutshell the base is what is more important for subsonic and the nose less so. So I wasn't surprised to see a backwards boattail used for subsonic, but now there could be an issue with uniform release from the muzzle crown.

As I understand it, the ideal subsonic would have a nice bit meplat for terminal damage (because again, less penalty than with supersonic), and a monstrous rebated boattail to ensure uniform release.A boolit like this would of course require a larger case capacity than we have with the .300Blk though, since the crimping location is move forward with such a boolit design. This is on my someday-try list as it would allow for a big and heavy boolit without having to give up case capacity for supersonic loads.

...I tried to find the discussion I was thinking of, but coundn't find it. This thread touches on boolit base though: Reload this Page Rounded base ...like bevel base?? Am I too picky (http://castboolits.gunloads.com/showthread.php?t=88869)


Edit: Here we are. Holey Gas Checks -- brilliance or noobish stupidity (http://castboolits.gunloads.com/showthread.php?t=85491)
Subsonic (below about 1090 fps depending on air density) bullets have their BC more affected by the shape of the base than the nose. A very blunt bullet can have its BC improved by nearly 40% by changing from a flat base to a rebated boattail shape, whereas a supersonic bullet will only improve by 10-15% by changing the base, because the shock wave generated at the nose is so much greater an effect than base drag. Without the shock wave, most of the drag is at the base. Therefore, subsonic airgun, shotgun, and blackpowder bullets do not really need a longer ogive to get higher BC in comparison to using a boattail shaped base. The problem is that a boattail base is incompatible with a hollow base for sealing the bore. Therefore, a special under-cut form of rebated boattail may be used to create a seal at the boattail shoulder.
http://www.corbins.com/minwt.htm

I do intend on giving this a go, wilk case checks et al, one of these days...

[82nd airborne]

As soon as I can, I will do some testing with this. Very interesting.

[rjrivero]

Yeah, I have been slowed down from the flu and my back going out for the past couple weeks, but I am still planning on getting it done here shortly!

Do we need to send you a Gift Certificate to the Chiropractor to get these gel tests done? ;)

I kid Aaron. Get better soon. I look forward to your results.

[RU shooter]

Not trying to hijack but how does this ctg. do supersonic with lets say 150-180 gr. cast with that fast twist is 1600-1700 fps do able with accuracy ? I 'd really like a 30 cal AR15 but dont want to be limited to subsonic shooting with cast or shoot only at speeds that limit me to 100 yds. BTW what kind of accuracy are you guys getting at 100/200 yds with this round shooting cast.

Thanks,Tim

[Artful]

Not trying to hijack but how does this ctg. do supersonic with lets say 150-180 gr. cast with that fast twist is 1600-1700 fps do able with accuracy ? I 'd really like a 30 cal AR15 but dont want to be limited to subsonic shooting with cast or shoot only at speeds that limit me to 100 yds. BTW what kind of accuracy are you guys getting at 100/200 yds with this round shooting cast.

Thanks,Tim
Tim, it's basically a 30-30 or 7.62x39 performance envelope
check bottom of page for reloading links
http://castboolits.gunloads.com/showthread.php?t=102160&page=7

accuracy of course has many variables but people with better grip on shooting then myself are getting groups as small as 1" at 200 yards and have printed groups to prove.

[Dannix]

Gel tests for lighter, supersonic loads on AAC's site, FYI:
http://300aacblackout.com/resources/300AACBlackout06OCT2010.pdf

[Artful]

Aaron you alright?

[82nd airborne]

Ha! Sort of! I had to put my testing on hold for a bit. I am getting several surgeries in San antonio, so It looks like I will be living there for most of the summer. My grandfather lives down here though, And he is married to the sweetest lady, I bet I can get her to cook me up some gellatin.
I havent forgotten about you, I actually have those six 240's taped to the front of my reloading desk.

I am spending most of the available time in the shop, but It looks like I will take a couple weeks off after this next surgery, and be in a wheel chair, so I can imagine I will be testing untill my face turns blue.

[bruce drake]

Aaron,

I hope you are getting the care that you deserve! Keep up the positive posts. You'll be amazed how well you heal when you are upbeat. But then again, I know you've got the big guy up above on your side in all this as well.

Now, while you are in that wheelchair you should design some gunmounts for the arms. maybe a pintle arrangement might work ;)

Bruce

[DIRT Farmer]

Aaron, just put you on the prayer list, you have to be in shape when I get down ther to fish and shoot, If I can figure out when.

[82nd airborne]

Thankyou!

Bruce, just bring me back a couple mod93's for my wheelchair!

[bruce drake]

not about to run afoul of the law ;) but we'll see what drops into the CONEX in the fall.

Bruce

[Idaho Sharpshooter]

God Bless you, and get better soon.

Rich

I am waiting for my stuff from LAR to send to you for barreling.

[rsilvers]

Someone needs to take some lead bullets and load/sell $9 a box subsonic 300 AAC BLACKOUT ammo.

Here is some load data:

http://www.silencertalk.com/forum/viewtopic.php?f=128&t=73990

[Artful]

Biggest problem is uncleanable suppressors people buy and might use.
Be ok if used a cleanable can like maybe 9mm but if they use a 30 cal Aluminum they would be messed up.
Probably use plated bullets without issue, but only a few 30 cal plated are made and none in the heavier ranges 200-240 that are required.

[DrB]

I played with this some in 22 caliber... And yes, there is a lot of reversed spitzer history back to at least ww 1.

What I found was that the base of the bullet being in the bore when the barrel uncorks seems to make the bullet more prone to initial upset due to escaping gas. I was using an ss109 steel nosed projectile so static stability was somewhat enhanced as compared to nose forward.

A rebated boat tail may help some, but I doubt it is worth fooling with other than as a matter of academic curiosity.

I have had the idea of trying the reversed spitzer over again with an integrally silenced rifle and barrel ported with rifling unrelieved. This might require some edm work, or careful machining + deburring. The idea would be to relieve gas pressure before mechanically releasing the bullet.

At the end of the day, though, this would be of questionable utility... A moderately aerodynamic subsonic bullet flies a very arced trajectory with increasing range, and the benefit of increasing ballistic coefficient is very marginal. If you pick a decent larger caliber to start with and play with a ballistic computer, you'll see that improvement to bc won't save you much in drop vs. range as compared to total drop... The way to get significant reduction in downrange drop is to increase velocity, and this will significantly increase flight noise of the round.

Best regards,
DrB

Edit: so ideally subsonically you want a rounded nose long trailing edge symmetric airfoil-like shape. A "teardrop." Reversing a boat tailed spitzer gives you the closest thing to this you can get off the shelf, but, my experience was I got accuracy problems. Looking at ballistics tables of drop, it doesn't seem to make much sense as compared to going to a larger caliber and/or higher sectional density bullet.




There was a discussion here a while back. In a nutshell the base is what is more important for subsonic and the nose less so. So I wasn't surprised to see a backwards boattail used for subsonic, but now there could be an issue with uniform release from the muzzle crown.

As I understand it, the ideal subsonic would have a nice bit meplat for terminal damage (because again, less penalty than with supersonic), and a monstrous rebated boattail to ensure uniform release.A boolit like this would of course require a larger case capacity than we have with the .300Blk though, since the crimping location is move forward with such a boolit design. This is on my someday-try list as it would allow for a big and heavy boolit without having to give up case capacity for supersonic loads.

...I tried to find the discussion I was thinking of, but coundn't find it. This thread touches on boolit base though: Reload this Page Rounded base ...like bevel base?? Am I too picky (http://castboolits.gunloads.com/showthread.php?t=88869)


Edit: Here we are. Holey Gas Checks -- brilliance or noobish stupidity (http://castboolits.gunloads.com/showthread.php?t=85491)
Subsonic (below about 1090 fps depending on air density) bullets have their BC more affected by the shape of the base than the nose. A very blunt bullet can have its BC improved by nearly 40% by changing from a flat base to a rebated boattail shape, whereas a supersonic bullet will only improve by 10-15% by changing the base, because the shock wave generated at the nose is so much greater an effect than base drag. Without the shock wave, most of the drag is at the base. Therefore, subsonic airgun, shotgun, and blackpowder bullets do not really need a longer ogive to get higher BC in comparison to using a boattail shaped base. The problem is that a boattail base is incompatible with a hollow base for sealing the bore. Therefore, a special under-cut form of rebated boattail may be used to create a seal at the boattail shoulder.
http://www.corbins.com/minwt.htm

I do intend on giving this a go, wilk case checks et al, one of these days...