300 AAC Blackout fad over?

[mickb]

Penetration for solid projectiles is not necessarily linear relationship to velocity, and does not hold across multiple medias. its probably better keeping armour piercing out of normal rifle debates especially, the mechanics behind it are beyond highschool maths. Penetration comes down to the qualities of the target, hardness relative to target, all the metallurgical factors relating to strength, stabilisation in the media etc. Projectiles may use mechanisms of cavitation, breaking, shattering, or causing stretch failure (like a 12 ga punching a plug out of light steel). Shooting soft metal a certain energy may get a certain penetration, but with hard metals you may have more of a pass/fail relationship, if it can't make it right through, it rebounds, in your direction!

There are also velocity nodes where more velocity causes less penetration. An engineer over at accurate reloading called Harald did a lot of tests of elephant gun solids at different velocities and sometimes found penetration dropped at some velocity point, then increased again at another. The theory was many of the traditional round nose FMJ in the elephant guns werent blunt enough. Blunt bullets are theorised to set up a cavitation bubble where they can continue to rotate gyroscopically. This stability is not actually possible iby itself in fluids being 1000x denser than air. ( Its why elephant gun FMJ and solids are blunt, not spitzers as spitzers are too prone to veering of course or tumbing after long wound paths in fluid animal bodies) . The theory was he was picking up rotational instabilities when the bullets were pushed at a certain velocity - relative to their shape..

Anyway its too complicated to describe every instance with a basic momentum or kinetic energy formula.

[bladeracer]

...or causing stretch failure (like a 12 ga punching a plug out of light steel).

An 8x57mm cast lead 180gn bullet at 2500fps punched a steel "plug" out of 8mm plate, I still have it somewhere.

[in2anity]

Considering the forecast for Winchester powders in the Australian is looking bleak, I went back to revisit adi's AR2205 under the budget Speer 125gr TNT bullet. Sadly we cannot bank on Hogdons lilgun supplies in the foreseeable future

In the interim I've been learning more about differences between extruded "stick" powder vs double-base ball type powder. Lilgun is a type of ball powder. What does this mean? Well compared with extruded powders, ball powders are generally harder to ignite, and often give poorer standard deviations. Therefore lilgun really demands a magnum primer. And the harder magnum primers do not gel with with the (at least early model) RARRs (like mine). So in many ways, in my RARR 300aac it's actually more suited to an extruded powder like AR2205 (with a regular SR primer such as the cci400).

AR2205 was definitely a little finickier to get to group (at least compared with the lilgun loads), but thankfully I found a node with this powder+projectile+rifle combo last night:

18gr AR2205 under Speer 125gr "TNT", light crimp. 4x scope.

speer.jpg (1013.76 KiB) Viewed 6841 times

For the record I went up to a compressed 19gn AR2205 load without any pressure signs (AR disclaimer in a bolt gun I might add!!). The 18gr load is yet to be chronoed, but from my previous findings, std-dev should be more than adequate with AR2205. I take comfort in knowing it's not the very hottest of loads as I was seeing primer pockets opening up with hot lilgun loads.

This journey has also brought into light the potential need for a crimp; not from an accuracy perspective, but rather the RARR seems to be fairly rough on the projectile as it feeds from the rotary magazine. I feel sometimes the gun would set-back the pill, leading to flyers and pressure spikes. I'll be crimping from now on just to relieve my anxiety about any set-back, which really makes a bullet with a cannelure (like the Hornady SST) a little more desirable... still a light crimp on the cannelureless Speer bullet certainly does not seem to do any measurable harm to group sizes.

[gunnnie]

Handy to know. Looks like it'll be worth while re-visiting loads for my RARR also.

[JimTom]

Mate I have been running the Hornady 125 SST WITH AR2205, no crimp and have had no issues at all.
I have just started experimenting with the Speer 130 HP. Whilst they shoot quite nicely, I have an issue with the last round feeding properly from the magazine. I initially seated the projectiles a few though of the lands however could not get them to feed at all. I am now loading them at spec length and they feed nicely with the exception of the last round out of the magazine. Any suggestions?

[JimTom]

Just to clarify mate I have the Ruger American Ranch with rotary mag.

[in2anity]

Mate I have been running the Hornady 125 SST WITH AR2205, no crimp and have had no issues at all.
I have just started experimenting with the Speer 130 HP. Whilst they shoot quite nicely, I have an issue with the last round feeding properly from the magazine. I initially seated the projectiles a few though of the lands however could not get them to feed at all. I am now loading them at spec length and they feed nicely with the exception of the last round out of the magazine. Any suggestions?

Don't really have any suggestions unfortunately JT - my rotary mag also has same problems with the speer bullet - some have suggested filing the feed lips a touch to get the round to feed a tad higher. Other than that - I picked up the Lucky13 10-shot mag. It feeds reliably, but only if you cycle the action with authority - if you limp-wrist it, the rounds jam. But the problem with that is it puts more wear on your brass... plus the L13 mag is a bit of a monstrosity on the little rifle.

[JimTom]

Yep I can imaging it would be mate. I like the rotary mag being flush with the bottom of the rifle, bit easier on the back when rifle is slung whilst riding motor bike.

[gunnnie]

I have a box of those Sierra 130gn Hog Hammers but haven't got round to trying them in my RARR yet. Have been using Sierra 125gn and 110gn pills.

[JimTom]

Me too mate, if you happen to try them before I do then post the results for us to have a look at.

[in2anity]

Picked up a box of the Hornady SSTs - feeding 100% reliably out of the factory rotary. It’s a bit of a shame, as those TNT bulk packs are very well priced. You get what you pay for I suppose

125gr TNT vs SST

C32A29D4-4B79-4329-B11C-F898851D6291.jpeg (1.66 MiB) Viewed 6783 times

[JimTom]

Yep the 125 SST feed faultlessly out of mine too mate. Fortunately they are accurate and perform well on the hogs too. Seems the magazines just don’t like feeding hollow points.

[SCJ429]

Picked up a box of the Hornady SSTs - feeding 100% reliably out of the factory rotary. It’s a bit of a shame, as those TNT bulk packs are very well priced. You get what you pay for I suppose ]

My experience with the Speer TNT is that they are very effective, at least as good as the SST. The TNT has accuracy potential way beyond its price point. I am betting the TNT works well for you too.

[gunnnie]

Yep the 125 SST feed faultlessly out of mine too mate. Fortunately they are accurate and perform well on the hogs too. Seems the magazines just don’t like feeding hollow points.

Seems odd as when you look at the two projectiles, they look almost identical in dimensions, location of ogive etc. You'd think that both would feed without issue.

[JimTom]

Yep the 125 SST feed faultlessly out of mine too mate. Fortunately they are accurate and perform well on the hogs too. Seems the magazines just don’t like feeding hollow points.

Seems odd as when you look at the two projectiles, they look almost identical in dimensions, location of ogive etc. You'd think that both would feed without issue.

Yes mate I agree. It is perplexing. The last round out of the magazine seems to drive straight up and jam.

[in2anity]

For those of you sporting the RARR - when slung-up, I noticed the factory bolt handle was uncomfortably small, to the point it was leaving the palm of my hand tender after a long session. So I swapped it for a Glades Armory version:

this:

factory bolt handle for tiny hands

IMG_9172.jpg (551.8 KiB) Viewed 6546 times

became:

no more sore hand after a long slung-up session

IMG_9177.jpg (544.32 KiB) Viewed 6546 times

No dramas coming through AUS customs. Much easier to cycle the bolt now

Oh BTW I shot an arbitrary test load of 18gr AR2205 under the 125gr SST at 100m - group was pretty horrid. Back to ladder tests for me now...

[bladeracer]

For those of you sporting the RARR - when slung-up, I noticed the factory bolt handle was uncomfortably small, to the point it was leaving the palm of my hand tender after a long session. So I swapped it for a Glades Armory version:

this:

IMG_9172.jpg

became:

IMG_9177.jpg

No dramas coming through AUS customs. Much easier to cycle the bolt now

Oh BTW I shot an arbitrary test load of 18gr AR2205 under the 125gr SST at 100m - group was pretty horrid. Back to ladder tests for me now...

I just use the Hornady rubber balls that press onto the bolt knob.

[JimTom]

I am surprised that the 125SST didn’t perform for you mate. I am loading 17.5 AR2205 from memory and they go really well. Let us know what you come up with.

[in2anity]

I just use the Hornady rubber balls that press onto the bolt knob.

Ha, did not know about those Blade - probably shoulda asked you blokes before spending that money certainly would have solved my problem with a lot less fuss

[in2anity]

I am surprised that the 125SST didn’t perform for you mate. I am loading 17.5 AR2205 from memory and they go really well. Let us know what you come up with.

Conditions weren't great - dead-perpendicular gusts anywhere from 1 to 20km/h - so that was surely contributing to some poor shooting. My refined lilgun+Speer loads did shoot better however - it’s funny, my sling groups were basically as good as my bench-rest groups that day - go figure

A bit of ladder testing should do the trick I reckon - the nodes seem to be there, just gotta find em!

[in2anity]

My experience with the Speer TNT is that they are very effective, at least as good as the SST. The TNT has accuracy potential way beyond its price point. I am betting the TNT works well for you too.

Now that I found my node, the Speers indeed do group pretty consistently. They just don’t feed well in that Ruger. In contrast they feed faultlessly in the Tikka 308 - but I prefer the little blackout for a stack of other reasons.

I also picked up a box of Noslers to try - they are notably more expensive than the Speers and Hornadys.

[JimTom]

Have you varied the length mate to see if it helps feeding? I had mine originally just off the lands and they wouldn’t feed period. I then loaded them at advertised length in ADI loading data and they go well with the exception being the very last round sometimes plays up.

[in2anity]

Have you varied the length mate to see if it helps feeding? I had mine originally just off the lands and they wouldn’t feed period. I then loaded them at advertised length in ADI loading data and they go well with the exception being the very last round sometimes plays up.

Loading to spec JT. I think it may be related to the hollow point - both the nosler and hornady with their ballistic tips seem to feed fine.

[in2anity]

mixed bag of 125gr pills at 50m over AR2205

mixed.jpg (1.18 MiB) Viewed 6830 times

JimTom you were on the money with your suggested 17.5gr load under the Hornady SST!

And SCJ429, I think you are onto something with your observations that the Speer Bullet shoots way above its price-point. Given my overall experiences with the 300aac, I think the Speer bullet does group fractionally better than the Hornady. Nevertheless, the Hornady bullet feeds very reliably, so I guess I'll stick to the Hornadys when reliability really matters (like during a comp or when hunting).

I've only shot that one (arbitrary) Nosler load. I'm sure it would also have some sweet spots, but compared to the others it's just so darned expensive, so I'll doubt I'll pursue that line of enquiry. I'll back-burner that one for a rainy day.

At this point, I'm going to say the little RARR-300aac is a true one-minute gun. The cartridge is certainly a lot finickier than say a 223, but using the collet die, it's a superb handloader's cartridge. Neck tension with this cartridge seems particularly pertinent. The 300aac is economical, low recoiling, has excellent case life and runs cool.

[JimTom]

Yep like you mate I love it. Great bit of kit.

[SCJ429]

Nice work, heaps of options there. You have a good load for all three projectiles right there.

[jovialjosie2002]

i still plan on buying a CZ 527 carbine in 7.62X39, to me the 300 offers an alternative but the only advantage it has is 308 bullets

Firstly....your cz527 in 7.62x39 WILL SHOOT .308 PROJECTILES JUST FINE.....mine does.....
Secondly.....buy anything but a cz527 in 7.62x39...it just wont feed properly....get a Howa or Ruger in 7.62x39....and shoot Hornady steel case sst....they're only 90 cents a round....it aint worth reloading...

[SCJ429]

If you want good results Josie, it is always worth reloading.

[Blr243]

No, the blackout fad is not over , mine has just been cased and bore sighted and it’s headed for the bush tonight

[JimTom]

Enjoy it mate. Great little round.