Looking for data/experience with 300 AAC Blackout and Speer 125gr TNT.

So I am working up a duel purpose round. Primarily a cheap plinking round but one that uses a bullet that is not FMJ so it still legal to hunt with in TN. Hence the reason I selected the Speer 125gr TNT. They were also on sale at Midway.

So do you guys have any experience loading this bullet in 300 BO? I have a fair bit of H110 I would like to use but if you guys have data for other powders I would love to see it to. As much data as your willing to share.

OAL, charge weight and velocity is most helpful.

Thanks

adcoch1 said:

H110 and the 125 grn tnt is my go to general purpose 300 blk super load. I will pull my notes and send you charge weights, but it is near the top of the load charts from Hornady. Not totally topped out though. Very accurate in my cmmg barreled upper, and I can hunt with it too.

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That would be great. I am looking for sanity checks and having other real world data helps. I am still going to work up the load starting low but having data to compare it to gives me more confidence.

My hunting super sonic round is Barnes 110 gr TAC-TX pushed by H110 but those are spendy for ringing steel and blasting armadillos.

I also have a good plinking and hunting subsonic loads. The only thing I am missing is a cheap plinking load for supersonic.

I have some lil'gun I could try if you want to share your data. I tried it with subsonic loads and didn't like it. It mostly gets used for light 450 Bushmaster loads. Lil'gun under a 200gr Barnes TSX is impressive.

So after a nice suggestion from adcoch1 and some measuring myself here is my initial test ladder loads.

300 AAC Blackout
Case: mixed, once fired, Remington and Barnes
Bullet: Speer 125gr TNT
OAL: 2.060 inch with a light crimp
Primer: Winchester Small Rifle
Powder: Hodgdon H110
Ladder Charges: 17.5gr, 17.9gr, 18.2gr & 18.5gr

I decided on the OAL as this length put as much cylindrical part of the bullet in contact with the neck as possible without over inserting the bullet. Any deeper and it would have been below the bottom of the neck.

As for charge weight I looked at a lot of data (thanks guys for all the links) but I relied heavily on Hodgdon's published data for a 125gr Nos BT with a Max of 18.5gr and given the length and shape of that bullet I suspect it is taking up more case volume than my OAL and the TNT bullet. Hodgdon lists 18.5gr under the Nos BT as a compressed loads. 18.5gr under the TNT with the 2.060 OAL is NOT a compressed load, its close but not compressed so I suspect my pressure will be similar or less.

I loaded enough of all four charges so I should be able to chrono 5rds of each from both a 9-inch gun and a 16-inch gun. Hopefully that happens next weekend.

Thanks again for all the help. I will be sure to post chrono data and accuracy data too if I get it.

ETA: Got to have a pictures:



Left to right: 220gr Maker REX (sub), 220gr Berry (sub), 125gr Speer TNT, 110gr Barnes TAC-TX.


TNT left, Barry's Right.

Walkalong said:

Smart.

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I have my moments, just wish they where more frequent.

Some data and some failures...

I got velocity data but failed to get an accuracy evaluation since the scope was loose on the 16-inch gun and we did not notice it until after shooting.

300 AAC Blackout
Case: mixed, once fired, Remington and Barnes
Bullet: Speer 125gr TNT
OAL: 2.060 inch with a light crimp
Primer: Winchester Small Rifle
Powder: Hodgdon H110

Charge: 17.5gr
16-in Average: 2105 fps
9-in Average: 1929 fps (2rds Chrono Battery died)

Charge: 17.9gr
16-in Average: 2121 fps
9-in Average: 1955 fps

Charge: 18.2gr
16-in Average: 2143 fps
9-in Average: 1968 fps

Charge: 18.5gr
16-in Average: 2207 fps (4rds missed one gate)
9-in Average: 1987 fps

The 16-inch gun was my brother's and had a loose scope that we did not notice until after shooting. So the groups were OK but we can't make a real evaluation from them due to the loose scope. The 9-inch gun was my pistol and it did not particularly like the loads. It was shooting 2-3 inch groups at 50 yards. I am going to load some more of the 18.5 gr load and we are going to shoot for accuracy in both of our 16-inch guns. I did have one round setback into a case causing a malfunction. I think with the next batch I will increase the crimp a modest amount. I am not too disappointed in the accuracy in my pistol since it has become pretty much a dedicated sub-sonic gun.

My try a small batch with 4227 and Lil'gun too and see if that shoots more accurately. Got lots of bullet so I can afford to do some more experimenting.

beeenbag said:

Well... whatever happened here? Lol

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Well I loaded another small batch of the 18.5 gr load and that with a properly tight scope proved fairly accurate and functioned well in my brother's gun. So I cranked out a batch of about 400 rd of it for him and away we have gone. He has not used it all up yet so I have not reloaded any more recently. I have personally not used the load much as currently if I am using 300 Blackout its suppressed and subsonic.

beeenbag said:

Did you have any more set back issues after a tighter crimp? And any tries with the lil gun? I’m
Curious to see if your results yield the same as mine with lil gun and a 10” barrel. I’m getting almost 2200 fps with a 125g bullet from a 10.5”

View attachment 939225

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My setback issues seems to have been resolved. It was less of adding crimp and more of making sure all my cases were the same length so I did not get too much crimp on a few and not enough on a few others. Just being careful and thus more consistent seemed to have resolved that issue.

I have not tried Lil'gun yet but I will. I have a pound I used some of with some lighter 450 Bushmaster bullets and will give it a try the next time I convert the press back to 300 BO. Thanks for sharing the data that will be a good reference point when I chrono my version.