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[tagonzo]

Hi all,

Here are the results from another day at the range. Some loads with 300MP.
Sorry for the long post. I wanted to explain a bit about each load, rather than just post a bunch of load data.

I have a CMMG 16" barrel in a AR-15.
Temperature for the day was about 60 deg.
Most everything here was 5 shot groups, averaged chrono data.

Bullet............wt......Powder...wt......fps......OAL

Hornady V-Max....110gr....H-110....19.5....2298....2.040
Hornady V-Max....110gr....H-110....20.0....2346....2.040
Hornady V-Max....110gr....H-110....20.5....2376....2.040

Sierra MK........125gr....H-110....18.5....2203....2.225

PPU M80 FMJBT....145gr....H-110....16.0....1928....2.080

Hornady FMJBT....150gr....H-110....17.0....2019....2.065
Hornady FMJBT....150gr....300MP....17.0....2017....2.065
Hornady FMJBT....150gr....300MP....17.5....2025....2.065
Hornady FMJBT....150gr....300MP....18.0....2102....2.065 Hot *

* I do not recommend 18gr of 300MP with 150gr. See below.


The 110gr V-Max series was just a test to observe over pressure signs. Hodgdon lists this bullet with a H110/20gr as max. So, I did a 1/2 below and above that to see what the cases look like. All the loads showed some primer flattening, and none were completely flat. The rest of the differences were not great, only minor.
19.5 - no primer flow, no ejector marks.
20.0 - hint of primer flow, hint of ejector mark, on a couple of cases.
20.5 - mild primer flow, hint of ejector mark, on all cases.
Primer flow being the primer pushing up around the firing pin pocket.

So using this as a benchmark, it seems that the start of primer flow and ejector marks means it is getting close to or is at the max that I would want to go when working other loads. It's possible that different bolts and different guns may start to make ejector marks at a different level of pressure. These are my observations for my gun. I also noticed that the brass was much more dirty with brunt powder on the H110/20.5gr load, from the extra pressure pushing the gases back along the case.


Most accurate of the day was the Sierra MK 125gr with H110/18.5gr. This made a 4 shot group of about 1 inch at 100 yds. Some primer flattening, slight primer flow on all cases, hint of ejector mark on a couple of cases. I believe this may be near or at the max, but I think I'll keep this load. Has anyone else tried this load? If you have, what's you feeling on the pressure signs? I like the velocity and accuracy, and would like to keep it.

The M80 load is going to be my plinker load for now. No signs of pressure. It could use a bit more powder and go a bit faster, but this load seems to work plenty good enough for plinking. At least until I find out how to make it go 2000 fps safely, and accurately.

The 150gr series was to test 300MP some more. The H110/17gr load was starting to show signs of pressure. Primers showed some flattening, mild primer flow, a bit more than a hint of ejector marks. So if I had to guess, I would say this is at max load or just a bit more than max. So, I would go no more than 17gr, and maybe a couple of tenths less. Maybe adjusting the OAL a bit longer could help this load.

The 300MP/17gr load seemed similar to the H110/17gr load. The primers were similar to the H110/17gr load, maybe just a bit less pressure, and just a hint of ejector marks on only a couple of cases. I think this load was the most inaccurate of the day at about 4 inches at 100 yds. I think I would call this one a safe max.

The 300MP/17.5gr load seemed to have all the same pressure signs as the H110/17gr load. A little more accurate, but still not good. Probably at max, or a touch more.

The 300MP/18gr load was hot. Gun recoil was noticeably more. A bit more primer flattening than the others, but not fully flattened. The primer flow was clearly there, but not bad. The ejector marks were clearly visible on all cases. I don't think I'm going to load this again.


Ok, so here is my general feeling about Alliant 300MP. It looks almost identical to H110. It measures almost identical as H110. I did not adjust my powder bar on my Dillon 550B when I switch from H110 to 300MP, and the weight was the same. With that said, the brass seemed to exhibit a just bit less pressure than H110, but not by much, and made up that pressure difference with just 0.5 gr more. Alliant 300MP looks like it should be just as good a powder for 300BLK as H110, and maybe a little better. It is very similar to H110. Of course more testing is needed. Especially to find a more accurate load. I would expect lowering the powder some would find a more accurate load at some point.


I've been shooting and reloading for 40 years, but this is the first time I've felt like I was walking into the unknown, with this 300 BLK. This is the first time I've ventured into such a new cartridge. It's an interesting experience. I'm doing my best to read the pressure without a pressure gauge, as we all are. I don't mind any constructive feedback if anyone thinks I'm way off the mark here. The last thing I want to do, is be unsafe.

What I am trying to do is settle down on some loads that are just a bit below the max, and are accurate. A little buffer room on pressure is not a bad thing.

With that said, I have not settled on any "favorite loads" yet.

Hope this helps. Be safe reloading.

[JohnInNH]

I have a huge jug of American Select so decided to load some subs for my Micro 7 with it again.. with the goal to come up with a load i do not have to weigh each time and use volumetricly. I ended up with a very consistent 1000 fps with a weighed 5.5 gr. A tenth up or down did not make as much a change as 231 which meters well too.

If i have a semi consistent powder position (not shaking muzzle down for one and one then muzzle up first) the fps spread was very good. The volume is about 2x that of w231.

This was a very nice fast easy way to crank out a 100 loads not having to weigh them all. Block fill with measure then visually inspect for a double or missing charge. A double would be at the top or maybe overfull .

Seems to be a cast friendly load. After 20 i checked my Mystic and did not have a lot of lead. An additional good subsonic load. The bolt gun is a real BLK friendly tool.

[Darkstang]

Took my 16" Noveske and some loads to the range today. VERY windy and that is what I wanted . Real world conditions. No chrono as I forgot it....
Hornady 300 whisper factory loads. 5 shots about 2.5" groups..
Sierra 125 smk ,18.4 H110, cci 450 . Show lots of promise . Less than 1.5" vertical but about 2.5 horizontal. VERY windy...Most were in a straight line left to right.

Lapua 123 fmj. Same load as above and damn near same group. I like these loads. Same point of impact.

150 Amax and 16 grain H110. No bolt lock back. Less than 2" group . Might go up on this load. Not as tight vertical as the other two loads but nice 1.75" cluster.

These were all 10 shot groups. Lots of three and four shot bugholes, but those dont tell the tale!

[vicpapa]

Can we sticky this thread?

[Maryland_Shooter]

what's the max chamber pressure for blackout?

55,000 PSI as measured with SAAMI techniques.

What would you suggest as a max PSI??????

my Quick load program is loading (50,763 PSI) as max I just don’t want to push my luck?

Thanks

Are you using Whisper or AAC 300 BLK because I don't see a BLK round listed.

Did you create a custom cartridge in QL?

[armed_zebra]

I was finally able to decide on a few loads and make enough of each to do some testing.

Noveske 8" Barrel with AAC SND-6
1/8 twist
Standard buffer

Subsonic load:

220 Sierra Match King
COAL 2.100"
Reformed LC brass trimmed to 1.358"
9.7 grains of Accurate 1680
CCI 400 Small Rifle Primer
No crimp

Average velocity of 50 rounds: 1060 fps (Right where I wanted to be)
Lo: 1007 fps
Hi: 1101 fps (Only 3 rounds were over 1080 fps, and not by much. 1087, 1086, and 1101. still quiet)
ES: 94 fps (Higher than I wanted but not dissatisfied with testing results overall)

Cycled the action perfectly and locked the bolt back on every last round. Pmags worked fine loaded to capacity in both the 20 and 30 round flavors. Grouped under 9" at 100 yards with an Aimpoint T-1.

Supersonic load:

Speer 125 TNT
COAL 2.050"
Reformed LC brass trimmed to 1.358"
19.2 grains of H110
CCI 400 Small Rifle Primer
No crimp

Average velocity of 50 rounds: 2030 fps
Lo: 1992 fps
Hi: 2060 fps
ES: 68 fps

Cycled the action perfectly and locked the bolt back on every last round. Pmags worked fine loaded to capacity in both the 20 and 30 round flavors. 7" group at 100 yards with an Aimpoint T-1.

[cconn]

Started working up a load today using the new 110 grain Barnes black tips. This is using LC once fired brass, loaded to the crimp groove. H110 powder.

18.5 grains, 2062, 2055, 2060, 2058
18.7 grains, 2048, 2048, 2043, 2053, 2044
18.9 grains, 2083, 2091, 2083, 2104, 2113
19.1 grains, 2103, 2100, 2085, 2084, 2097

Later I will load some more with higher powder charges and chrono them.

[loarpicker300]

Hey , everybody I've seen a lot of discussion re: subsonic loads, but what about accuracy. I'm down to 10.3 grains of A1680 behind Amax 208, chronos around 1080, but i cannot get below 1 moa ( using great bolt gun)
So what about accuracy at 100 yards in subsonic . Working up LilGun and N110 at present. Thinking about going to Hornady 195 match. Thoughts? (Schilling match barrel 1:10 twist)

[StonkerNZ]

Hey , everybody I've seen a lot of discussion re: subsonic loads, but what about accuracy. I'm down to 10.3 grains of A1680 behind Amax 208, chronos around 1080, but i cannot get below 1 moa ( using great bolt gun)
So what about accuracy at 100 yards in subsonic . Working up LilGun and N110 at present. Thinking about going to Hornady 195 match. Thoughts? (Schilling match barrel 1:10 twist)

240 SMK/2.220/9.6 W296

Max 1.094"/1.492 MOA
Average to centre .365"/.498MOA
Height .857" Width .680"

This was at 70 yds due to stock in the paddock; tikka T3 varmint rebarreled with 16", 1 in 8 twist.

Will hopefully be able to get out again to shoot at 100 and over in a couple of weeks and will post those results.

[loarpicker300]

StonkerNZ:
Any chronograph figures on that load?