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12.5 criterion and garmin velocity dump

Hoody2shoes

Sergeant of the Hide
Full Member
Minuteman
May 10, 2020
280
299
Temp around 65°

Cool air, warm sun.

Data was taken with garmin chrono

I tried to get groups but strong unpredictable gusts up to 30 mph in varying directions made it too difficult to isolate the ammo for consistent groups

Black hills 77 otm's red box. Unknown if this batch used the 77 sierra or the 77 hornady. All shot with suppressor. Data is avg of all strings. (3 strings 25 rounds)
High 2690 low 2622
avg 2649
Std dev 21
Ex spread 68

Black hills 69 TMK (only 1 string of 10 rounds)
High 2732 low 2683
Avg 2700
Std dev 18
Ex spread 49

Aac 75 gr w/o suppressor (1 string 10 rounds)
High 2600 low 2505
Avg 2554
Std dev 29
Ex spread 95

Aac 75 gr w/ suppressor. Avg of all strings (5 strings 50 rounds)
High 2647 low 2516
Avg 2557
Std dev 24
Ex spread 131

Now comes the part I was most excited about. I tested the badlands co 75 and 77 gr loaded in the Nas3 casings. These have given some really high velocities and I was hoping I would get similar. I was a bit let down.

75 gr w/ suppressor (4 strings 40 shots)
High 2738 low 2619
Avg 2669
Std dev 26
Ex spread 119


The 77's where similarly "slow" for what I had hoped for. (3 strings 30 shots)
High 2705 low 2571
Avg 2638
Std dev 28
Ex spread 134 (3 very low velocity shots)


If I exclude the low velocity shots I come up with
77's
Avg 2651
Std dev 18
Ex spread 84

75's
Avg 2675
Std dev 24
Ex spread 99

It should be noted that after taking out the shots that where much slower there were basically 2 velocities for the 75's. Most where within a few fps of 2650 OR 2700 the 77's didn't have the two distinct groups the 75's did.

*edit* spoke with the dudes at badlands. I called strictly to give data and feedback to which they didn't find the data satisfactory. They agreed the velocities were about 75 fps slower on average then they would have guessed (should have been about 2750) and they Ex spread should have been half. Long story short they will send me some new ammo to test when i get home from this upcoming deployment, none of which I asked for. That was really cool of them.

On a side note the Nas3 ammo was felt way less gassy than the aac ammo.

The last test was a poi shift when the suppressor is removed. My aac 75's (what it's zeroed on) shift .75moa left and 0moa vertically
 
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BMC 75 BTHP
- ES 111 / SD 25.9
AAC 77 OTM
- ES 61.9 / SD 14.6
AAC 75 BTHP
- ES 76.4 / SD 23.4

The last two sessions with AAC 77 OTM:
- ES 88.1 / SD 22.6
- ES 101.4 / SD 26 (Today 4.8.24)

 
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Ya thats rough with the massive ES from the bmc. I see so many others post such excellent velocities and consistent speeds and here we are with this crap.
 
OTM's would be Berger, no? Any idea what powder Black Hills uses? That seems smoking out of a 12.5" barrel. I think I get about 200fps less using TAC and the 77 grain OTM's on an accurate load. Might have to buy some and see how it does out of my barrel.
 
@Ape_Factory which otm's? AAC has stated theirs are made in house. I'm not sure but I get real good velocities from imi as well. I was hoping the bmc's would be around 2750. I've seen other NAS3 factory 77's pushing fast numbers in short barrels and hoped mine would do the same
 
I've been doing hand loads with Berger 77 OTM's. They label theirs with the "OTM" moniker so always thought that was their thing. Sierra usually refers to theirs as MK's or TMK's, Hornady has match, ELD Match, ELD-X, etc...I guess the ammo companies can call them whatever but always thought when they said OTM they were referring to Berger projectiles.
 
thanks for the data dump and most of all, the garnin.

been seeing some posts with garmins used as chrono’s and never looked into them, until now. what a cool set up but not cheap

my magnetospeed will get shelved. works well but can’t use it on some barrels and didnt want to use the old school design with screens.

$600 poorer today

as for ammo testing, here is mine from a 12.5” centurion barrel with the magnetospeed

aac 75gr black tip, 2500 ave

aac 77gr otm, 2450 ave

imi razor core, 2475 ave
 
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@Ape_Factory which otm's? AAC has stated theirs are made in house. I'm not sure but I get real good velocities from imi as well. I was hoping the bmc's would be around 2750. I've seen other NAS3 factory 77's pushing fast numbers in short barrels and hoped mine would do the same
With 75-77 grain bullets, I’m averaging 2630-2670 fps from my 16” barrel. 2750 would be SMOKING.
 
@PBWalsh the shell-shock casings supposedly work pressure differently. I've seen other data showing 11.5's getting better velocities than what I got. I've also seen consistent 2900fps from 18" barrels from various companies. I'm not saying my velocities are bad, but when black hills is doing the same thing with lower ES and SD I was a bit disappointed
 
2900 with heavier loading is still moving. I think I was hitting 2800ish with IMI 77 out of a WOA 20” barrel I had once.
 
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I'm not saying it's not moving lol. I'm saying the whole allure was these casings supposedly giving a large velocity bump without having any negatives. Maybe they'll figure out some powder stuff by late summer when I get a chance to test a new batch out.
 
Yes.

The BMC was similar to the BL in velocity but less gassy, less recoil, and had a more relaxed ejection pattern suggesting lower pressures
Sounds like faster powder. Hybrid cases aren't magic beans that grow velocity when you water them.
 
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Sounds like faster powder. Hybrid cases aren't magic beans that grow velocity when you water them.
Could be. I read somewhere the the larger internal volume of the casing allows for earlier combustion as well. I don't have the equipment to measure any of this unfortunately
 
Quite possibly. I'll give an update around August when I get home to compare.
 
damn thats a fast barrel. i have a new 12.5” centurion chrome lined thats is way slower with those ammos

aac 75gr saber black tip at 2500
aac 77gr otm at 2450
imi 77gr at 2450
federal mk318 at 2780
fusion 62gr at 2670

that was all with a xero c1, 3000 ft elevation and 80ish degrees
 
damn thats a fast barrel. i have a new 12.5” centurion chrome lined thats is way slower with those ammos

aac 75gr saber black tip at 2500
aac 77gr otm at 2450
imi 77gr at 2450
federal mk318 at 2780
fusion 62gr at 2670

that was all with a xero c1, 3000 ft elevation and 80ish degrees
And that’s faster than a midlength 12.5 Triarc I had with IMI 77 at ~2350-2375. But I feel IMI is slower than other loadings, need to test more of that though.
 
2900 with heavier loading is still moving. I think I was hitting 2800ish with IMI 77 out of a WOA 20” barrel I had once.
My records show averages in the high 2800ish with a Larue 20” suppressed, circa 2016/2017.
 
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