14.5" AR upper

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Netpackrat
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Re: 14.5" AR upper

Post by Netpackrat » Tue Jan 22, 2019 9:38 pm

Precision wrote:
Tue Jan 22, 2019 9:26 pm

I hear your point. But if they get into it at a traffic stop,they have violated a Bill of Right by searching. That dramatically ups the pay out.
Precisely but not even the whole of it. A keyed lock, and he just uses the key to open and take your stuff. He isn’t getting past the combination lock without either beating the combo out of you or breaking in. Or if they try to charge you with something, either way you have given your lawyer a lot more to work with.

Also, I can always get a new truck gun. Can’t get a do-over if I died because all I had was an ultra low capacity weapon with limited ability at range.
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Precision
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Re: 14.5" AR upper

Post by Precision » Thu Jan 24, 2019 4:20 pm

Netpackrat wrote:
Tue Jan 22, 2019 9:38 pm
Precision wrote:
Tue Jan 22, 2019 9:26 pm

I hear your point. But if they get into it at a traffic stop,they have violated a Bill of Right by searching. That dramatically ups the pay out.
Precisely but not even the whole of it. A keyed lock, and he just uses the key to open and take your stuff. He isn’t getting past the combination lock without either beating the combo out of you or breaking in. Or if they try to charge you with something, either way you have given your lawyer a lot more to work with.

Also, I can always get a new truck gun. Can’t get a do-over if I died because all I had was an ultra low capacity weapon with limited ability at range.
good points too.

Gotta get the new to me truck first. Guaranteed it won't fit both.
"Those who hammer their guns into plows will plow for those who do not." ~Thomas Jefferson
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Precision
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Joined: Wed Aug 20, 2008 6:01 pm

Re: 14.5" AR upper

Post by Precision » Fri Jan 25, 2019 12:21 am

school me on the effective difference between an 8.5" and a 10.5" barrel for 300 BLO. I assume not much for heavy subsonics. I assume a bit of velocity for supers?
"Those who hammer their guns into plows will plow for those who do not." ~Thomas Jefferson
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Netpackrat
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Re: 14.5" AR upper

Post by Netpackrat » Fri Jan 25, 2019 12:38 am

I think the original spec that Robert Silvers of AAC submitted to SAAMI called for a 9" barrel, and that was the length of AAC's pistol/SBR uppers and barrels in that caliber. That submission also specified a 1 in 8" twist but everybody is using 1 in 7" now because it was found that an 8" twist will not reliably stabilize bullets heavier than 220 grains. My own SBR uses an Aero Precision 10" upper. A friend that spent more time looking at velocity charts than I did settled on 12" for his hunting SBR in BLK, because of diminishing velocity returns beyond 12 inches. If you want to run subs you may find them going supersonic in the longer barrel lengths, as I did with my 16" bolt action.

Here is some chrony data that I posted to another forum back in August. Weather was sunny and mid 60s, range is basically at sea level:
Made it to the range with both of my 300 Blackout rifles last week, and went to the trouble of dragging along my chronograph and setting it up. Collected velocity data with all of the Blackout ammo that I had on hand with both rifles. One thing that the data really showed, is if I want to run subsonics in my bolt gun and have them actually stay subsonic, I am definitely going to have to handload. I was planning on doing that anyway, but I had hoped at least one factory load would be slow enough.

I saw a little less loss going from the 16" barrel to the 10" barrel than I expected, particularly considering the SBR is gas operated, so that was cool. The clear velocity winner among the supers was the Hornady Black, but they also seemed to not group as well as the Barnes. It was a horrible day for shooting groups given the gusty wind and the sun directly downrange, but the Barnes was definitely a little better than the Hornady once I moved out to 100M. The UMC (also loaded by Barnes) was consistent as usual, and the PRVI was a shit show accuracy wise from both rifles.

As follows is my raw chronograph data and average velocity of each load from both rifles. Anybody who wants to plug it into a spreadsheet and get the standard deviation, etc, can feel free but I am not going to bother:

Remington Model 7 300BLK
Bare action build with 16" AAC Barrel
Unsuppressed

Nosler 220 grain subsonic 51275

1060
1123
1132
1099
1140

AVG 1111 FPS
---

Herter's 220 Subsonic HRT300BLKSUBA

1113
1078
1127
1114
1094

AVG 1105 FPS
---

Sig 220 Subsonic E300A2

1089
1114
1112
1111
1099

AVG 1105 FPS

Remington 220 Subsonic (green/yellow box) R300AACB

1092
1157
1088
1127
1121

AVG 1117 FPS
---

UMC 120 L300AAC1

2305
2325
2355
2350
2344

AVG 2336 FPS
---

Barnes 110 (black tip) BB300AC1

2375
2394
2388
2395
2396

AVG 2390 FPS
---

PPU 125 HPBT

2248
2238
2242
2255
2243

AVG 2245 FPS
---

Hornady Black 110 VMAX 80873

2508
2535
2525
2555
2537

AVG 2532 FPS
---

Aero Precision 10" 300BLK Upper
Aero SBR lower
Unsuppressed

Nosler 220 grain subsonic 51275

993.3
1008
1011
1008
1010

AVG 1006 FPS
---

Herter's 220 Subsonic HRT300BLKSUBA

1025
964.6
977.4
983.6
991.3

AVG 988 FPS
---

Sig 220 Subsonic E300A2

947.4
977.8
969.6
964.8
959.8

AVG 964 FPS
---

Remington 220 Subsonic (green/yellow box) R300AACB

1000
1009
1023
1038
1037

AVG 1021 FPS
---

UMC 120 L300AAC1

2170
2151
2161
2149
2139

AVG 2154 FPS
---

Barnes 110 (black tip) BB300AC1

2212
2196
2190
2180
2208

AVG 2197 FPS
---

Hornady Black 110 VMAX 80873

2295
2333
2327
ERR
ERR

AVG 2318 FPS
---

PPU 125 HPBT

2085
2074
2070
2078
2031

AVG 2068 FPS
---
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Precision
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Re: 14.5" AR upper

Post by Precision » Sat Jan 26, 2019 8:34 pm

So if I read your info properly, for a handloader running subs, no real difference between 8.5 and 10.5".

When running supers, it (powder burn rate dependent) might be 100fps difference. All told, not likely a big deal at sub 100 yard distances.

I am looking at a Complete upper less BCG and Charging handle for $190. Almost can't afford NOT to buy it. Ratings and reviews seem good. I have a spare BCG, a CH, and several stripped lowers. Just need a lower parts kit, upgraded trigger and I am done. Total of $300 from here. Not bad. Maybe $450 all in.
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Netpackrat
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Re: 14.5" AR upper

Post by Netpackrat » Sun Jan 27, 2019 3:51 am

Sounds like a good deal. I am probably going to put together an AR pistol in Blackout for a truck gun at some point in the not too distant future as well. I bought a used 8" Noveske barrel locally and plan to build it using the Dolos take down system and a LAW folder. I'd kind of rather have an AK for that use, but configured thusly I can get an AR to stow in a much smaller space, so I will hold my nose and build another AR. I have a second lower that I SBRed but I am not willing to use an NFA weapon as a truck gun, and Alaska is one of those states that only allows you to carry a handgun concealed.
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Precision
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Re: 14.5" AR upper

Post by Precision » Sun Jan 27, 2019 11:05 pm

Netpackrat wrote:
Sun Jan 27, 2019 3:51 am
and Alaska is one of those states that only allows you to carry a handgun concealed.
That is DUMB. I thought Alaska was an open carry state. Oh well, so long as you know the rules...
In a lot of ways TN is better than Florida, especially since FL passed the red flag laws. Ughh. But the no chambered rifle in a vehicle law is just absurd.

I figured you would prefer an AK, but even with it SBR'd and side folder, it is significantly bigger than an AR?
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Netpackrat
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Re: 14.5" AR upper

Post by Netpackrat » Sun Jan 27, 2019 11:38 pm

Precision wrote:
Sun Jan 27, 2019 11:05 pm
That is DUMB. I thought Alaska was an open carry state. Oh well, so long as you know the rules...
In a lot of ways TN is better than Florida, especially since FL passed the red flag laws. Ughh. But the no chambered rifle in a vehicle law is just absurd.

I figured you would prefer an AK, but even with it SBR'd and side folder, it is significantly bigger than an AR?
Oh, it is. But if I want to carry concealed, I have to do it with a handgun.

This is how I can make an AR pistol stow in a significantly smaller space than an AK:

https://www.youtube.com/watch?v=emxYX8U2yHk

Edit to add; Alaska used to have the no loaded rifle in a vehicle thing, but I think that went away years ago in either the first or second round of improvements to the CCW laws (the original permit law had a lot of bullshit in it).
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Precision
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Re: 14.5" AR upper

Post by Precision » Mon Jan 28, 2019 3:37 pm

TN has the handgun only for concealment too. Kinda sucky but simple physics makes concealing a rifle a bit more difficult.
"Those who hammer their guns into plows will plow for those who do not." ~Thomas Jefferson
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