Friday, April 13, 2018

April 13, 2018 -- A Quick Run Around The Web

  • Greg Ellifritz has posted this week's Weekend Knowledge Dump. A couple articles caught my attention in particular: one on the evolution of optics for the fighting/defensive rifle, and the other on being involved in a shooting around a car. On the latter topic, Ellifritz adds:
The idea that very few spots on the car offer true “cover” is somewhat misleading.  It depends on a lot of different factors.  Doors are not reliable cover, but if the bullet hits any of the latch or window mechanisms inside the door panel, it will stop.  The glass isn’t good cover, but you can stack the “A pillar” and the “B pillar” for very good (if narrow) protection.  If the car is moving, it’s damn near bulletproof.  You need to shoot up a few cars to really figure this stuff out.
I would add that it depends on the vehicle as well. I have an old (circa 1980) video called The Affect of Bullets that shoots up some of the old 1970s era land tanks that were considered family cars. The steel used for the body was much thicker than used today, and it showed because only a couple handgun bullets could actually penetrate a door. On the other hand, I was watching a video on YouTube recently testing bullets against a couple post-2000 manufactured cars, and even .22 LR was able to penetrate a door.
  • "Review: The Big Horn Armory AR500 : 3700ft/lb of Autoloading Power!"--The Firearm Blog. Using a modified .500 S&W cartridge, with the rim removed, Big Horn Armory has developed an AR capable of taking dangerous game, including African game. The rifle is based on a modified AR-10 upper and lower. The upper is modified to have a larger port to account for the larger diameter brass (the same as you need for an AR-15 shooting .458 SOCOM or similar sized cartridges). The lower is modified to accept a standard AR-15 size magazine (due to the shorter length of the cartridge). My question is: if the round can fit into a standard AR-15 magazine, why not use an AR-15 lower? Does the bolt require the extra length? Or could a shorter bolt have been used?
  • "Redefining the Terms: Tactics Of The Modern Day Anti-Gun Movement"--The Truth About Guns. The author notes that "[o]ver the past several years anti-gun legislators such as Diane Feinstein and Chuck Schumer, and anti-gun groups have repeatedly called some semi-automatic rifles ‘weapons of war’ and ‘military grade weapons’." And he notes that this language recently crept into the decision issued by a Massachusetts' federal judge upholding a ban on AR-15 style rifles.
  • I'm not sure it is worth the trouble: "HOW TO RELOAD STEEL CASE AMMO"--Guns, Holsters & Gear. I suppose if it was Boxer primed, it might be something to look at.
  • "Remington 870 DM – Follow Up"--Guns America Blog. The author reports that the magazines are holding up, and that you get use to the slightly different balance of the weapon.
  • "Guide to Gun Metal"--Rifle Shooter Magazine. The author goes into the history and some detail about the different steels, but also includes this summary:
Carbon Steels
  • 1020 and 1520—Common, “plain” or cold-rolled steel. You’ll find it in trigger guards, floorplates, sights, sling swivels and other steel hardware.
  • 4140—Ordnance steel or chrome-moly steel, it has 0.4 percent carbon and is really strong while still being cost-effective to machine. You’ll find this in barrels, bolts receivers and high-stress items like muzzle brakes.
  • 4150—The same as “ordnance” steel but with the carbon content upped to 0.5 percent. 4150 holds up better to serious abuse, and it’s found primarily in mil-spec AR-15 barrels.
  • 41V45—A chrome-moly variant, it has a dash of vanadium in it. This is an alloy selected to produce hammer-forged barrels.
  • 8620—This is a full-up alloy of nickel, chromium, molybdenum, with 0.2 percent carbon. Cast receivers are made of this alloy because it fills the mold well, machines cleanly and ends up very tough and strong.
    Stainless Steels
    • 316—Also known as “marine” grade stainless, as it resists corrosion well because of added molybdenum but is not easy to harden. Used in trigger guards and floorplates.
    • 17-4—An alloy with 17 percent chromium and 4 percent nickel. 17-4 (or a close kin) is readily hardened and is used in barrels, bolts and receivers.
      Aluminum Alloys
      • 6061—Aircraft aluminum, selected in that application for its light weight and ease of fabrication into complex parts. Floorplates on hunting rifles, scope rings and some handguards and buffer tubes on AR-15 rifles are made of 6061.
      • 7075—Much stronger than 6061, it’s the alloy used in AR-15 upper and lower receivers, some mil-spec brands of buffer tubes and some railed handguards. In mil-spec parlance, it is known as “7057-T6”; the last part designates the type of heat treatment it receives.
                The latest indication of fragmentation within the Jalisco Cartel New Generation (Cartel de Jalisco Nueva Generación — CJNG) came on March 25 in the embattled border state of Tamaulipas, when a splinter faction of the CJNG known as the Northwest Cartel allegedly got into a deadly firefight with Mexican Marines.
                 Officials say the Northwest Cartel is fighting the CJNG over control of a major drug trafficking route in Tamaulipas, a strategic area for criminal groups transporting drugs and other contraband into the United States.
                    The shootout follows news earlier this month that the CJNG may have murdered a former member of the group named Ramón Sánchez Radilla, alias “El Marro,” who reportedly belonged to a breakaway faction of the CJNG known as “El 2.”
            Illegal immigration declined significantly during the George W. Bush and early Barack Obama administrations, then stabilized at levels much lower than observed in the 1990s, though the latter Obama years seem to show some increase. But then in early 2017, there’s a huge dip: immigrants apparently just stopped coming. Within this dataset, deemed inadmissibility falls faster than apprehensions: inadmissibility peaks in October 2016, while apprehensions peaked in November 2016.
            He attributes this to fear over what the new President Trump would do. However, that fear has slackened:
                     But this effect has gradually worn off. As of March 2018, apprehensions and inadmissibles have risen to nearly 50,000 again, similar to the springtime-peaks observed during the Obama years. Whatever short-term effect Trump’s rhetoric may have had, with no actual new border security measures in place, it’s wearing off. Realizing that rhetoric has real, not quickly-fading, effects is probably motivating Trump’s decision to deploy the National Guard.
                       So when progressives say that we are at historically low levels of illegal immigration, the truth is that we were at historically low levels of immigration, thanks to a short-term Trump-led bust. But that effect is fading, and illegal immigration is rising again to the levels of the Obama administration. 
                          The Atlantic meridional overturning circulation (AMOC) — also known as the Gulf Stream system — is often described as part of the global ocean conveyor belt. It transports warm water from the Atlantic toward the Arctic, which influences the relatively mild climate of Western Europe.
                            In the northern Atlantic, this surface water eventually cools and sinks to the bottom of the ocean, where another current transports it south to Antarctica before circulating back to the Gulf Stream and beginning the cycle anew. This entire process is known as thermohaline circulation.
                              However, a team of researchers from University College London (UCL) and Woods Hole Oceanographic Institution (WHOI) have offered evidence from marine sediment that the AMOC is currently at its weakest point in the past 1,600 years.
                               Another study from the Potsdam Institute for Climate Impact Research (PIK) used climate model data and historical records of sea surface temperatures to reveal that the AMOC has been rapidly weakening since 1950 as a result of rising temperatures linked to global warming.
                                 Both studies, which will be published together in the April 12 issue of Nature, strongly suggest that the AMOC has weakened over the past by 150 years by at least 15 percent to 20 percent.
                          ... If the solar minimum has actually arrived now, this would make this cycle only ten years long, one of the shortest solar cycles on record. More important, it is a weak cycle. In the past, all short cycles were active cycles. This is the first time we have seen a short and weak cycle since scientists began tracking the solar cycle in the 1700s, following the last grand minimum in the 1600s when there were almost no sunspots.
                                    The big question remains: Are we about to head into a grand minimum, as happened during the Maunder Minimum in the 1600s? During that century there were practically no sunspots. Since it occurred immediately after the invention of the telescope, astronomers had no idea that the lack of sunspots were unusual and did not give it much attention. It wasn’t until the solar cycle resumed in the 1700s that they discovered its existence, and thus realized the extraordinary nature of the century-long minimum that had just ended. Unfortunately, it was over, and the chance to study it was gone.
                                      Thus, if a new grand minimum is about to start, it will be a once-in-a-lifetime opportunity for today’s solar scientists. Not only will they will get to study the Sun as it behaves in a manner they have not seen before, they will be able to do it with today’s phalanx of space-based observatories. The chance to gain a better understanding of the Sun will be unprecedented.
                                        Furthermore, the occurrence of a grand minimum now would help the climate field. We really do not know the full influence of the Sun’s solar cycles on the Earth’s climate. There is ample circumstantial evidence that it has a significant impact, such as the Little Ice Age that occurred during the last grand minimum, as well as the unusually cold climates that also matched past weak cycles, now, and also in the early 19th and 20th centuries. Studying a grand minimum with today’s sophisticated instruments could help measure precisely how much the Sun’s sunspot activity, or lack thereof, changes the climate here on Earth.

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