AR-15 Gas Block Diameter Explained
BY Herschel Smith3 years, 2 months ago
Ammoland covers the following.
I had never seen the Viking Tactics LUSA front Sling Adapter.
Which one do readers like the best, and what are you running?
Via WRSA, this thread at AR15.com is great. Thanks to the guy who worked so hard putting this all together.
I got it all the first time around (make sure to study all of the graphs and read the discussion carefully). If you’re unaccustomed to working with Newtonian physics, it may take you a time or two through it.
My complaint: He addresses only 55 grain bullets, and doesn’t seem to make much of barrel length. I’d like to see this thread expanded to include 68, 75 and 77 grains. A lot of guys are shooting heavier bullets now. That affects velocity, and thus changes everything.
But that’s a minor complaint. To be sure, I haven’t put together anything like this for readers, so I have no room to complain. I’m sure he put an awful lot of work into this, so he doesn’t need complaints from the peanut gallery.
A few odds and ends.
Via David Codrea, cops kidnapping children. Yes, seriously.
How to remove an AR-15 trigger group. Now do one on proper installation.
Removing an AR-15 barrel nut (hint: he heats it with a torch).
Rex reviews some really, really light Level IIIA body armor. Yea, it’s not good for rifle rounds, but it’s significantly less expensive and you’re protected against the most probable shot (and more likely to wear it given how light it is).
I had always wondered how easy or difficult this would be. It looks like it just requires some basic tools and a little patience.
I especially like that they got a gunsmith to explain it, and he provided pictures.
Whether a product is worth the price, recall from Mike Vanderboegh, depends upon what it can demand on the market. DD can demand this kind of money, and thus, they are worth the money – to a least enough buyers to keep them in business, and expand their business to become one of the largest AR-15 manufacturers in the game.
Most importantly, the new M16A1 came with a cleaning kit, lubricant and an entertaining field manual, drawn by Will Eisner, the former Army comic artist who designed vehicle manuals in World War II. It was called “The M-16A1 Rifle: Operation and Preventative Maintenance,” otherwise known as “Department of the Army Pamphlet 750-30.”
[ … ]
The comic was easy to read, entertaining and — above all — a familiar look to American GIs in Vietnam. Many of them would have been familiar with “The Spirit,” a comic about a Batman-like masked vigilante he created before the United States entered World War II.
By 1968, more American troops in Vietnam began to accept the use of the rifle as malfunction incidents decreased dramatically. The powder used in the 5.56 cartridge was upgraded to reduce the fouling of various parts of the weapon. By 1969, the M16A1 was fully accepted as the standard infantry weapon for the U.S. military.
I’ll bet if you had an original of this it would be worth a lot of money.
Combined with the current military M855, or even better the Designated Marksman “Match” ammunition, the M-16 platform can take us well into the new century. The military has decided just that by declaring that there is no reason to adopt any of the new weapon systems anytime soon. There are special units deploying ACRs (advanced combat rifles) but their chance at widespread use anytime soon appears to be zero.
Personally, I have tried most of this new generation of rifles and they are just bigger, bulkier and more complicated. Some are just downright ugly! I would take an M-16 style rifle over any of them.
Surprising to many, the “AR” is about 65 years old, older than almost everyone reading this, and it is still going strong. It is our longest-serving service rifle of all time, by a large margin, and every year it just increases that lead.
Almost every other country in the entire world has adopted the cartridge of the M-16, if not the entire M-16 itself, and those that haven’t basically copied it.
For a rifle that so many people supposedly hate, it has completely dominated the world. I am happy to be a fan and user of the “Black Rifle.”
I’m even prouder to be a citizen of the country that designed, adopted and fielded it with such success.
While I’m not a fan of the green tip ammunition, this is a fairly well-informed article and has good history as well.
To understand how we got here we need to look at its military origins. Some years ago I had the pleasure of meeting Eugene Stoner at the SHOT Show. We were able to sit down and chat for an hour or so, which I considered a privilege then and still do.
Back in the 1950s, he said, the U.S. military had just adopted the M14 rifle using the 7.62mm cartridge, ballistically similar to the .30-06. What might be called the “Old Guard” supported the concept of powerful battle rifles and carefully aimed fire at individual targets.
Other military theorists noted enemy soldiers for the most part don’t stand around in the open waiting to get shot. They hide behind things and shoot from cover. Combat in WWII and in Korea had shown the value of suppressive fire, “shoot and move,” and the integration of infantry, artillery and air power.
The rifle they wanted would be lightweight, with moderate recoil, selective semi- or full-automatic fire, compact and fast-handling for house-to-house fighting and adequately powerful, using non-expanding bullets. Hmmm, you don’t want much, do you? Stone said the only way he knew of to make a small non-expanding bullet behave like a bigger bullet is if it tumbles on impact. Original rifles had a 1:14 twist so bullets were just barely stable in flight, but would destabilize and tumble when they hit something.
Almost as soon as it was adopted the twist was changed to 1:12 to improve stability, which some argued also decreased effectiveness. In the ’70s and ’80s military users began shifting to heavier bullets for improved downrange ballistics, requiring faster barrel twists. It took a while, but faster twists eventually appeared on sporting rifles.
Faster twists and sleeker bullets, notably from Berger and Hornady, greatly enhance the versatility of the .223. Compare a 55-grain FMJ bullet (G1 B.C. 0.243) at 3,200 fps to a Berger VLD 80-grain bullet (G1 B.C. 0.455) at 2,750 fps. With both sighted at 200 yards, bullet drop at 600 yards is 91.5″ for the 55 grain versus 82.3″ for the 80 grain. Now check the 10 mph wind drift figures: 55 grain, 60.8″; 80 grain, 32.5″. That nearly 50 percentage advantage in wind drift is huge. Moreover the 80-grain bullet starting out 450 fps slower reaches the 600-yard line going over 400 fps faster (1,271 55 grain, 1,680 80 grain).
So what is a fast-twist .223 good for? Training with moderate recoil and noise. Teaching new shooters the fundamentals of center fire rifles and longer range shooting. Moderate cost due to smaller bullets and powder charges. Excellent hunting performance for most varmint shooting and for deer, the most popular big-game target. Untold millions and billions of .223 and 5.56 rounds have been loaded over the past 60+ years. Even in times of chronic shortages there’s a good chance of finding quality brass.
In my experience 1:9 will stabilize 70- and some 75-grain bullets, 1:8 will stabilize up to 80-grain bullets. Here’s some examples of twist rates in various rifles. The Savage Elite Precision is 1:7. Browning X-bolt, Ruger American, Sako 85 and Tikka T3X are all 1:8. Ruger’s Hawkeye, Howa, most Savage models, Kimber, Steyr and Weatherby Vanguard are all 1:9. Decide what your priorities are then buy accordingly.
I have heard that from multiple experts (i.e., that 1:9 twist barrels will stabilize 62 and 69 grain bullets, or even slight heavier like the Sierra Match King bullets).
I too and very fond of the round.
And I love hearing stories about Eugene Stoner. I think we ought to build statues of him and John Moses Browning as the premier weapons designers in American history.