Here is a good page describing the essential components and design considerations in an AR-15 action. In this post I summarize some research I did focusing on the tail end of the system: The recoil spring and buffer. In order to see exactly what goes on in there I cut a viewport into a buffer tube, clamped rifles into my test fixture, and recorded high-speed video of the action cycling.Continue reading
I had the good fortune to meet Kyle Paaren, proprietor of Paaren Firearms, who specializes in rebuilding classic machineguns – often by rewelding demilitarized receivers. Many of these are brilliant pieces of engineering whose reliability and durability were proven in the mass military conflicts of the twentieth century.
I think the MG42 is the most impressive: It shoots full-power .30-caliber ammunition at a rate exceeding 1100 rounds per minute. It uses a roller-locked bolt mechanism that is unlocked by muzzle pressure (captured in its distinctive muzzle device) pushing back on the barrel itself. Its barrel can be changed in under five seconds.
I was allowed to take photos of some of these recent rebuilds.Continue reading
Here was my car’s fabric headliner before I repaired it:
After more than a decade, the original adhesive that holds the fabric to the backer that lines the roof of the car was failing. The headliner was detaching from the backer almost to the middle.
This is a common problem in aging cars. What’s going on? And how can we fix it?Continue reading
I’ve written a number of posts over the years in which I test the precision of various firearms. Some readers have asked about the particular methodology I use.
When testing guns for accuracy it is common practice to look at the Extreme Spread of a group of 3 or 5 test shots. I will explain why this is a statistically bad measure on a statistically weak sample. Then I will explain why serious shooters and statisticians look instead at some variation of circular error probable (CEP) when assessing precision.
Maple syrup is typically made by reducing maple sap by a factor of 40. For some time I was wondering what raw maple sap tastes like. A recent stop in a local grocery store’s Expensive Water section turned up quarts of Vermont “maple water” selling for $4.50! To satisfy my curiosity I bought one of these:
It smells something like diluted coconut water and tastes relatively neutral, with only a hint of sweetness and a woodsy aftertaste.
Of course the economics of this are crazy: A quart of Vermont maple syrup runs under $15. Why not buy maple syrup and dilute it with water, 40:1, thereby reconstituting “maple water” for a tenth the cost?
I guess you wouldn’t get the fancy packaging advertising the not-from-concentrate version’s “electrolytes, antioxidants and prebiotics,” some of which might be lost in the process of reducing sap to syrup?
Over the winter I accumulated a bunch of new factory ammo, and a few handloads, I was waiting for a nice day to test. That day finally came! Suffice it to say that with four rifles, two of which I switched in the field from .338LM to also test .308, this was an all-day affair. Now I need to find time to analyze all the targets and radar data….
This Remington R51 is a really great gun. I bought it at the end of 2017 for $500 (including the Crimson Trace laser sight) while Remington was offering a $100 mail-in-rebate. I have to applaud Remington for going through the significant trouble of launching a pistol based on the Pedersen “hesitation lock.”
Previously, pocket guns with such a low profile were only available with simple blowback actions, which limits them to .380ACP or lighter cartridges. The R51 is rated for 9mm +P, which puts it in the realm of “full-power” defensive handguns. At one time I owned a Sig P232, which is a very slick .380ACP pocket gun, but I sold it some years ago during a caliber consolidation. Subsequently my only gun that really fit a pocket holster was the S&W 642 revolver. Lacking the cylinder bulge, the R51 is easier to carry in a pocket. If you’re looking for an “everyday carry” gun, you could end your search here on that basis alone.
I have never leased a car for myself, but since interest rates crashed a decade ago I have considered it several times. (I generally prefer to buy new cars, and when you have cash to cover the purchase one drawback to leasing is that you have no choice but to pay interest on the residual value of your lease for the full term of the lease. With lower interest rates that’s a less significant cost.)
I just helped another friend arrange a lease and realized I haven’t published my guidance on this. Since dealers often use the complexity of lease contracts to pad their margins, here’s all you need to know to cut through the charade:
The three numbers that matter in a lease
1. Purchase price. This is pretty much the only thing you can negotiate. Unless the car you want is in extremely high demand, you should demand the dealer set the “sale price” no higher than dealer invoice minus any factory discounts currently applicable. (If you’re a good negotiator, or you hire one, you can often get the dealer to sell below invoice. But invoice is usually considered “fair.”)
While dealers try to mix the two to confuse buyers and increase their profit, the lease agreement is done after you have a purchase agreement. (You can actually shop around for financing, but whenever I have checked I have found the best lease terms come through the manufacturer’s finance arm, which means you’ll probably end up talking to the same dealer about the lease agreement.) This is where the other two numbers that matter come up:
2. Residual value. This is entirely a function of how long you want the lease to run and how many miles you want to be allowed to drive. Usually the best residual values are given for standard leases (e.g., 36- or 39-month with 12k or 15k miles/year.) But sometimes manufacturers want to push other lease terms to control their resale inventory, so if you’re flexible it’s worth asking about those.
3. Money factor. This is the interest rate you are paying (quoted, oddly, as the annual rate divided by 24). This is almost entirely a function of your credit score. But often a higher initial payment can reduce this, so if you have cash available you should look at options to reduce the money factor by increasing your up-front payment. (In the limit you can pay the full cost of the lease up front.)
This was a strange one to debug: I upgraded the LED bulbs in my garage door openers from 60W to 100W (equivalents). My wife’s garage door uses a track-mounted motor head with a lightbulb on each side. She began reporting that she couldn’t close the garage door after she pulled out. After some investigation using multiple transmitters we confirmed that it would reliably open from up to 100 feet away, but it would only close using the remote transmitters if they were within about 15 feet of the receiver, which is in the motor head … next to the lightbulbs … which are turned on by default when someone is in the garage or crosses the threshold, but usually off when approaching the garage from the outside with the door closed.
So the newer LED bulbs I installed were unintentionally serving as garage door opener jammers!