RFID-Blocking Wallets

When it comes to vitamins, minerals, and other dietary supplements, I have a category of “Not harmful, likely helpful” for things that have no obvious downsides and some potential benefits. When it comes to your personal information hygiene, RFID (Radio Frequency IDentification) blocking wallets/sleeves fall under that same category.

Cash is the “network independent” form of currency, but digital currency has largely become a very widely accepted form of “settling a debt.” This can be done using a physical token such as a credit or debit card, or through a smart device linked to your banking information. If you see “tap to pay” on a gas pump or payment terminal, you are seeing a near field communication (NFC) capable system. 

Because debit/credit cards or “pay by phone” requires a communication from the terminal back to the financial system to do all the accounting, if the network goes down, you can’t pay with  that digital currency. This means that cash is going to be part of the “right mix” of resources for prudent prepping. For example, I was recently at a gas station while a thunderstorm rolled through and severed the satellite link from the station to their payment processing provider. Having cash on hand allowed me to purchase fuel, while other patrons sat around and waited for the network to come back up.

However, carrying around enough cash to pay for everything all the time is problematic from a risk standpoint, as people with lots of cash tend to get targeted. There is a place for “digital, network dependent currency” in a prudent lifestyle. Reduction of risk for being targeted for your cash means accepting the risks associated with using digital currency, and the hope that the networks necessary for financial transactions stay up.

How much actual risk is there from a “tap to pay” payment? Any communication that goes over radio frequency is subject to reception by an unintended party. The stronger the signal, the further away unintended parties can listen in; the weaker the signal, the closer they need to be. Luckily, NFC communications are very weak, and so all demonstrated attacks require the listening device to be within yards, if not feet, of the targeted area. 

 Although I know of no instance where RFID skimming has occurred “in the wild” for monetary theft, I still use a radio frequency blocking wallet to hold all my “smart cards” for personal or work use. There are a lot of options on Amazon, but this is the make and model I’ve used for the last several years. I also keep my “smart passport” in an RFID-blocking sleeve similar to this. On the other hand, I also know that penetration testing teams routinely capture NFC signals to clone identification cards, and if penetration testing teams do it, it is the most likely bet that other organizations do it as well for less noble purposes than security testing. Therefore I protect my information with RFID blockers, and this gives me a bit of peace of mind in airports and similar locations.

This does not eliminate all my risk, but between a bit of cash and a bit of digital currency, the biggest risk remaining is simply losing my wallet. Much like I take a daily multi-vitamin because it is “Not harmful, likely helpful”,  I make sure I use an RFID-blocking wallet.

So if you need a new wallet, or are purchasing a gift for a young person about to embark on the start of adulthood, an RFID-blocking capability is a very nice feature. 

Prepper's Armory: Ammo Mishaps, part 2

In my previous post on this topic, I discussed what can happen to guns when the wrong ammunition, or ammunition loaded to excessive pressure, is fired in them. In this installment, I'll look at ammunition which, while having similar external dimensions, are actually two distinct cartridges.

One that’s not heard about as much today is the .38 ACP chambered in early Colt semi-automatic pistols. The original loading of .38 ACP had very similar ballistics to .38 Super, enough to damage the firearms of the time, and so the cartridge was reduced in power. However, the later-designed .38 Super has nearly identical case dimensions and can be chambered in those older guns. Modern .38 Super fired in antique .38 ACP pistols can damage the gun and possibly even injure the shooter.

Similarly, the older 7.63 Mauser and more recent 7.62 Tokarev are nearly interchangeable as to external dimensions, but their current loadings are not comparable in power. I had the misfortune of being shown a pre-World War I C-96 Broomhandle Mauser that had been fed a regular diet of 7.62 Tokarev rounds. The shooter hadn't been injured, but the gun was ruined.

Data from Hornady Handbook of Cartridge Reloading

Another common issue of concern is military surplus rifles being rechambered in cartridges well beyond their pressure limits. Years ago, Bloke on the Range participated in a video about a Short Magazine Lee Enfield rifle rechambered for 7mm Remington Magnum. 

Understand that .303 British, the original chambering for the SMLE, has a maximum pressure of 49,000 psi according to the Sporting Arms and Ammunition Manufacturers Institute (SAAMI) standards. British and Commonwealth arsenals use intentionally overloaded ammunition called proof cartridges to certify firearm safety. These generally develop around 10% over maximum pressure of a standard round, or approximately 54,000 psi in the case of .303 British. In comparison, the 7mm Remington Magnum has a 61,000 psi maximum. That’s a 12,000 psi increase over a standard pressure cartridge! By the end of the video, the rifle was not in good shape.

Data from Lyman Reloading Handbook

There are also military rifles that were rechambered during their service lives due to a change in the issue cartridge. For example, right around the turn of the last century, the German military changed their standard cartridge from the Patrone 88 to the S Patrone. The cases were nearly identical, but the bullets differed in shape, weight, and most importantly, diameter.

The Patrone 88 fired a .318 inch bullet at around 2,100 FPS. The later S Patrone was a .323 inch bullet that traveled at nearly 2,900 FPS. Now, .005 inches may not sound like a lot, but we are talking about a significant pressure increase in rifles over a century old at this point, the earliest of which were originally designed for black powder.

Data from Lyman Reloading Handbook

In fact, unless the owner really knows what they're doing, some of these early rifles probably shouldn’t be fired at all. The new (or rechambered) barrel should have the current chambering stamped into it, but this isn't always done. If the chambering of a rifle is in question, a chamber casting can be made for proper measurements.

There are other examples, but I hope by this point the message is clear: know the firearm and its appropriate ammunition. As mentioned previously, a good resource is SAAMI, the Sporting Arms and Ammunition Manufacturers Institute.

Be careful, be safe, and enjoy many more years of shooting without blowing up any guns.