This is an excerpt of an article that appeared first in the January 2021 Issue of Muzzle Blasts Magazine. Join the NMLRA Today to receive this great publication.

The Bevel Brothers 

Worth Another Look Dept.: Back about 20 years ago we wrote about how some depleted uranium called D-38 had somehow worked its way into retail commerce in the form of flintlock frizzen facings. As far as we can tell, the stuff had been sold in thin sheets by somebody in Florida for use in re-facing flintlock frizzens back in the 1970’s or 80’s. We’ve got a pretty good idea who it was, but at this point there’s no point in disparaging the dead, so we’ll just leave it at that. The stuff produced a much more vigorous spark bundle with an impressive shower of white hot sparks even with a dull flint.

Trouble was, and is, this D-38 stuff is actually pretty dangerous to use in places where it’s likely to get dusted into the air the way it does on a flint frizzen.

Bevel Up: We wrote up an article about the stuff and how dangerous it is, but like much of what gets written in a monthly periodical, the long term impact of such a warning is limited. We either get asked or hear about somebody using this stuff occasionally and as it happens just last week a guy in California called me up to ask about an old gun he had inherited. It was a flintlock that his uncle or cousin or somebody had used when he was “re-enacting” back in the 80’s. Seems like that’s happening more and more frequently now as the muzzleloading guys from back in the early days of the revival age out. It’s just another reminder of how time slips away as we wander through life’s rich pageant. But I digress.

So, from the description the caller gave it sounded like it was a modern made rifle from the 70’s or 80’s but the lock wasn’t marked so he couldn’t tell who made it. He said that the rifle didn’t look to have many miles on it, but it already had a re-faced frizzen. That seemed sort of suspicious to him and to me. I told him what I thought the frizzen might be and that he should get it checked out (more about that later).

You can generally tell that a frizzen has been re-faced just by looking at it. It will have an extra layer of steel either soldered or riveted with little pins onto the face of the frizzen. Mind you, not every re-faced frizzen is dangerous.  There are lots of them out there in circulation – antique and modern – that have worn frizzens with a new carbon steel face on them. But it takes years of use and many hundreds or even thousands of shots to wear out a modern frizzen. This is especially true with frizzens like you see on the Siler, Chambers, Davis, and L&R locks we put on custom rifles. Those modern frizzens are solid steel all the way through, so they really don’t ever run out of steel and stop sparking. But after many thousands of shots, a modern frizzen may become so worn down that the lock geometry has changed and it needs a new face to bring it back to optimum performance, or it might wear down so thin that it cracks or breaks, but that’s not because it has worn off the carbon steel that makes the sparks. And, having refaced a couple of frizzens in my time, I will say that it’s way easier to just buy a new frizzen than to fool around with riveting and soldering and heat treating a piece of steel onto an old one. Of course, sometimes – especially with old or antique or uncommon locks – you can’t buy a new frizzen that fits, so you have to renew the face.

Bevel Down: We’ve been aware of this D-38 showing up on frizzens for quite a few years. The first we heard of it was in an article in the August, 1992 issue of Muzzle Blasts written by John Meisenheimer and C.E. Laird. Then, be-cause we kept hearing about the stuff, we wrote an article about it again back in 2000.

I did a little research on the subject and found out that D-38 is another name for U-238, which is natural uranium that has had the U-235 isotope content reduced from about 0.7% down to about 0.2%. U-238 is essentially a waste product of uranium enrichment plants that make the high-powered stuff (U-235) for nuclear bombs and nu-clear reactors in power plants and subs and what have you.

D-38, or U-238, is a low level radioactive material. It has a half-life of 4,470,000,000 (that’s four billion, four hundred seventy million) years! It has been employed by civilian industry in applications where a really heavy metal is needed (the stuff is more than half again heavier than lead and about two and a half times heavier than iron). The military uses it to make armor piercing rocket and artillery ammunition for use against tanks.

Apparently, this stuff is relatively safe to be around and even handle in its normal, solid state. By that I mean that it doesn’t just sit there emitting huge amounts of radio-active death rays, anyway.  The problem comes when it is fractured or “aerosolized” as a result of either machining or milling to shape it into a useful object (civilian uses), or as the result of an explosion (military uses).

By the way, “aerosolized” is a term I picked up in this research – sort of a made up pseudo-word, I think, that means the stuff has been turned into really fine dust and sprayed into the air. Anyway, when this D-38 metal fractures, it breaks off into tiny little pieces and particles that give off an unusual amount of heat, which is part of why it works so well against the armor on tanks. It is also why it works so well on frizzen faces. The sparks that a flintlock throws are really just tiny pieces of the steel frizzen that get scraped off by the flint and turn white hot in the process. That’s what makes the powder in the pan ignite. D-38 just gives off way more and way hotter sparks, so that’s why it appears to be working so much better than a regular carbon steel frizzen. So going back to that aerosolization problem (which is ex-actly what happens when a flint hits a frizzen face) what happens is that these tiny (microscopic, even) bits of U-238 that the flint scrapes off contain particles that give off alpha, beta, and gamma radiation. There are also some other toxic elements in that cloud, like radon and radium that nobody should breathe if they can help it.

The way a flintlock works is that the flint strikes the frizzen face and scrapes a bundle of little white-hot shards of carbon steel off the frizzen and dumps that bundle into the prim-ing powder there in the pan. When those sparks ignite the priming pow-der a cloud of gas, burnt powder, and what’s left of those little pieces of frizzen rise up within a few inches of your face.  Sometimes if the wind is wrong it comes right up into your face and inevitably you will breathe in a whiff of two of that mélange with every shot.

So if you’ve got this U-238 frizzen face instead of a regular steel one, what was formerly a relatively benign piece of U-238 attached to your flintlock has become a mist of radioactive atoms that have entered your body through your mouth, nose, and eyes.  And being a heavy metal, those radioactive particles will tend to gather and settle in soft and vulnerable parts of your body, such as your eyes, lungs, liver, and kidneys where they can slowly cause permanent damage and create cell mutations that may someday turn into cancer. Plus, getting too many particles of this stuff trapped in your body can give you a lifetime overdose limit of radiation in just a short time. How many is too many, I don’t know, but for my money, zero is a good number.

Bevel Up: But you don’t really need D-38 sparks to set off a few grains of black powder in your pan. Any good lock with a reasonably sharp flint will give you way plenty more sparks than you need for that job. It’s worked that way just fine for about 300 years and really doesn’t need any 21st century improvement to keep on working.

Bevel Down: And you need to consider that even if you have a personal death wish, or think that you are somehow immune to this kind of radiation poisoning, every time you touch off a shot with this stuff, you send a puff of the stuff into the air that everybody around you is breathing, too. The exposure extends to you and all the shooters around you, and anybody standing downwind of you, and anybody who handles your clothes or your rifle or any of your gear afterwards. Thus, everybody downstream of this lock gets exposed to these tiny, tiny, microscopic-sized bits of U-238 radioactive material.

So here’s our question for all you folks out there in Read-er land:  Is a really sparky lock worth absorbing radioactive bits of U-238 every time you touch off a shot? Is it worth it to your family, friends, and neighbors? We think not. We hope you agree. Bevel Up: So, back to that 80’s vintage flintlock that I told you about.  I more or less told this caller what we just told you folks. So a couple of weeks later he called back and said he’d had the lock tested with a Geiger counter and that the frizzen face wasn’t radioactive U-238 after all.  

So who knows why the owner of that lock re-faced it.  There were, and are, a lot of shade tree gunsmiths roaming around muzzleloader shoots and rendezvous, so it may have been somebody’s attempt to “fix” a frizzen that really just needed to be properly heat treated, or it might have been done in the mistaken belief that after so many shots it needed to be done to keep it sparking good.

But like we said, a properly made and heat treated modern frizzen shouldn’t need to be refaced unless it is severely worn. But, having said that, I will direct you to the picture of a brand new lock that I did have to re-face because it just absolutely would not harden enough to spark. It’s a copy of an original Ketland that was produced in a small run some years ago. I got it through the Museum of the Fur Trade in kit form (basically a box of castings). I don’t know what kind of steel it was made from, but it just absolutely would not give a spark until that frizzen was re-faced with a piece of high carbon steel. Dale Johnson re-faced it for me using a piece of steel out of a big sawmill band saw blade (you can contact him at 610 Swimming Pool Road, Hampton, TN 37658). It works just fine now.

Bevel Down:  If you have a lock that you suspect has one of these depleted uranium frizzen faces installed on it, you can find the radiation control agency for your state by going to the website of the Conference of Radiation Control Program Directors at https://www.crcpd.org/mpage/Map.  They should be able to help you get it tested and dispose of it properly if it turns out to be radioactive.