I believe I have made a little progress in addressing the problem of slow ignition delays when using black powder substitutes in flint lock guns.
The use of black powder substitutes in flint lock guns has been a problem from the very introduction of black powder substitutes. In fact, not only in flint lock guns: Percussion weapons suffered the same fate; this to the extent that the hotter 209 primer system was introduced. The later re formulation of BP substitutes have largely addressed the issue in regard to percussion arms; but the problems with its use in flint guns remain. Users complain of slow ignition times between the detonation of the prime and the ignition of the main charge and a higher incidence of ”˜failure to fire’ (flash in the pan). These problems lead to inaccuracy and while this can be tolerated during plinking and re enactments; the use of flint guns with ignition problems have no place on the target range and neither in the hunting field.
The free availability of black powder is becoming problematic throughout the world. Even in the United States, users complain of the difficulty in obtaining stocks of black powder; having to travel long distances to obtain stocks of powder and at great expense. On the other hand, black powder substitutes are freely available and; given the ongoing restrictions being placed on the availability, transport and storage of black powder, this situation is not going to ease in the near future.
In South Africa, the problem is even more severe: Very little black powder is imported and if it is available, the cost is astronomical. Our local substitute: Sannadex, while giving good service in percussion guns, suffer from the same ignition delays and misfires when used in flint lock rifles.
One solution in addressing the use of substitutes in flint guns; is to use ”˜booster’ charges of normal black powder; loaded ahead of the substitute powder. In my own experiments with large bore (.58 cal and larger) guns, I have found that reliable (fast) ignition is achievable when using booster charges; but these booster charges should be at least in the order of 20 ”“ 25gr of black powder. In addition, the main charge must be reduced with the amount of booster used; so as not to exceed the recommended load for that particular barrel/bullet.
Booster charges give rise to two problems. One, it requires relatively large amounts of black powder which is in critically short supply and two; you need to carry an extra flask of powder afield. While not a problem on the range; it does become a problem in the hunting field.
In trying to reduce the amount of black powder needed for a booster charge, I experimented with combustible paper powder cartridges; where a small amount of black powder (10gr) is loaded, followed by the main charge of substitute powder. This proved to be marginally successful. In guns where the vent (flash hole) is situated at the very bottom of the breech face (internal), a smaller amount of booster could be used. But, in barrels where the vent is a little further away from the breech face (like in most commercial flint lock guns), the amount of booster used must be sufficient to, at least, cover the vent. In addition, this paper cartridge must be punctured through the vent; this to allow the booster to migrate to the flash hole.
To my view, this was only a partial solution. In some guns; you will get away with using a 10gr booster charge; in others, a far higher booster charge is required ”“ which defeats the purpose (of conserving BP) somewhat.
There had to be another way ”¦
Research on the internet shows that black powder has an ignition temperature in the region of 300 ”“ 350F. Some sources claim a far higher ignition temperature; this in the order of 570F (Reliable data on both black powder and its substitutes is incredibly difficult to obtain.) Black powder substitutes, on the other hand, has an ignition temperature in the order of 700F and higher. Based on these figures alone, black powder should not be capable of igniting BP substitutes! But, black powder has a burning temperature of about 1700F, depending on the granulation used. So, BP will reliably ignite substitutes; but with a delay in ignition; caused by the time taken for black powder to reach the ignition temperature of the substitute powder. Now, this is a very small time delay and normally, will not be noticed; except when using high speed recording equipment.
But, in addition to the ignition delay; the heat of the burning black powder must also navigate the vent (flash hole) and here a completely different set of rules comes into play. For instance, when using black powder only in a flint gun, it is the radiant heat from the prime that ignites the main charge of black powder. In fact, it is recommended that the prime not cover the vent and that the main charge not fill the vent from the inside; but forms a little channel to ensure reliable and fast ignition.
But, substitute powders will not ignite from radiant heat alone.
Now, we are fortunate that our Sannadex (SDX); either the Rifle or Pistol granulations, will ignite when used as the prime in a flint lock. Ignition is hotter (whiter flame v the yellower flame of BP) than black powder, but the burning rate is observably slower. Thus, using SDX as a prime slows ignition substantially; with frequent misfires.
So, I tried a prime mix of 50% FFFFg and 50% SDX Pistol. These two compounds mix reliably and stay mixed. Ignition time is now as fast as an FFFFg priming powder, but much hotter; thanks to the SDX’s higher burning temperature. So, now I had a priming mix hot enough to reliably ignite a substitute powder.
Tests showed an improvement, but still not as fast as a BP prime and main charge.
A little further experimentation showed that the way the prime is banked in the pan needs to be changed, as is the loading of the substitute powder main charge. Instead of banking away from the vent or below the vent, the prime should now touch the vent. In addition, the main charge of substitute powder should fill the vent from the inside: In fact, if you can see a little granule of substitute powder peeking through the vent at you, so much the better. In addition; because combustion is now taking place in the vent, cleaning the vent (with a vent pick) after each shot becomes mandatory. (This will probably place additional wear on the vent; necessitating its later replacement.)
But, ignition is fast; as fast as with a BP prime and main charge: or within the parameters that I can observe without specialist measuring instruments.
At the range yesterday, my son in law (I took him and my daughter shooting flint guns) recorded videos of the flint guns firing with the ”˜new’ priming mix and a SDX-R (Sannadex Rifle Grain) main charge. Now, these were cell phone videos recorded at 30 frames per second. Back at the shop, I was able to review these video clips using a freeze frame facility and the results were quite interesting:
It takes 3/30th of a second (3 frames) for the cock of a Chamber’s lock to move from the cocked position to where the frizzen is knocked open. (The Brown Bess lock takes 6 frames.) The next frame (frame 4 or 4/30th of a second) shows the prime already igniting (flame). In frame 5 (5/30th of a second), the priming flame grows and the gun starts moving back in recoil; indicating that the main charge is combusting while a small amount of smoke is issuing from the muzzle (combusting powder overtaking the ball/patch?). In frame 6 (6/30th of a second), the main volume of combustion smoke has exited the barrel and the rifle is still rising in recoil.
If one can draw any assumptions from the above, then the time lapse from prime ignition till the bullet has left the barrel, is less than 3/30th, or 1/10th of a second. In other words, the total time; from tripping the sear to the bullet exiting the barrel, is less than 6/30th or 1/5th of a second.
Listening to the audio recording, two distinctive sounds; one following immediately on the other, is heard. But, there is no delay between these sounds, rather the louder sound flowing from the softer (priming) sound.
Please understand; these are observations made within my ability and with the (accidental) recording facilities I had available. In addition, we shot the BBJB without the new priming mix and the delay in ignition is, apart from an embarrassing ”˜flash in the pan’ observably slower.
Comparing these video clips to parts of two commercially produced videos (Homer Dangler’s gun building video and The Long Hunter Series) where flint guns are fired; again shows, by observation, no observable difference in a flint gun using black powder and that I obtained yesterday using the mixed prime and substitute powder.
No doubt, a lot of experimentation still lies ahead. One can play with the ratio used in the priming mix and even with the location of the prime viz a vie the vent. Also, what remains to be determined, is whether the same results can be obtained in guns not using coned vent liners and/or with vents placed ahead of the breech face (commercial guns).
But I am satisfied that I achieved what I set out to do: making (my) flint guns shoot satisfactorily with substitute black powder while using a minimum of black powder as a boosting charge.
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If it ain't a ball, it ain't a bullet
