Question on stock geometry

[The other DWS]

sounds like we are mixing up a whole lot of stuff in this most interesting stew.   I'd suggest looking at the purpose of a given rifle when it comes to geometry.

 an early military musket or rifle had to be built to a standard--for military needs and training methods and in the flintlock era sturdiness for bayonet work and general military abuse as well as cost were more important than individual fit for accuracy.  in addition they were all trained to shoot in a given stance---plenty of illustrated manuals exist to illustrate that point.  I well and painfully remember my first experience with live rounds out of a Charleville repro, short stock + "modern offhand stance"= massively bloody nose from the thumb wrapped over the wrist

fowling guns and guns designed to be used with shot loads are designed to be shot instinctively (a much abused term) are usually designed for quick shouldering and a comfortable way to handle recoil since typically they'll be used for more shots in a given hunt than a rifle.  they might be given a bit more attention to individual fit,

eastern rifles in the earlier years that were used by the, say, pre-1820 pioneers were more likely to be sturdy and designed for woods work hunting and warfare, probably quick and handy and a lot more like the fowling pieces than the rifles of the following era.  Shooting probably was more stealthy and shooting from a formal offhand position was probably relatively rare other than an occasional match or two or a quick snap shot at game or perhaps a moving enemy.

post 1820  the need/purpose changed, more settlement, less large game, smaller and longer bores, transition to percussion(?) more casual and recreational use.  recoil management was less of an issue and the more stylized dropped crescent butt and a more formal offhand pose, (perhaps affected by the expanding popularity of the "schuetzen type" target shooting popularized by the rapidly expanding 2nd wave of German Swiss immigrants)  the crescent butt made a good compromise between the schuetzen hook butt which was almost totally unusable in the field and the previously used flatter plate needed to handle heavy recoil.

just speculation on my part from a cultural history standpoint.

[Dr. Tim-Boone]

Phew,  maybe it was just a fashion trend like skirt lengths

[Artificer]

I've been trying to remember the term they used in the 70's for the deep crescent BP rifles and long heavy barrels and even though I suffer from "Half Zheimer's Disease,"  I think I finally remembered it.  They used to call them "over the stump" rifles, if I remember correctly. That meant they were intended to be shot from a stump, a large fallen log or a table and not from the offhand.

 No matter what type of BP and hold one used on the butt of the rifle, the barrels were just too long and too heavy to have been meant to be used for regular Off Hand shooting and especially not for average hunting.  (Except in cases like a very good friend of mine who lives outside Louisville, KY and can have a cup of coffee on his back porch and could shoot deer without leaving the porch, though he doesn't actually do that.)

Besides hunting, we also have to remember in the 18th century that rifles were survival tools.  They didn't eat to hunt, they hunted to eat.  We also sometimes forget they were called upon to shoot other hostile people.  For those conditions, you want a rifle that can be fired rather quickly from even awkward positons and certainly from kneeling, sitting, and flat on your belly - fairly fast.  Those deep drop stocks with deep crescent BP's are not nearly as good as fairly flat or only slightly rounded BP's for that. 

I hope no one thinks I "have it in for" the deep drop, deep crescent BP rifles.  Even though I don't like to shoot them and doubt I will ever own one, I can still appreciate the craftsmanship and the history of those rifles. 

[ronward]

 i guess i don't understand the suggestions that i'm mixing BP/cartridge or modern powder facts with black powder characteristics.........
    if you burn X amount of BP in a .5 bore and then burn that same amount in a .4 bore, pressures will rise. it wasn't uncommon to put 70-80 gr. in a .4 gun and that amount was also a common load in the bigger guns. BP has a burn rate, just like smokeless does.....of couse a different rate, but a rate just the same and if you constrict the expansion of it's combustion with a smaller cumbustion chamber, just as in smokeless, it makes a higher pressure, constrict it enough and it finds other ways to make room for it's expansion......if it didn't, it wouldn't send the ball down the barrel. and esentially, it makes little difference whether there's a brass case containing the combustion or not, the area behind the ball is the same as the area inside a case.....the combustion chamber....and the consequenses of the combustion have the same effect on both, whether there's a case there or not.....  the case is more  a device of convenience than anything else....... the greatest difference is simply the level of pressures modern powders operate at vrs. BP.  in either scenario, if the combustion chamber,.... the barrel in the case of a ML gun...., or....the barrel and brass case in the case of a cartidge gun....., isn't strong enough to contain the combustion the barrel will fail regurdless of which powder genre.  by the time smokeless powders arrived, knowledge of internal ballistics and metalergy had advanced to the point that it was possible to predict the stregth of the combustion chamber needed to contain the cumbustion. as a result barrels got lighter because the need to over build a barrel from a lack of truely knowing how strong the barrel was eliminated. i truely don't think the barrels were made as heavy and long because the guns were "designed" to be shot off a rest......the bulders were making sure thier gun didn't injure people because they really didn't have any way to accurately measure it's strength or any way to predict the pressures involved, other than making a change when something happened. all the while working towrads lighter guns with interuptions in developement when they went a bit too far. i believe the builders operated in this mannor untill the advent of commercially available components that could be relied on as being safe because bigger, industrial money could afford the reasearch necessary to produce better componentry. the independant builders were certainly innovative and talented, but i'm also quite sure that they didn't have the rescorces to scientificly predict the results of thier ideas. they simply reacted with common sence to the conseqences of a failure when they took an idea too far.
    i sometimes think that we, at present times,with all our taken for granted convenience of math, shared knowledge and "big industry" , assumably inject a little too much of that into the  earlier methods of how these guns developed. surely, the math exhisted and was used to some extent by the bigger builders, maybe in europe, but the smaller independant guys,(don't forget that away from the big eastern cities, most of these guys were farmers and cabinet makers and such, not mathametitians and engineers) in the "new world" had no way to access that in a timely manner, so they plotted along relying on thier skills and common sence untill news of new developements finally reached them. then, providing thier shop had the capabilities, applied that new devolopement to thier guns.
   
   artificer,
      i'm not stuck on those plates either, i just happen to like the half stocked longer barreled guns, and want to build one of those as my first build. i might build it, shoot it and find out i hate those stocks, but that's the way they were built then, so that's the way i'm gonna built it now .
     my next one might be lancaster or some other flinter... i don't even know right now.....what ever the case, this thread has been about the most enjoyable i've participated in, in a very long time.   

[Artificer]

Ronward,

OK, now I think I have a better understanding of what you are talking about. 

BP cartridge guns have higher pressures due to the fact there is no "pressure release" point as in the touchhole on a flinter or even a nipple on a percussion gun.  Gas pressure escapes through the touch hole in a flinter and if everything else is equal, a flinter will have less gas pressure since the gas can more easily escape through the touch hole.  Too high of pressure in a percussion gun will cause the pressure coming from the hole in the nipple to throw the hammer back to and stop in half cock.  When loads are not that quite high of pressure, they can/will still cause the hammer to rise in a heavy load and then settle back down on the nipple from the foce of the mainspring acting on it- all before you would ever notice it becaue it happens so fast.   Also, in BP cartridge rifles, the bullet is larger than the bore and forcing that ball into the rifling causes higher pressures as well.

Gas pressure in a muzzleloader comes from the type of ignition system (as explained above) the quality of powder, the type of powder, the size of the powder grains, the amount of powder, the shape of the projectile, the size of the projectile, the weight of the projectile, the thickness and strength of the patching material, amount the powder is compacted, the size of the bore, and the twist of the rifling as a faster twist resists the ball going down the bore more than a slower twist and will have higher pressure from that alone, hot or cold temperatures also affect gas pressure from BP in loaded rifle barrels.  There are most likely other things I am not thinking about right off the top of my head as well.

We have to be careful when we talk about the types and quality of powders in the 18th century as gun powder was not as scientifically tested as it was even during the middle of the 19th century, let alone today.  We have no circa 1750 and circa 1830 cans of brand new black powder to test today.  However, it is generally accepted from empirical evidence that the quality of powder was much better circa 1830 than it had been in 1750, generally speaking.  Due to that alone, the same charge of the same size powder would give higher pressures in the circa 1830 powder than the circa 1750 powder.

When you talk about using the same charge of 70-80 grain charge of BP between a .4 and .5 bore round ball gun and I assume with similar patching material, rate of twist, etc., etc.  The pressure should be at least measurably greater in the .5 rifle than the .4 rifle.  This because there is more resistance going on in the .5 barrel with the heavier bullet. The size of the "expansion chamber" between the two bore sizes does come in as a factor, though, we are assuming both balls are seated correctly on the powder before firing and the difference is in the size of the bore the gas has to fill as the ball travels down the bore.  However, the resistance of a 177 grain .490 size pure lead round ball is much greater than an 89 grain .390 size pure lead round ball and without doing all the calculations, that should mean higher pressure in the .5 rifle even with the larger bore size.  The .5 ball is almost twice the weight of the .4 ball and that is a significant amount or resistance difference. 

What many people don't understand is that much of the force of the gas pressure is used up after the powder is burned and getting the ball to start from a velocity of zero up to it's main speed.  As the ball goes down the bore, it does slightly increase in speed even though there is not as much gas pressure as there was back at the breech.  In other words once you get the ball moving, it doesn't take as much force to slightly increase the speed of the bullet as it did to get the bullet moving.  This is true in both BP and cartridge guns, even though there has been far more testing with cartridge guns in this area.

Now, there will be a higher VELOCITY in the .4 rifle ball with the same powder charge because you don't have as great of resistance with the smaller .4 ball because it weighs so much less. Even with less gas pressure, you are slinging a much smaller ball with about the same amount of force when you use the same powder charges.   

Gas pressure and velocity are not the same thing and I think you are mixing the two together?

Gus