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20 vs. 12 gauge for hunting

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Rich

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Round ball from a 12 ga has a very arcing trajectory, I would go with 20 bore. Mine has taken deer, mule deer, and elk with no trouble
 

Rudyard

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Rather even think about chokes in any muzzle loader Ide suggest you buy a nitro breech loading affair because your evidently after modern performance . Shotguns intended for game birds ect had relief bored barrels not cylinders but open behind & forcing the charge into a tighter space ere it reaches the muzzle when apon it opens up , the very reverse of choke . The likes of Lt Col Peter Hawker shot more game than you could poke a stick at without chokes . He had the time & the wealth too indulge his passion. If you care to read his ' Instructions to young Sportsmen' & all that relates to guns & shooting' printed in many editions even an American one it would be entertaining. But there are no choke notions as I recall . A veteran of the Peninsular war he shot through the high noon of flintlock & into the era of percussion.

As Hanshi puts it' Young guys should listen to old guys they know stuff ' or words to that effect .
Rudyard
 

rodwha

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If you shoot 1 ounce of shot from a 12 gauge, I doubt you are going to see much, if any difference shooting 1 ounce of shot from a 20 gauge. If you instead shoot 1 1/2 ounces of shot from a 12 gauge, then you will have the potential for more hits on the animal. You had mentioned shot sizes, and there is a whole can of worms there. Some choose very small sizes, and go for a headshot. I don't like this thinking, and I find it results in shot left in the meat. When talking about ducks or geese, I like to choose a shot size that will go all the way through the breast, and all the way through the organs at the maximum distance that my pattern will be effective.

@rodwha, if you use chokes, I would think you could get an acceptable pattern with #6 shot at 25-30 yards without too much trouble. I don't like screw in choke tubes, not even in modern guns. In a muzzleloader, you will have to unscrew it for every single shot. You might be able to get away with a more open choke like IC or modified, but a full, or extra full you certainly wont.
I really would prefer jug choking but I can’t find anyone who does small gauges. Unscrewing a choke to install a cylinder choke for loading and then switching back sounds ridiculous, but outside of testing loads there shouldn’t be too much of that. I actually was considering having a 15/16” turned into a 24ga, about as large as it can go, but figured for turkey I’d likely need a choke so 28ga it is, not to mention trying out patched .530” balls.
 
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You don't have to put in a cylinder choke, you only have to remove your tight choke for loading. Reason being, you can't start wads through a tight choke, at least not without mangling them. It sounds like a good reason to get the 20 gauge to me.
 

The Crisco Kid

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This is and interesting thread since I have in mind building a 20 gauge "canoe gun" using an old barrel from a single shot. With the chamber cut off there is still plenty of metal left to be safe. I'll have to ream out the choke of course. Last night I filled a 45-70 case with Goes FF. it weighed 75 grains. Filled with some #2 shot I had the charge weighed just a little over 1 oz. Looking in my Dixie Gun Works catalog this duplicated their heavy charge for a 20 gauge.
 

Britsmoothy

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I had no problems getting my wadding past a choked muzzleloader!
Then again I listened to the old guys on how to do it.
 

Onojutta

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Round ball from a 12 ga has a very arcing trajectory, I would go with 20 bore. Mine has taken deer, mule deer, and elk with no trouble
I forget where I read that the most ballistically efficient round ball size is somewhere around .45 cal. As the diameter gets bigger from there, the aerodynamics worsen and I don't believe it is a linear relationship. This stands to reason in terms of "vortex shedding" or the turbulence created as airflow moves around a round object. Anyway, in the context of shotgunning, my question as the OP had more to do with shooting shot than roundball, since I have rifled guns for that task.
 
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I had no problems getting my wadding past a choked muzzleloader!
Then again I listened to the old guys on how to do it.
You certainly can get wads past some choke. I like to turn them sideways and push them in, then turn them right with the ramrod. rodwha mentioned longer shots at turkey, which would mean a tighter choke, .030" maybe .040", and it is a real job to get a wad past a choke like that without ruining it. If I were to try, I would use thin overshot cards for over the powder, and just use maybe 8 of them.
 
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I forget where I read that the most ballistically efficient round ball size is somewhere around .45 cal. As the diameter gets bigger from there, the aerodynamics worsen and I don't believe it is a linear relationship. This stands to reason in terms of "vortex shedding" or the turbulence created as airflow moves around a round object. Anyway, in the context of shotgunning, my question as the OP had more to do with shooting shot than roundball, since I have rifled guns for that task.
This simply is not true. I'm not exactly sure if it is linerar, but the BC of round balls is very simple. The bigger the ball, the better the BC. A .715" ball has a higher BC than a .440". The only reason a 45 caliber will shoot flatter is that you can shoot them faster without insane recoil. I don't think 1800-2000 fps is unusual in a 45 caliber, while I doubt a 12 gauge or 75 caliber is shot much faster than 1200-1300 fps or so very often, as the recoil gets very heavy.
 

Zonie

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You are correct in saying the Ballistic Coefficient of the larger .54 diameter ball is better than that of the .45 diameter ball.

The ballistic coefficient is dependent on the mass of the projectile and the area of its diameter.

While the area of a given sphere is given by the formula, pi times the radius squared, the mass (volume) is the product of 4 times pi times the radius cubed divided by 3. The important thing here is, because the radius of the ball is multiplied times itself 3 times in the case of the sphere, the mass (weight) gets much larger, much quicker, than the area of the hole the ball cuts thru the air as it flies downrange.

That ends up making the larger ball maintain its velocity better than the smaller ball does.
 

Onojutta

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Sorry guys, I don't remember where I came across that info but I disagree with both of you. It's not as simple as the greater the mass or velocity, the better. The drag and aerodynamic pressures that negatively affect accuracy are influenced by the geometric shape and velocity, and generally increase exponentially. It was years ago when I looked into this and don't have any supporting info handy so I'm not going to argue it here. But I'll do some digging and post if I find it.
 
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It isn't a matter of agreeing or disagreeing. It is physics, specifically ballistics. The following is the ballistic coefficients from the Lyman muzzleloading manual.

.310/45 grain = .043
.350/65 grain = .049
.440/128 grain = .062
.490/177 grain = .068
.495/182 grain = .070
.535/230 grain = .075
.570/276 grain = .080
.690/494 grain = .086
.715/545 grain = .097

Also note that ballistic coefficients are not constant. The faster you shoot them, the lower the BC. A 45 caliber has a very poor BC, especially at high velocities, but because of that velocity it still shoots quite flat for about 125 yards. It does still deflect greater in the wind though, even with that velocity. A 45 caliber at 2000 fps will drift about 13" at 100 yards with a 10mph crosswind. A 75 caliber on the other hand at 1200 fps will drift about 7", all other variables the same. I like to play with the following calculator a lot.

 

rodwha

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You don't have to put in a cylinder choke, you only have to remove your tight choke for loading. Reason being, you can't start wads through a tight choke, at least not without mangling them. It sounds like a good reason to get the 20 gauge to me.
I figured it a good idea to protect the threads, especially since it’s softer steel.

Ultimately I want my 15/16” rifle to be convertible with a few drop-in barrels. My Deerstalker is a .50 cal with the deeper grooves for a PRB and 1:48 to possibly use conicals for larger game. For small game and possibly turkey I’ve contemplated a .52 smoothbore so I can patch my .490” balls, the 28ga so I can potentially use chokes since its quite possible I won’t/can’t find a good enough pattern at 25 yds, but also it would allow me to try modern components if I wanted, and .530” balls, and finally the 24ga as it seems that’s the largest a 15/16” can be taken to. And so I sort of settled on a 28ga since it has options, shares ball size with something I may one day own.

The larger bore guns I’ve looked at and wanted are all quite pricey, especially when my other hobbies eat into the funding. Barrels can be fairly inexpensive. But I’ve just been a bit fascinated by the idea of building a small box for this rifle and a couple of extra barrels, something I can take in my truck and know I can hunt pretty much anything. And I like to put things SWMBO doesn’t care much for on my Christmas lists so I could well end up with an additional .54 cal for larger game, maybe an 18” 28ga to be loaded with buck n ball for the possibility of tracking wounded hogs, or maybe a .40-.45 cal fast twist long barrel topped with a Malcolm (also on that list 😆) for hunting fields and such. A lot of options in one package that aren’t too expensive necessarily. I’ve been looking into the same thing with the 13/16” Crockett with a .45-something for paper patching my custom revolver bullets over maybe 40-60 grns with a 22-26” barrel, as well as a common .410 just because of modern options, .45-something to use my revolver wads and punched cardboard over powder cards, or .488 to patch my .457” balls, though I’m not sure if that stretches a 13/16” too far. I figure 24-28” is good for a little shotgun like that.
 

Onojutta

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I just realized I used the wrong phrase in post #88 when I said "ballistically efficient". I meant efficient in terms of stability for accuracy, not ballistic coefficient. Sorry for the confusion.

BC has to do with overcoming the air resistance and you guys are right about that stuff. The behavior I was referring to has to do with the ball moving around while it's in flight. Think of one of those exhibits they have in a science museum where a ping-pong ball is suspended in a stream of air and it zig zags all over the place. A round ball, especially one that is not spinning, does the same thing in flight. A bigger round ball will have a greater BC, but the BC is not what directly affects this "flight path stability" in this regard.

Anyway, the material I keep mentioning demonstrated that somewhere in the low to mid 40-calibers was the tipping point and as caliber diameter increased from there, the accuracy suffered.
 
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You might have me there. I'm not a big time rifle shooter, but it sure seems like the 45ish caliber area is very common in competitions. I've never competed myself either though, so that's not even a full 2 cents from me.
 

Britsmoothy

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I just realized I used the wrong phrase in post #88 when I said "ballistically efficient". I meant efficient in terms of stability for accuracy, not ballistic coefficient. Sorry for the confusion.

BC has to do with overcoming the air resistance and you guys are right about that stuff. The behavior I was referring to has to do with the ball moving around while it's in flight. Think of one of those exhibits they have in a science museum where a ping-pong ball is suspended in a stream of air and it zig zags all over the place. A round ball, especially one that is not spinning, does the same thing in flight. A bigger round ball will have a greater BC, but the BC is not what directly affects this "flight path stability" in this regard.

Anyway, the material I keep mentioning demonstrated that somewhere in the low to mid 40-calibers was the tipping point and as caliber diameter increased from there, the accuracy suffered.
That probably explains why most smoothbores shoot better (ball) loaded to high velocity. The air buffering of the ping pong ball is relative to the air speed. Turn the air speed up and the ping pong ball would fly off on a true (ish) course.
 

Spence10

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Think of one of those exhibits they have in a science museum where a ping-pong ball is suspended in a stream of air and it zig zags all over the place. A round ball, especially one that is not spinning, does the same thing in flight.
An object moving along a line will continue on that line unless outside force is applied. I'd like to know what force will make a roundball zig and zag.

Spence
 

Rifleman1776

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An object moving along a line will continue on that line unless outside force is applied. I'd like to know what force will make a roundball zig and zag.

Spence
Spence, that principal applies only if the object (e.g. round ball) is a perfect shape. A deformed object will creat it's own 'outside force' and can wobble in flight.
 

Spence10

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Spence, that principal applies only if the object (e.g. round ball) is a perfect shape. A deformed object will creat it's own 'outside force' and can wobble in flight.
Zig and zag is not the same as wobble. It implies moving away from the line of flight, maybe more than once. Wobble can just be rotation on its axis without changing the direction of flight.

Spence
 
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