Harmonics Parrelal VS tapered barrels

R

rooshooter

New member
Does anyone here have any views on barrel harmonics on tapered barrels VS straight barrel. As in, with 2x barrels of the same weight and length (say 30") in 1000yd BR light sizes, will a straight 1.2" no taper barrel vibrate the same as a barrel which is 1.35 at the chamber, going down to 1" at the muzzle. I wasnt after coments like, my dads deer rifle has a tapered barrel and it shoots good.
Will the straight one vibrate more, but be easier to tune, while the tapered one vibrates less, but faster if you get my meaning?
 
rooshooter sir

it is more about length than taper to get a wide tune. tim in tx
 
rooshooter,

Sorry if I seemed abrupt. I'd hoped to get some responses from folks taking the time to elaborate.

In the case you've described I'm still at a loss as to how to interpret your meaning though. The term "vibrate more" is imprecise to me.

Vibration is generally described using two distinct measurements, amplitude and frequency. Generally speaking amplitude is the height of the waves and frequency is the distance from crest to crest. "More" or "less" doesn't really make any sense to me.

Also generally speaking, barrels which exhibit lower amplitude are considered to be "stiffer" and they vibrate at a higher frequency. Some people (I'll include myself) feel that a barrel which is too stiff is actually harder to keep in tune due to the shorter distance between nodes...... even though they show smaller dispersion on target from crest to trough of their "waves," their tuning windows are smaller. So even though a stiff barrel may shoot groups with little vertical they also cannot be easily tuned to shoot dots and kept there.

Regarding which of your barrels will act "more stiff" I'm at a loss..... upon rethinking your post I'm inclined to believe that my knee-jerk response was WRONG, that in your example the straight barrel may actually be "looser" or show more dispersion (greater amplitude) due to it having more weight forward.

I'm out of my depth here, it would take a Varmint Al type to actually show the analysis of your two interesting examples.

any takers?

al
 
Al, by vibrating more, I meant amplitude. I was thinking that a straight barrel with more weight up front would have more amplitude, but a slower frequency, and that a realy stiff (Wide at the chamber) barrel, would have a lower amplitude, but faster frequency, so as you say, it would have a narrow tuning window. I wasnt sure how it would be affected by being stiff and heavy at the chamber end, but lighter and less ridgid at the muzzle.


Tim, I was trying to keep the barrel at about 29" long and work within a certain weight limit.
 
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Another question I had was, if using a barrel bedding block, where does the tuned length start? As in, with a 30" long barrel, its node is usualy around, say 2820 or 2950 fps, but lower speeds with a shorter barrel. If there is only 23" of barrel hanging out of the bedding block, would the nodes be the same?

All theoretical questions of course, which actual testing would be the answer, but just something I have been pondering that I thought someone with thick glasses and lots of pens in their top pockets might be able to answer.
 
geek shooters...

Hi Down-under-oooo shooter....most guys with thik eye glasses and lots of pencils and smooth worn keypads on their puter dont know squat abut shootin....you will get lots of smoke blown ur way...but the best answer is use as much bbl as your gun can have and make wt...or as you can carry comfotably.....then blow you own smoke outa the muzzle...maby you can let us know....these guys that have to start at scratch evry time they install a new bbl or even adjust the scope culdnt find the "tune" on a car radio...let alone a target rifle.....use proven powder/bullet/etc....if it anint shootin within 50 rds....it never will....Roger
 
Bill Shehane,D&B supply

give Bill a call or e-mail, his recommendations worked very well for my Blocked rifles. Escentialy you shorten the (Harmonic length) by the length of the barrel block,eg..30"bbl -6" block =24" available for harmonic oscilations.
 
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