Bart B.
Would you rather I use xylophone bars, or tuning forks?
A barrel is much like a tuning fork, except you shave off the bottom fork and replace it with a stock forend.
If you want to increase the pitch of a vibrating rod, put a dampening point at the halfway position, what this will do is give you a perfect octave. 1/2 the length, 2x the fundamental pitch. 1/3 the length (two evenly spaced pressure points) 3x the pitch, so forth and so on.
As you know, stiffer barrels resonate at higher frequencies. By putting pressure at some point, you are intentionally creating a harmonic at some multiple of the fundamental.
Barrel blocks work in a similar manner, they totally encase the barrel to some distance forward the action, and so you can free float the rest of the barrel which will resonate at a higher fundamental frequency (be stiffer) and also free float the action. The difference with a pressure bed is that it maintains contact with the stock at the action and at the forend. Of course barrel blocks also take the majority of tension off the action threads, which is very important with very heavy barrels.
As a service rifle shooter, you have probably seen rack grade rifles that shot very tight with the sling used, but you put those rifles in a rest and the groups open up. The sling is acting as a damper on the barrel, which is "tuning" the barrel forward of the sling position to a higher frequency.
Conservation of energy tells us that the amplitude of the higher frequency will decrease (more deflections back and forth in the same time means less distance between peaks and troughs compared to fewer oscillations in the same time which means more distance between peaks and troughs).
But if I wasn't clear before, pressure bedding is not an optimal way to get accuracy from a rifle. If free floating doesn't work, pressure bedding is the what you try before going to a rebarrel. Once you put the stock back into contact with the barrel, it is tough to maintain consistent pressure at that point which produces consistent harmonics, which is why it is a technique pretty much reserved for hunting rifles that aren't expected to shoot long strings.
Jimro
Would you rather I use xylophone bars, or tuning forks?
A barrel is much like a tuning fork, except you shave off the bottom fork and replace it with a stock forend.
If you want to increase the pitch of a vibrating rod, put a dampening point at the halfway position, what this will do is give you a perfect octave. 1/2 the length, 2x the fundamental pitch. 1/3 the length (two evenly spaced pressure points) 3x the pitch, so forth and so on.
As you know, stiffer barrels resonate at higher frequencies. By putting pressure at some point, you are intentionally creating a harmonic at some multiple of the fundamental.
Barrel blocks work in a similar manner, they totally encase the barrel to some distance forward the action, and so you can free float the rest of the barrel which will resonate at a higher fundamental frequency (be stiffer) and also free float the action. The difference with a pressure bed is that it maintains contact with the stock at the action and at the forend. Of course barrel blocks also take the majority of tension off the action threads, which is very important with very heavy barrels.
As a service rifle shooter, you have probably seen rack grade rifles that shot very tight with the sling used, but you put those rifles in a rest and the groups open up. The sling is acting as a damper on the barrel, which is "tuning" the barrel forward of the sling position to a higher frequency.
Conservation of energy tells us that the amplitude of the higher frequency will decrease (more deflections back and forth in the same time means less distance between peaks and troughs compared to fewer oscillations in the same time which means more distance between peaks and troughs).
But if I wasn't clear before, pressure bedding is not an optimal way to get accuracy from a rifle. If free floating doesn't work, pressure bedding is the what you try before going to a rebarrel. Once you put the stock back into contact with the barrel, it is tough to maintain consistent pressure at that point which produces consistent harmonics, which is why it is a technique pretty much reserved for hunting rifles that aren't expected to shoot long strings.
Jimro