Are fully-floated barrels universal in centerfire benchrest?

S

South_Pender

New member
I hope this isn't too basic a question, but I'm wondering whether everyone uses fully-floated barrels in benchrest or whether some use some up pressure on the barrel--maybe at the forend tip.
 
It is interesting to see how much a thick stainless steel barrel (or any kind of steel) vibrates / oscillates.

When I was in engineering school I had a physics professor that set up an interesting demonstration one class. On a heavy work bench was a huge and heavy vise. Consider it the action, bedded and glued in place. Clamped in the vise was a long, about 3 foot, solid stainless steel rod about 3 inches in diameter. It was in free space from the vise outward. At the end of the rod, suspended from an over head hanger, was a white cue ball, that had been drilled allowing for an eye hook to be set in it. A string connected the ball to the overhead hanger allowing the ball to be suspended just touching and center on the end of the rod.

The profession (Freddie First for anyone who went to Steven's Institute of Technology in the 60s, then took a chamie, wrapped it around the rod and started stroking it back and forth. All of a sudden you could see that the cue ball was vibrating and once he was able to get the rod to hit resinence, the cue ball shattered into dust.

He actually mentioned that a projective traveling down a rifle barrel sets up similar oscillations, albeit for a faction of the time.
 
So, no one using a forend bedding device--like the one you used to see in Rem. 40X rimfires? You could vary the tension via a screw in the forend. The theory was that some contact at the forend tip helped to damp the barrel vibrations.
 
rkittine said:
It is interesting to see how much a thick stainless steel barrel (or any kind of steel) vibrates / oscillates.

When I was in engineering school I had a physics professor that set up an interesting demonstration one class. On a heavy work bench was a huge and heavy vise. Consider it the action, bedded and glued in place. Clamped in the vise was a long, about 3 foot, solid stainless steel rod about 3 inches in diameter. It was in free space from the vise outward. At the end of the rod, suspended from an over head hanger, was a white cue ball, that had been drilled allowing for an eye hook to be set in it. A string connected the ball to the overhead hanger allowing the ball to be suspended just touching and center on the end of the rod.

The profession (Freddie First for anyone who went to Steven's Institute of Technology in the 60s, then took a chamie, wrapped it around the rod and started stroking it back and forth. All of a sudden you could see that the cue ball was vibrating and once he was able to get the rod to hit resinence, the cue ball shattered into dust.

He actually mentioned that a projective traveling down a rifle barrel sets up similar oscillations, albeit for a faction of the time.
Click to expand...

that is sooo friggin kewl.

My kids are big fans of Walter Lewin, Khan Academy, Destin Sandlin (SED) et al........ As much as the innernet gets bashed, it's STILL the coolest teaching instrument in the history of the world.
 
If

alinwa said:
that is sooo friggin kewl.

My kids are big fans of Walter Lewin, Khan Academy, Destin Sandlin (SED) et al........ As much as the innernet gets bashed, it's STILL the coolest teaching instrument in the history of the world.
Click to expand...

the information or news is true.
 
rkittine said:
It is interesting to see how much a thick stainless steel barrel (or any kind of steel) vibrates / oscillates.

When I was in engineering school I had a physics professor that set up an interesting demonstration one class. On a heavy work bench was a huge and heavy vise. Consider it the action, bedded and glued in place. Clamped in the vise was a long, about 3 foot, solid stainless steel rod about 3 inches in diameter. It was in free space from the vise outward. At the end of the rod, suspended from an over head hanger, was a white cue ball, that had been drilled allowing for an eye hook to be set in it. A string connected the ball to the overhead hanger allowing the ball to be suspended just touching and center on the end of the rod.

The profession (Freddie First for anyone who went to Steven's Institute of Technology in the 60s, then took a chamie, wrapped it around the rod and started stroking it back and forth. All of a sudden you could see that the cue ball was vibrating and once he was able to get the rod to hit resinence, the cue ball shattered into dust.

He actually mentioned that a projective traveling down a rifle barrel sets up similar oscillations, albeit for a faction of the time.
Click to expand...

Good post...and very interesting.

Mort
 
In rimfire where the load can't be changed to tune for more accuracy the forend pressure point was/is used in an attempt to modify the barrel vibration to a condition that would give greater accuracy.

Many hunting rifles especially where a fixed (factory) load is used the forend pressure point can sometimes give greater accuracy.

I seriously doubt if a forend pressure point has been successfully used to improve accuracy in centerfire benchrest rifles.




.
 
I ain't sayin' that it won't make the rifle shoot better but rather few, if any, use any method other than free all the way. Your rifle, or maybe my rifle, might shoot better with the forend pressure you mention.
 
Just don't use wood in the fore-end if it's touching the barrel as every variation in humidity and temperature shall result in a change in the POI as the wood grows and shrinks in sympathy with the climate.

If you insist on wood, seal it as best as you can and leave a fair gap between the wood and the barrel ahead of the action ;-)

* doggie *
 
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