Free-floating Barrels & Tube Magazines

[Kipling79]

I never realized how much detail was involved in making a firearm accurate. Until recently I had no idea what a free floating barrel was.

My search brought up nothing, so here is my question:

1) Does the tube magazine attached to a .22 rifle decrease accuracy? (mine is attached by a screw to the reciever and a sleeve support midway down the barrel, like your standard .22 tube magazine)

2) If so, is there any way to increase the "free floatingness" of this barrel while keeping the magazine? (Maybe engineer a way to "float" the magazine?)

 

[Slugless]

I wouldn't bother trying to float the magazine away from the barrel. The idea of floating is to keep the barrel from slapping/rubbing/binding against the stock as it's "ringing". If you attach a mag tube, the barrel/mag tube will "ring" at the natural frequency of the combination. You can still float the combination of the two away from the stock so the stock doesn't interfere.

On the Marlin forum at www.rimfirecentral.com there's discussion on free floating Marlin 60s. Not everyone benefits, apparently. (Unrelated to floating I've also heard the tension on the front action screw makes a difference). You can try a poor man's free float on a 60 by shimming the action up away from the barrel.

I've been working on some 60s lately & will get around to the shim float just to see.

I'd also check the fit between the mag tube and it's holder. If there's play between the two the mag tube can flop around and produce a less consistent "ring." You could shim the mag tube with paper shims to see if it made a difference.

 

[30Cal]

Generally, on rifles where there's stuff hanging off the barrel, good results can be had by applying a constant pressure in the barrel. This will help dampen out then bad vibes caused by the extra junk.

Ty

 

[Outlaws]

The idea of floating is to keep the barrel from slapping/rubbing/binding against the stock as it's "ringing".

No. The idea of floating is to keep you from applying uneven pressure to the barrel on each shot. Bedding the action about an inch further under the barrel is to limit the ringing sound.

 

[Slugless]

"Uneven pressure" is what I was referring to. One of the many things I do at work is vibrational analysis on piping and on combustion systems. A tube-fed rimfire with a cantilevered skinny barrel that heats & cools, a wood stock that swells and shrinks with ambient temperature & humidity, a cylindrical mass loosely slung underneath whose mass changes with every shot, poor bedding + the various pressures the shooter puts on the stock with slings, bench position vs standing, etc. - it's a very complex system.

I tend to use simple, more visceral terms when describing complex phenomena to an audience not experienced in the field. I find it more effective to use "slide" rather than "forces tangential to the mating surfaces." While not technically correct, saying:

"The barrel of a cheap tube-fed rimfire shimmies like a one-legged go-go dancer"

is more memorable than droning on about the vector addition of barrel/tube/stock harmonics as a function of time. Other technical types sometimes roll their eyes.

I admit that normally I hire PhD's to do complex modal analysis, I stick to the simpler structural and acoustic calculations. I have, however, observed evidence of stock/barrel movement causing uneven pressure and wear on the bluing of the rimfire barrel shown below. The rifle shot more consistently when I relieved the pressure points.

A well built centerfire rifle is simpler. I've never seen evidence of stock/barrel movement on a centerfire.