Barrel resonance

[Franco2shoot]

Ok now I'm thoroughly confused...

First, I thought a barrel that was floating, ie. not supported, was a good thing in terms of accuracy... Then I read where it's better to have a good bedding indicating the barrel should be equally supported fore and aft.

Now I have a 60+ year old Mosin Nagant 91/30 with that elegant long barrel which by the way I can wiggle out by the muzzle, maybe a 32nd of an inch -up/down/left/right. It holds fairly tight groups at 100 yards, but as everyone knows tighter is better. Incidentally, it holds pretty much the same pattern with the bayonet attached, just up and to the left by almost 5 inches.

So I need an explanation. Did the Soviets know their stuff and invent floating barrels? Should I go a-looking for some cork to put under the barrel up front and maybe a shim or two over the top to tighten up everything and dampen the the vibrations? Maybe its better to let it "ring" with each shot... Every gun play's it's own tune ( I think that's a line from the Good, the Bad, the Ugly)

What's the real story as far as accuracy? I can prolly(southern term) find out for myself at the range, but it will take 100 or so shots to determine and I'll bet the resident knowledge out on this board knows the answer.

KKKKFL

 

[nicholst55]

There's an article on The Box O' Truth where they put cork shims under the muzzle end of their barrels and it significantly reduced their group size. Try it, you might like it. Or not.

 

[Vern Humphrey]

Stocks influence accuracy when they exert pressure on the barrel. If the pressure is uneven, it can hurt accuracy. In addition, as the barrel heats up, it expands, which changes the stock pressure. On the other hand, stock pressure can damp out vibration, which also affects accuracy.

In general, a free-floated barrel avoids stock pressure problems. With very long, or skinny barrels, however, a V-block arrangement in the forearm will sometimes aid accuracy -- that's why a pair of shims (at the 4:30 and 7:30 positions) will sometimes help accuracy.

 

[Franco2shoot]

Thanks Vern... It is just so easy to pop the retainers off and put a shim in I'm gonna test it out and will report back.. As I indicated, I can wiggle the barrel now, but I can easily whack a piece of balsa into a paper thin wedge. Test report coming soon.
KKKKFL

 

[Vern Humphrey]

Try using an ordinary business card.

 

[bogie]

Sometimes it helps, sometimes it hurts.

It tends to be fairly inconsistent. People have tried using adjustable "shims," and the barrels were more apt to have problems with changes in weather.

Group size has two components. Vertical (barrel resonance, shooter control/trigger/bench technique, and to a lesser degree wind) and horizontal (wind, shooter/trigger control).

I'm guessing 99% of benchrest barrels are free floating.

One VERY interesting rifle belongs to a guy I know who sunk the whole barrel in epoxy... About 3" thick, on an unlimited rifle. That barrel is DEAD. Very little vertical resonance, very easy to tune, very accurate.

 

[icebones]

maybe your bending the wood, not the barrel, or perhaps i misunderstood you, if that rifle (considering its age) shoots goot tight groups, leave it alone
as a wise man once said: if it aint broke, dont fix it

if anything, the barreled action is moving around in the stock, if you really want to, glass bed just the action to the stock, it will help stiffen up the entire weapon, i have an old (1897 manufacture) mosin too, but it has a full length wooden stock, the handgaurd leaves just about 5'' of the barrel sticking out. and for its age it shoots good, scary good. we are talking about the same people that gave the world the AK-47 and vodka ,
i think those russians know what their doing...

if anything, you want consistent, even pressure.