From: bartb@hpfcla.fc.hp.com (Bart Bobbitt)
Subject: Re: Hot .308Win Load?
Organization: Hewlett-Packard Fort Collins Site

James Foster x2912 (James.A.Foster@cdc.com) wrote:

: So how much stringing are we talking about here?   Something that the
: benchresters and varminters should worry about, but not that important
: for the deer and the antelope players?  This gun will be used for full
: power hunting loads with 150 grn or heavier bullets (brands and styles
: TBD).  Do you see fractional MOA stringing, or is it worse, or is it just
: too hard to predict for a given gun?

I think groups with highpower rifles will string about one MOA more in
the vertical axis and about one-third MOA more in the horizontal axis when
the barrel's back end has a bedding pad under it.  This is for 30 caliber
rifles.  Smaller caliber ones may be different.  I don't know about the
stool-shooter's (benchresters) rifles; they may or may not do best with
a bedding pad, but I doubt it.

Many years ago, I took three bolt action match rifles and rebedded their
barreled actions with 2 inches of pad under the barrel in front of the
recievers.  They were fitted with a scope and tested at 600 yards with
20-shot groups.  Two were .308 Win., one was a .30-.338 magnum.  Each
one started out shooting groups at 600 yards that were about 9 inches
tall and 5 inches wide.  I removed a half-inch of bedding and retested;
groups reduced to about 7 inches tall by 4.5 inches wide.  The groups
reduced in size more after another half-inch of the bedding pad was
removed.  When the pad was completely removed, that is with the barrels
completely free-floating, the groups were the smallest; about 4 inches
for the .308s and 3.5 inches for the .30-.338.

I repeated this test with three sporting rifles; one Win. M70 in .308 Win.,
a Rem. M700 in .243 Win. and a sporterized Springfield M1903A3 in .30-06.
Each was fired at 200 yards; again, 20-shot test groups.  The groups
And each had about 1.5-in. of bedding under the barrel in front of the
reciever.  Each shot groups about 4 inches tall and 3 inches wide to begin
with.  After removing a half-inch of bedding and repeating the test, each
had smaller groups in both height and width.  Sure enough, after the epoxy
was completely removed beneath the barrel, the groups were the smallest.

I epoxy bed my reciever's full-contact, except for the bottom of the
recoil lug(s) which have about .025-in. clearance.  And the entire reciever
is bedded at the same time; not one end first, then the other as is often
suggested in printed material about epoxy bedding.  I use Devcon Plastic
Steel and my release agent is Simonize car wax.  Front and back stock
screws on my Win. M70s are torqued to 60 inch/pounds; the middle one is
just snug at about 40 or so inch/pounds.

Several years ago, one of our local highpower shooters used a machine rest
to test both rifle and ammunition.  His rifle had a bedding pad for about
2 inches at the back of the barrel.  In testing at 600 yards, his groups
were about 8 inches.  He removed about an inch of the bedding; groups went
to 6 inches.  After removing all of the bedding pad and completely free-
floating the barrel, test groups shrank to about 4 inches.  He had been
a true believer in bedding pads but quickly changed his mind.

In talking with Lones Wigger (USA and International smallbore champ), he
says that most smallbore match rifles have a bedding pad under the barrel.
Some mouse-gunners had tried a completely free-floating barrel, but those
with an inch or so of epoxy at the back of the barrel seemed to shoot a
tad better.  Perhaps this technique works positively for .22 LR match
rifles.  I've not tested any nor do I have any test data favoring either
technique.

Once in a while, I'll a highpower  match rifle that has a pad under the
barrel at its back end.  And these rifles will shoot real good for some
reason.  Perhaps they were bedded differently than how I do it; like in
the reciever area or something.  But there's one big disadvantage of
having bedding under the barrel; when a new barrel is put in, the bedding
must be removed first, then rebedded if that's the owner's choice.  It
is an added process for rebarreling.

So, I'm not in favor of any bedding touching the barrel.  I've not seen
any advantage of it.  Some folks claim it's needed to take some of the
stress off of the reciever/barrel at that point.  I don't buy this line
of reasoning; the force on the reciever's barrel thread section caused
by the barrel's weight is still there, although it may be distributed
somewhat differently.

Each of us gets to decide how accurate we want our rifles to be.  Then
make 'em shoot that accurately.

BB

From: Gale McMillan <gale@mcmfamily.com>
Newsgroups: rec.guns
Subject: Re: Repost: Free floating barrels
Date: 25 Oct 1997 21:53:25 -0400

EWS14464 wrote:

# What are opinions of free floating sporting rifle barrels?  Synthetic
# and wood?
#
# Thanks
#
# EWS

Good barrels will shoot better free floated and poor barrels need forend
pressure.  The reason being that when you put forend pressure on a
barrel you bend it in a small ark and as the bullet goes down the barrel
it trys to straighten out the ark and it forces the barrel down so that
the bullet exits the barrel while it is in the same position each shot.
A good barrel that is stress relieved and has he hole in the center will
generally shoot better free floated.  I recommend trying any first free
floated and then with a little pressure and use the one who works best.
It is easy to bed the tip with a little pressure if needed.