Wanted to hear you all's thoughts on this topic.

Why would a rifle be much more accurate when shot offhand or rested on cross sticks than when shot off of a bench, using either a sled type rest or sandbags?

The scenario is this:  I have a .45-90 rolling block.  I have shot this rifle a lot, enough to know it's accuracy.  Probably approaching 6,000 rounds.  It is accurate, with several different loads, to about 3 moa out to 1000 yards when used with cross sticks.  In fact, it is almost totally non-critical of bullet/loading.  I have shot at least 6 different bullets ranging from the lyman 457125 up to 540 grain creedmores, and most recently for the past two years a 540 grain NASA monogrove.  All of these bullets are sufficiently accurate to be competitive in long range competition, although they all shoot differently and drift differently in the wind.

It is a 32 inch heavy octagon Badger.  It does not lead, is not heat sensitive, and shows no tendency of any kind to walk, string shots, or otherwise show an inaccuracy pattern of any kind, under any shooting conditions I have used it in.  The barrel can get much too hot to touch and it still shoots well.

This rifle has always shot about 5 inch groups at 100 yards off of the bench.  It will shoot groups under 2 inches off sticks, although not entirely consistently, but enough to have a very noticably smaller group size than off the bench.  It will often shoot smaller groups offhand than it will off a sandbag on the bench.  I have tried it with a single sandbag on the forearm or barrel, sandbag under barrel and butt, and sandbag under butt and my hand in a fist between the barrel and sandbag.  Anytime the bag touches the forend or barrel, accuracy decreases.

Recently, I have shot it a lot with a .22 insert liner.  It has also been shot a fair amount with the .22 by several other guys at the range.  We have noticed very consistently that it will shoot half the group size or less offhand or off sticks than it will off the bench.  The behavior is exactly the same as when shot with .45-90 loads.

I have been experimenting with trying to decide why this is happening.  The first experiment was in resting point.  It has a very pronounced sweet spot, where it must be rested off of sticks, about 3 to 4 inches from the muzzle.  This rest point will always be the most accurate off of sticks.  Resting this point on the sandbag will result in the same impact point on the target, but results in group size twice as large as off of sticks.  Moving the sandbag back on the barrel keeps the groups large, but moves the point of impact around by 4 to 6 moa on the target.   Moving the sandbag under the forearm moves the point of impact back to the stick position, but results in about the largest group size of any rest point.  That doesn't surprise me, as that's what I would expect from this type of rifle.

Today, we tried it in a Lead Sled type rest with .22 lr.  This resulted in groups approximately 3 times the size of those off of cross sticks.  In fact, I was able to shoot essentially equal groups offhand.  Ignoring about 3 out of 10 called flyers, I could shoot smaller groups offhand.

When shot from the bench, using both elbows on the bench and a hold similar to offhand on the junction of forend and receiver,  it shoots the smallest groups of any position or rest.   Similarly, putting a fist between the sandbag and barrel improves the groups a lot.

There are two things I haven't tried:  Shooting without the forend, and shooting from a Vee rest made of wood off the bench to resemble cross sticks.

I'm not really trying to cure a problem here, as there is none.  The rifle works exactly as it is intended to, and is good at it.  I have no intention of using it as a bench rifle.  But, in the interest of trying to learn something, I'm interested in what makes it behave this way.

Give me your experiences with this, and things I should try to gain more understanding of what's happening.  It's got me curious.


Thanks,
dave

Give you two examples, just like yours.

Anschutz smallbore prone rifle groups prone with coat glove sling off a mat are much smaller than bench rest.  CPA with Pope type stock, accurate rifle offhand but have never shoot good groups prone.

Same thing with both guns, I never shoot benchrest and am not good at it.  This complicated by either rifle not being stocked for bench shooting.  It may look solid but round bottom forends buttstocks that have curve don't shoot well off bags.   Another factor is rested most people don't pay careful attention to conditions like they do when shooting there normal match.  You are focused on something unfamiliar and let other things go 

Bench is a separate sport and the optimal set up is very different than position rifles.  Speculating only in the case of your 45/90 I would guess it's the way the rifle recoils.  No doubt a person could learn to get recoil off mechanical bench rest under control and shoot tight groups. With much time and effort.

Boats

I’m primarily a benchrest shooter shooting traditional schuetzen type rifles and a few large bore long-range rifles.  Over the years I have developed a system that works for me when shooting from the bench.  When I get a new rifle I try it rested on the forend but that never has worked as well as from the barrel.  I use what I believe is called a “Brick” bag for the front. This is a flat bag with square sides and I fill it as full as possible so it’s very hard. I slide the rifle barrel forward on the bag until the forend just touches the bag.  Rear bag is a typical benchrest “V” top bag controlling vertical movement of the rifle with the left hand squeezing the rear bag. Cheek just touching the stock.

ssdave wrote on Jul 15^th, 2008 at 9:39pm:


Free-floated? Not exactly apples-to-apples if so.

Also, what sort of thread engagement and shoulder/receiver ring bearing does your single shot have? Your phenomenon sounds like a vibration issue to me. Have you tried hanging a lead weight on a string from the muzzle? Or sliiiide on one of those rubber fetish-looking dampener/tuner things I see sometimes, just to see if it makes a difference?
Just a thought, Joe

Just something I thought might dampen the vibrations a bit, no history of success, just an idle thought. Would probably work better with a big piece of rubber instead of string, tied tightly.
Regards, Joe

Didn't have enough time to experiment with bench cross sticks or anything else today, but did get to the range to shoot.  Tried some different ammo, not match grade, but different.  This ammo shoots off the bench okay.  It is still very position sensitive to rest point.  Today, the best results came from a single rest point on the front bag, and holding the butt of the rifle on the shoulder without bag support.  The conclusion I'm coming to very quickly is that there are too many variables, and not enough time to experiment to differentiate between some of the cause and effects.    

Here's the last two 5 shot groups of the day that I shot one, and my friend shot the other.   We move the sights 2 minutes of windage and shoot on the same target between painting it.  My group is the one to the right of the dime.  4 in a quarter inch area, then one flyer 1/2 inch away.   More about the shooting results below.

(You need to Login or Register to view media files and links)

I shot two groups in good wind conditions.  One was this one, and the other was less than 1/2 inch.  The flyer on this one was when the wind came up about 1 or 2 mph from behind us, and lifted the bullet.  We called the wind change just as the shot was fired, and the effect was seen here.  I shot several other groups that were in the 1 to 1 1/2 inch range.  Wind conditions were switching directions with a consistent speed of about 2 or 3 mph.  Most of the groups were shot without regard to wind, except if it noticably was enough to blow the shot off the steel, where we would hold up and wait.  We instead concentrated on calling where the shot would go with the wind, holding the same sight picture and seeing how the bullet moved.  It's my way of trying to learn more about the wind calls.

The other group in my picture was shot by my friend in similar wind conditions to my group.  He was experimenting with different resting points on the barrel, and can move the point of impact by an inch or more at will by moving about 2 inches on the barrel resting point on the bag.

It'll be interesting to see if todays results will carry forward to future sessions, or if they are a fluke.  We shot about 100 rounds today, with typical results of less than 2 inches for 5 shot groups all day, and less than 1 inch with consistent winds.    I'm going to shoot a couple of bricks of it and see if the results carry forward.  I'm also going to try to weigh a quantity of them, and see if some are light.  We had three rounds that made less report, and fell about 6 inches or more low on the target.  If I could eliminate those by weighing, this would be great ammo!

dave