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
|