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one of us |
Most folks zero hunting rifles like benchrest rifles--with the fore-end on a sandbag on a rest, and the stock on another sandbag, with the trigger hand doing its thing, and the off hand squeezing the rear bag. I understand this will give the best test of pure mechanical accuracy. But for a hunting rifle, do any of you zero with the fore-end supported by your hand on the bag, or anything else that will reduce the possibility of upward or lateral movement? Or, do you use different techniques for different guns? I read some writer who suggested that for pump-action rifles and slug shotguns, the fore-end should be gripped with the hand, and I've found this to be helpful with my 870. Similarly, Dave Scovill says he tests lever-action rifles with the front bag under the receiver to reduce vibrations through the barrel bands and magazine tube. John | ||
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one of us |
I'm sure my bench technique is partly to blame but if I don't hold onto the foreend I get a LOT of muzzle jump and poor accuracy. I now generaly zero by resting on the wing mirror and door of my car and holding onto the fore end. I generaly check zero in this fashion on a rabbit at 150 - the perfect confidence booster that also keeps the farmer happy (but not at 6am!) | |||
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Moderator |
John, You are absolutely right. Many, if not most, people do sight their rifle in under conditions that will result in a different POI than they will experience in the field. The phenomenon you are referring to is generally called "barrel time". That is, the time the bullet is in the barrel, while it is recoiling. Recoil begins the instant the powder and bullet begin to move. The greater the recoil, the greater the effect of barrel time on POI. For instance the change in POI of a .243 with an 85 grain bullet between "free recoiling" (no hand on the forestock or barrel) and shooting with a supporting hand on the forestock, is quite small. Try the same thing with a .300 Mag and you'll see a substantial difference (a couple inches at 100 yards). Stock design also makes a difference. For example, Weatherby stocks cause greater muzzle lift than straight stocks, and as a result will have a greater impact on vertical movement of POI. I usually do load testing and sighting in using the "free recoiling" technique, as it is the most accurate (removes more human variables). Then I practice from different shooting positions to note the change in POI. All shooting positions will vary. For instance, off hand shooting will result in more muzzle lift than shooting from a sitting position (at least for most people -- everyone is different) because your shoulder will have less give when sitting down and leaning in. In the field, I try to use a rest if possible. From that rest I will try to shoot "free recoil" whenever possible. That's when I know I am most deadly. If that is not possible, however, I use whatever technique is most fitting of the situation, but I have a good idea how that will effect POI (it will always be lower) from my practice at the range. Regards, Canuck [This message has been edited by Canuck (edited 10-09-2001).] | |||
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<Loren> |
Worst experience was in the Army. Zeroed off the bench. Shot for qualification using sling for sitting and standing positions, moved the POI enough to nearly cause me to fail. Using real guns I've not had nearly so much trouble. One benefit of a free floated barrel is that sling tension should have little impact. | ||
one of us |
I do all my testing off the bench...When I'm finished I shoot holding the gun as I would in the field with hand under the forend and no rear rest, most of the time its the same, on ocassions there is some slight variance... I never leave the range without practicing some off hand shooting, say 10 shots at least. ------------------ | |||
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one of us |
I zero my rifles with the forearm supported by my hand which rests on the bag. | |||
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one of us |
Hello John Most of the time I hunt western states, and shoot off a fanny pack that acts much like the sandbag I use at the range. I shoot prone when I can, sitting if need be. POI has not been a problem. Tom | |||
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<BillC> |
Unless you grip the forend tightly during field positions/field situations, there isn't much difference at all. Just remember to always pad the forend with something, whether it be a hat, hand, daypack, etc. The only way to tell how much difference is to shoot it and see. | ||
<R. A. Berry> |
I always grip the rifle with both hands even when shooting off the bench. The bags merely eliminate the wobble of the offhand shot. The big bores that I get a kick out of must be held onto. Even my 223 single shot works well with a death grip at the bench, and my offhand grouping seems to be where sighted in from the bench. I have never busted a knuckle on a trigger guard nor broken the skin of my forehead from a scope bite...knock wood I think you can mimic the dynamics of the offhand grip even when shooting from the bags, and have minimal POI shift between the two techniques. That 0.147" 3-shot group at 100 yards with the GS Custom FN (380 grain) and 105 grains of H 4831 (2509 fps) was shot from the bags and a death grip with both hands, on the Ruger 416 Rigby. The same load and rifle drilled a cape buffalo heart dead center at 75 yards off shooting sticks, with both hands gripping the rifle tightly, forearm tip only lightly supported by the crotch of the sticks. Works for me. ------------------ | ||
<Mike M> |
My experience from centerfire rifle silhouette matches is that there is very little difference between my benchrest zero and my off hand zero. The off hand zero being slightly higher. That is with a 10 lb. rifle in 7 BR -- heavier recoiling hunting weight rifles tend to magnify this some but not all that much. The problem is that hunting situations call for all different shooting positions and POI is going to change a little with each change in position. But in most instances not enough to worry about. I recommend sighting in off the bench to eliminate as much pilot error as possible and then trying various positions to see what effect, if any, they have on POI. | ||
<Ol' Sarge> |
All my hunting rifles are Rem 700s and have a pressure point under the barrel. There is no difference in POI between bench rest off the bags or any other position. I sight my rifles in using sand bags and then shoot a couple boxes using field positions. ------------------ | ||
Moderator |
quote: IMHO this is the best way to eliminated POI shift. I think a lot of people do this without thinking of it. At the range I don't see too many shooter that let their rifle free recoil from the bench. Almost all of them have their non-trigger hand on the forestock, barrel or even the top of the scope when sighting in. By controlling muzzle jump in this manner, they are unwittingly mimicing off-hand or field position shooting and will see little change in POI. The best example I can think of that demonstrates the effect of barrel time, is the addition of a bipod to a sighted in rifle. By adding weight to the fore-end of the rifle, muzzle jump is reduced and POI generally shifts downward. FWIW, Canuck | |||
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One of Us |
I agree with Ray. When dialing in a gun or load I want to remove as much of human error as possible, then in practice I try to duplicate actual hunting techniqe. They are 2 different modes. Also practice is more important than techniqe IMHO. | |||
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<R. A. Berry> |
Right on, Canuck. And the lighter the rifle, the more effect the bipod will have. ------------------ | ||
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