I took my rifle out this weekend to practice w/ live ammo before this weekend's Appleseed. I have a scope on my rifle (set at 3x which is the lowest). I put the rifle on sandbags and zeroed the rifle at 25 yards. Then i took it off the sandbags and put the sling on. Tried hasty and web sling setup; I was off by 1 inch. CONSISTENTLY... one inch.
i used an AQT target (top right corner zero spot) and put 10 rounds inside the black dot using sling, once i aimed to compensate for the 1 inch. I rezeroed (using websling) so i didn't have to compensate. Then for snickers i put it back on sand bags to check zero. I was.. off .. 1 inch.. consistently the OTHER direction. I dont remember now if it was up or down; i failed to bring my log book.
My question is... does anyone know what would cause this?
Great question.
It's not unusual to have a different zero from a supported (sandbag/benchrest) position vs. prone with a sling.
You and your rifle work together as a system. When putting your rifle on a rest, you've changed the system and can get a different result.
I hope this helps,
Rusty
We just had this discussion at the Toccoa, Georgia shoot yesterday. We all came to the same conclusion as Rusty.
FabricatorsGal
The THEORY is i wanted to remove the human factor from zeroing the rifle.. instead of chasing it down. Yet another reason to value shot GROUPS then and adjustments as needed; and calling your shot.
I thought at first it was because it was getting dirty.. etc. which is why i put it back on the bag. When i realized i was chasing phantoms, I decided to practice rifleman cadence at a 4 inch gong. Working w/ either zero.
50 shots at a gong, in cadence (w/ exception of magazine changes) was... rewarding.
Thanks for the feedback!
Also in agreement - it's actually common enough that it's unusual -especially with a centerfire - if it doesn't happen.
The pulse of the recoil - even on lightly recoiling rifles - happens while the bullet is still accelerating through the barrel where it can be influenced by rifle motion. How your body (in combination with any additional rest or support involved) absorbs that recoil is a part of your zero. Always set your final zero the same way you plan to actually use your rifle.
Your question has been answered.
I only zero from a bench, to check my handloads, and typically that would be from a Lead Sled, to take "variation....AKA ME" out of the picture.
Zero's will be different if shooting supported/vice unsupported.
Also, of note as well would be if you get a 100 yard zero on a centerfire, shoot it for a day, and then CLEAN it, you may realize as much as a 1/4 minute or more shift on your original zero. Not that big a deal when shooting inside of say 400 yards, but past that it can be a significant zero shift. Since proving this out myself, on a 1000 yard range, I have yet to clean any of my barrels. I do however clean the actions and also the chambers, but the bore stays dirty, my next round cleans it.
I think I have a thread on "cleaning and zero" shifts on here somewhere.
YMMV, to each his own, but....I do not clean my precision instruments barrels. This includes Carbine/Garand/1903A3/1903A4/1917 and also my AR15 SVC rifle and AR10.
My rimfire barrels do however get cleaned after each use, provided 100+ rounds were sent down the barrel.
You can google my cleaning topic, and it is like opening the proverbial Pandora's box. But I have checked with Criterion (most my barrels are Criterion) and they were good with my reasoning.
Now if you use corrosive ammo, you MUST clean. No corrosive ammo for me.
Here is the link about "cleaning or not cleaning"
http://appleseedinfo.org/smf/index.php?topic=45372.msg319745#msg319745
R/
Chris
If you don't have a float tube or free float barrel pressures will be different from sandbag to sling and this will show itself in elevation issues.
Short advice is to get on paper with the bag and then zero in prone (or sitting). It is also not unusual to see minor zero differences between prone, rapid prone and sitting that are not explained by distance differences (in other words there may be both an elevation and windage component to the difference).
I shot a match on Saturday and my sitting zero was 1 moa lower than my standing zero. But I knew this beforehand and adjusted for it. A zero is not a one time event, it is something that changes due to weather, light, clothing, etc.
Go to the Virginia section of the forum and read the Hathcock advice on developing a zero for a hunting rifle.
http://appleseedinfo.org/smf/index.php?topic=21263.0
I believe some of it has to do with the fact your cheek isn't hitting the stock at the exact same angle from one position to another. (Cheek weld IS sight alignment) If your eye isn't in the exact same position and the same distance from your scope, it will cause a difference in your zero. For myself, it's not uncommon to drop shots lower when moving to seated or standing position because I might not be able to get my eye as close or the pressure and angle of my cheek weld is slightly different. Often, the stock on my rifle isn't high enough to place my eye in the proper position for a scope. This causes me to have to raise my check weld slightly higher, rather than mushing it down against the stock. You can mitigate this by putting a stock riser or cheek pad on the stock. The goal is to be able to put your cheek on the stock with your eyes closed, open your eyes and see perfect sight alignment without having to reposition your cheek.
Also, it depends on the type of surface you are shooting from on the bench. There is a certain "bounce" factor which causes the muzzle to jump up away from the surface before the bullet exits the barrel, often causing your point of impact to be high. Sand is going to absorb more energy than wood or carpet covered wood. This is why I prefer to put my hand under the fore-end of the rifle when shooting off a bench to minimize the difference. You might also try not resting the rifle on anything at all, even when shooting from the bench. Put a sandbag under your forearm for support instead of resting the rifle on something. This should give you the extra stability while maintaining much of the other mechanics you can expect in the prone position.
One more thing to pay attention to: The bench is giving you extra stability by minimizing the effects of other things you might be consistently doing wrong such as improper trigger finger placement. For instance, in prone you may be dragging wood, heeling, snatching, or bouncing your trigger finger consistently enough to still shoot small groups, but changing your point of impact when there's no longer a benchrest to control the muzzle.
Since it was brought up, lets discuss cadence.
Cadence is something observed externally. What the shooter should see is good sight alignment and good sight picture. The only thing that matters is how well you shoot and cadence is irrelevant to that. Watch Sheri Gallagher shoot sitting. Does she have good cadence? Does it matter when she cleans the target with a 100-8x?
https://www.youtube.com/watch?v=bI3CNcLDvTs
Next time try your 50 shots on a paper target. Focus first on group size and then on group placement. I'm assuming since you say it was a 4" gong that you were shooting at 100 yards. You can download a 100 yard offhand, rapid or slow prone target from the below sight or you can download 50 yard targets from the Ray-vin sight.
Here's the 100 yard slow prone target.
http://downloads.bisonballistics.com/MR-31.pdf
:pop:
Since I love performance art, I will go further. I once saw the best cadence I had ever seen at an Appleseed. There was a shot every 3 seconds at a KD in a mid-western state that VA Shooter and I were doing. I mean this guy was clockwork perfect.
The problem was he was not paying attention to the important things. What he was doing was taking a shot every 3 seconds regardless of where he was in his breathing cycle or where the front sight was. Any guesses on how that "perfect" cadence turned out.
Now we all know the problem here, but this guy had been taught that he should be breaking a shot "in cadence" every three seconds. He was perfect in that. Sadly the best cadence I have ever seen did not in any way equate to a good 300 yard or 400 yard target.
Remember the 6 steps. Where does "cadence" appear in them?
1. Sight alignment
2. Sight Picture
3. Respiratory Pause
4a.focus the eye on the front sight
4b. focus the mind on keeping the front sight on the target
5. Squeeze the trigger
6. Follow through and call the shot.
The free float barrel makes sense, it's NOT free-floated. Great/simple feedback; use bags/sled for developing hand-loads but then practice how you intend to use it. Simple, true feedback.
I've been shooting for a while; which means i have things to UN-learn.. and i'm stubborn. As for shooting in cadence not being listed for taking "A shot", clearly it's not. There is no cadence to a single shot. However because the intention may seem unclear... it was for practicing on relaxing and enforcing the value of NPOA. It wasn't about just pulling the bang bang switch w/ my booger hook ever X seconds. It was more about being able to stay calm, and RELAXED enough to consistently be on target.
One of the challenges i had during my first appleseed was getting rounds off in time; then i went to the other extreme and didn't shoot in cadence... While it's not 6 parts of taking a shot, I need to bring it to my attention because my problem at the last event was holding my breath to get off 2-3 shots to "make up time" which only made it worse. OR, i would take too much time getting "the perfect shot". So again, it wasn't to shoot every X seconds.. it was more to prove to myself that if shooting in cadence; the NPOA will make a world of difference in constancy and time constraint efficiency.
To see the sight picture float off target, then back on.. naturaly and constantly was a valuable lesson.
This consistency counteracts the time requirements for shooting rapid fire sections of AQT while still allowing the 6 steps. So; is it part of the 6 steps of taking a shot... no. Does it help realize the value of NPOA, and how achievable the time restraints are in an AQT... defiantly. A bad NPOA introduces mussel fatigue while trying to bring it back onto target. This fatigue is prevented.. by practicing NPOA.
Then you have self learned a secret. The secret is that you can only shoot an accurate shot as fast as you can return to Natural point of aim while maintaining sight alignment and using trigger control.
You have a gauge on your rifle that tells you whether you have reached the proper point for respiratory pause. That gauge is the front sight, or the reticle. As long as you have a good position, NPA, sight alignment and good trigger control that gauge will not let you down. You may not be happy with the size of your group "now" but by practicing those things you will improve.