My eyes just are not as young as they used to be so after frustration at the last Appleseed I've mounted a scope on the Ruger 10/22.
After mounting the Nikon Prostaff scope I used an in-the-bore laser sighter to adjust the scope's cross hairs at 25 yards. All looked well.
I then proceeded to shoot groups of 3 shots to finish the job and when I had the three shots spaced aroung the bulls eye, I stopped.
As a curiosity I put the laser back in and found the cross hairs to be about 3 inches low, but found the scope to be accurate when I once again fired three more test shots.
I always assumed a 22 lr was pretty flat out to about 50 yards, but this couldn't be true if the laser does indeed project a straight line of light.
Totally confused, I set out to search for an answer. Thanks God for Google and the internet.
One discussion of the flight of the 22 LR bullet showed a graph of the bullet at various yardages out to 100 yards.
I'll provide a link if I can relocate it.
http://www.gunsmoke.com/guns/1022/22ballistics.html
It essentially showed the bullet was 1/2 inch high at about 20 yards and 1/2 inch low at 66 yards. The discussion assumed a 1 inch target area as I recall.
This shows the bullet to be a little high at 25 yards, but not 3 inches. What am I not seeing? Why are the laser and the bullet this far apart?
At least now the bullets hit where the cross hairs touch IF I can hold the rifle steady!
TNX,
Gary
All a bore-sighter is good for is to get you on paper(MAYBE)
I have seen the times when even that didn't work at 100 yds, at 25 they are OK.
Too many things go on when firing that the bore-sighter can't account for.
+1 Ken.
Using PointBlank software and "guestimating" at the values for .22LR (.120 BC, 1200fps, 36gr) with a scope/bore height of 1.5 inches, I show a zero at 25 yards, .25 inches high at about 40 yards, zero again at 50 yards, and 6.1" low at 100 yards.
It rainbows quite a bit even in the first 50 yards... coming "up" 1.5" in 20 yards, then losing it and going back to zero at 50. That's three inches right there that would differ from a laser.
It isn't real useful for actually practicing ballistic compensation for long range shooting with .223, .308 or .30-06, IMO. it gets shoved around by the wind and gravity A LOT in comparison to these other rounds.
When boresighting at short ranges the main difference in elevation is due to your scope height in relation to your bore as AZRedhawk44 mentioned. And as Ken Grant says - it really is only good for getting you on paper.
Also, for some reason a lot of the laser bore sight devices yield poor results. At a range where I work on several occasions folks have struggled to use one, with no acceptable zero at the end. On the bolt guns, I remove the bolt, look through the bore with a Mk. I Mod. O eyeball, and get the thing within 2-4" at 25-50 yards. It's simple and usually works.
I know, doesn't work with a Ruger 10/22 or any rifle without direct bore access.
The point here is that many folks either don't use these laser gadgets correctly, or the devices themselves are insufficient, or both.
Well, any boresight's function is to get you on the paper at 25 yards so it did its job. The instructions do tell you to go to the range and finish the job.
Thanks for the info on the ballistics software. I've downloaded it and will play with it.
Gary
Quote from: Simballo on October 18, 2007, 10:54:27 AM
After mounting the Nikon Prostaff scope I used an in-the-bore laser sighter to adjust the scope's cross hairs at 25 yards. All looked well.
I then proceeded to shoot groups of 3 shots to finish the job and when I had the three shots spaced aroung the bulls eye, I stopped.
As a curiosity I put the laser back in and found the cross hairs to be about 3 inches low, but found the scope to be accurate when I once again fired three more test shots.
It has to do with barrel vibrations. When the rifle fires, the shock created by the explosion causes the barrel to vibrate. This means that with the rest of the gun at rest, the end of the barrel is doing a hula dance while the bullet is moving down the barrel. Where the bullet strikes the target depends upon where the barrel is in its movement at the instant it leaves the barrel.
A different cartridge with different powder burn rates, different bullet weights ect. will result in vibrations of a different frequency and amplitude. This can and frequently does cause the bullet to exit the barrel pointed in a different direction.
Fire several different cartridges in your 10/22 and your groups will not only vary in size, but at different points in reference your aiming point that are out of proportion to bullet drop.
My feeling is that 3 inches at 25 yards is an extreme example. It might be worthwhile to check the V block screws to be tight. Go easy here. I believe 60 INCH lbs is the proper number.
After carefully zeroing the scope at 25 yards for last weekends Appleseed in Evansville, IN, you can imagine my surprise when I inspected my first 10 rounds on the 1 inch square zeroing target and I was 5 inches low!
Guy said Looks like you need some IMC!
I guess!
I couldn't believe shooting from a sandbag and shooting from a sling supported hand could be so different.
I'd also changed to a stock with a cheek support for the scope so that too was different.
After the IMC instructions were given (by a physics professor no less) I moved the vertical 32 clicks up and then fine tuned it from there!
I never did shoot the 210, but I did shoot a 201 and didn't get to finish my third session. I ran out of time with two rounds in the mag and one in the chamber. A little quicker and I'd have been over the 210.
simballo, the cheek piece probably made a difference. I've heard it said here that some people have a different "zero" prone vs. standing. It's due to their eye being in a different spot behind that rear sight because their cheekweld changes. You can sometimes see the same thing when somebody shoots the 3rd and 4th stages of the AQT. As they move from one target to the next they may still have a nice group but the location of the group changes as they shift their body. The sights/target "look" like they are lined up but they are slightly off (since your eye is not in the same place in relation to the sights/target). Five inches does seem like a lot.
I get a significant zero shift, prone supported (hand resting on a sandbag) versus prone unsupported (normal prone).
Something like 5 plus MOA, easily.
Bench to prone, could certainly be much more than that.
Quote from: AZRedhawk44 on October 18, 2007, 12:43:58 PM
It gets shoved around by the wind and gravity A LOT in comparison to these other rounds.
Just wanted to chime in that gravity shoves everything around equally. :P
Quote from: crak on November 01, 2007, 05:34:39 PM
Quote from: AZRedhawk44 on October 18, 2007, 12:43:58 PM
It gets shoved around by the wind and gravity A LOT in comparison to these other rounds.
Just wanted to chime in that gravity shoves everything around equally. :P
So, that's what's happening to my waistline.............. ???
Time to start walking on my hands............. ;D
Quote from: Atlas Shrug on October 18, 2007, 01:57:33 PM
Also, for some reason a lot of the laser bore sight devices yield poor results. At a range where I work on several occasions folks have struggled to use one, with no acceptable zero at the end. On the bolt guns, I remove the bolt, look through the bore with a Mk. I Mod. O eyeball, and get the thing within 2-4" at 25-50 yards. It's simple and usually works.
I know, doesn't work with a Ruger 10/22 or any rifle without direct bore access.
The point here is that many folks either don't use these laser gadgets correctly, or the devices themselves are insufficient, or both.
Actuall I have never used any mechanical device to bore sight a rifle.
My method is to mount the scope and place the rifle in my midway Gun Cradle. Then I select some distant object about 100 yards away with bolt removed and boresight by the "eyeball" method. If I'm more than 6" off at 100 my first shot I'm surprized.
Naturally I'm speaking about bolt actions. With semi auto's and lever actions I mount the scope set a target up about 15 - 20 yards away and use the trial and error method. When I'm centered up I move out to where I want to be zeroed, usually 100 yards.
There must be more ways to do it....... So how do you do it?
Quote from: Nickle on November 01, 2007, 02:46:03 PM
I get a significant zero shift, prone supported (hand resting on a sandbag) versus prone unsupported (normal prone).
Something like 5 plus MOA, easily.
Bench to prone, could certainly be much more than that.
Do you have that same shift when using a scope?
Quote from: Nickle on November 01, 2007, 02:46:03 PM
I get a significant zero shift, prone supported (hand resting on a sandbag) versus prone unsupported (normal prone).
Something like 5 plus MOA, easily.
Bench to prone, could certainly be much more than that.
With what rifle? Do you think the stock is flexing when you use a rest?
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With what rifle? Do you think the stock is flexing when you use a rest?
[/quote]
I'd think the stock would flex more with a sling than with the bag/rest.
I did see a 5 inch drop in zero from bag rest to sling. The extra tension on the stock would flex it down and that's what I saw on the target.
I know, with very little pressure, you can flex the neck of a guitar enough to hear the change in tone.
I probably don't put as much sling tension on my rifle as some folks do but it's a .22. It doesn't kick and it shoots reasonably tight groups at 25 m. just fine the way I shoot it (5/8" sling supported prone). I say this because I don't think I "bend" my stock much and I have to wonder why anyone would attempt to put enough sling tension on a 10/22 to "bend" the stock.
Based on some experience with the "optical" alignment bore sighters (those things we used before lasers) I can tell you that you can put enough pressure on a rifle barrel with your finger to move it signifcantly off POA if you contact the barrel nearer the muzzle (the closer to the muzzle the less pressure it takes. So, when you fire from a bench does your barrel touch anything? Does your barrel make contact with the inside of the stock in the barrel channel? Either of these could result in your groups moving.
Sometimes a scope moves a little as it "settles" in (not usually on a .22 though - not the same type of recoil).
Try shooting both ways again and see if your zero moves the same amount.
You guys with POI shift problems at 25 yards, are you using scopes? What kind? I'll bet they're non-AO "big gun" scopes, right?
Ever hear of parallax? It really comes into play with .22s being shot from say 20 yards out to 100 or so.
One of my .22 rifles, I could see a POI shift of 2 inches or more in any direction depending on exactly where my eye was in relation to the scope. I took that scope off that gun and put on a proper .22 scope with AO and the groups tightened right up.
In a semiauto .22 being shot from a stable position like benchrest or slung prone, you can also have tight groups but each group seems to be in a different place. That's another symptom of parallax.
Quote from: Simballo on November 03, 2007, 02:17:50 PM
With what rifle? Do you think the stock is flexing when you use a rest?
I'd think the stock would flex more with a sling than with the bag/rest.
I did see a 5 inch drop in zero from bag rest to sling. The extra tension on the stock would flex it down and that's what I saw on the target.
I know, with very little pressure, you can flex the neck of a guitar enough to hear the change in tone.
I know one Guitar Pro who bends the neck instead of mounting a whammy bar.
He played lead Guitar for Jean Sheppard several years (yep, the one from Nashville).
Folks,
I heard the "B" word and thought I'd chime in.
The attached PDFs came from my buddy's Sierra program.
Trajectory for CCI Std, MiniMags, and Stingers are included.
It should get you on paper at distance.
sk