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Posted: 4/11/2013 12:46:52 PM EDT
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Mods-please feel free to move if in the section!
I just got a bushmaster 20 inch reg barrel flat top rifle 1/9 I had the smith mount to it a new Nikon p-223 scope with the nikon mount I provided the smith with 30 rds of Winchester 5.56 Q3131A The smith sighted it in and advised that I would be 'on the paper' at 100 yards I have only had the opportunity to shoot it once and with these conditions: Range 100 feet Shooting 5 deg down hill Temp 80 deg From a rest with Q3131A ammo I understand these are not the best conditions, but I had to let my BL shoot today to please the wife :( I am shooting 12 inches high when holding dead center on the bull and 3 inches left at 100 ft Question: 100 feet is not 100 yards, but this is the best range I will be able to shoot at for a while yet Can I assume that the smith was right and I should be on the paper at 100 yards? (Note: BL's group-about the size of a half dollar from a new shooter!-he was happy) Additionally: I want to be able to move that point of impact right three inches-My scope reads '1/2 inch at 100 yards" How many clicks would get me to center-if I have the group as noted at 100 ft? This 100 ft is a pain in the ass but it got me a little range time! and I don't know when I can go out again I want to be reasonably certain I am in side 6 inches at 100 yards-and the smith was right when he sighted it in, and that I can move that group 3 inches right Any help would be greatly appreciated! Sinjin |
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Ok, let me see if I understand this correctly.
100 ft, is about 33 yards. You have a 20 inch barrel firing M193 type ammo. You are 12 inch high and 3 inch left. I don't think you will be on paper at 100 yards. If you are Point of Aim (POA) Point of Impact (POI) at 36 yards, you would have close to a 300 yard zero. I believe you will be very high at 100 yards, you may wish to dial in an adjustment down. If you have 1/2 inch clicks at 100 yards, at 33 yards they will be 1/3 of 1/2. AKA 1/6 of an inch. So 6 clicks will move the impact 1 inch at 100 feet. Your mileage may vary. |
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you would be crazy high at 100 yards
you need about 18 clicks sideways and 72!?!?!?! down you also should take a look at what the paralax is with your scope and ensure consistent cheek weld and sight picture. The smith may have bore sighted it, you may be using a very different cheekweld and sight picture than the smith was. you may also be resting the barrel on something possibly even while pushing down on the rest of the gun which would throw your shots higher. |
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Go back and get your 30 rounds back. No way he ever shot that. Probably did a crappy job with a bore sighter and said you were GTG.
I always seem to remember that at 25 yards you should be shooting something like 2" low. (The difference between your scope centerline and the barrel centerline.) |
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Sorry for the late reply, range was trashed in two storms, got it cleaned up, heavy weather and trashed again!
Thanks for the help guys, I was able to sight in with only 11 rds, still needed to dial it in, I am shooting nickle sized groups at 36 yards with Q3131A! Any one know where I can find a good balistic chart for drops starting at 36 yards and out? 
I would really really like to get a 50 yards zero, but range, time and wife politics are keeping me at the range I have access to ,and that 36 yards! |
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26 yds = roughly 225 yds. Depending on which bullet weight you are using, At 100 yds the bullet would still be high (bullet is still in upward arch @ 100 yds. There is a book called the target book which is very helpful in getting this all down
target book This book was designed for big game hunting but the information is equally adaptable for your application. It really helps remove the guess work and saves ammo |
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This FM has the bullet trajectory for 5.56MM 55gr and 62gr;
http://www.usanato.army.mil/content/documents/bde/safety/safety_pubs/FM3-22-9.pdf |
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I've been reading up some on the military's movement towards the 25/200m zero. Which I may re zero for it; currently I am zeroed at 25/300m zero, and I'm just learning the bullet trajectory of a 5.56NATO round to know where to aim anywhere from 0-300m. Which will be much easier once I get an ACOG to adjust for bullet drop.
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA557028 |
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Quoted:
(snip comments) I would really really like to get a 50 yards zero, but range, time and wife politics are keeping me at the range I have access to ,and that 36 yards! There are "compensated" targets available that will allow you to shoot at 25 yards and yields a 50-yard zero: Comp'ed Targets. They are for carbine-length barrels, but should get you in the ballpark with your 20. They're also really easy to use: fire three rounds from a rest, average the group, count the clicks shown on the side and bottom/top to zero, dial it in a confirm. The height of your scope above the rail will also matter, but it should "ballpark" and you can dial in better when you can get to a real range. Enjoy. GSM |
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