AR Sponsor
Posted: 12/11/2004 6:17:22 AM EDT
| Hi, I'm new to the forum and acutally new to shooting AR's. I took my new Bushmaster M4 up to the range a few days ago and was kind of surprised at the results I got. I was shooting PMC 55gr. ammo at 100 yards. I was trying to zero in the iron sights, and managed to get the windaged down with no problem. The elevation was another matter. I dialed the sight in the down direction to the stop but couldn't get the rounds to strike less than about 12 inches high on the target. I started aiming 12" below the tartget center and began hitting right-on. What's going on here? Is it the sight? Am I just running into the ballistic limits of the 5.56 cartridge? I looked on the web to try to find a ballistic graph of the 5.56 round, to see if that's just it's normal flight path at 100 yards, but couldn't find one. I'd appreciate any input on this. Thanks. |
Is it an A2 or flat top with BUIS?.If its A2 then raising the front post lowers impact and lowering raises the impact.I would zero at 50 tds and sight it in so you cut the target circle in half so impact is to point of aim.If your resting the post at the bottom of the target circle"lolypoping"the sight picture thats meant more for competition or range shooting.If its a flat top and you are using a BUIS then you will need the .040 higher fron post.Even out a 14.5 barrel you will get the 2700 FPS at 100 tards to keep the rifle using 55 grain belistical deadly for the purpose of defense if needed.A 16" you will get another 40 or 50 yds and a 20" 200 and under.Balisticaly .223 is a very flat shooter and should be fine out to the range you are using,I think its your sights.Give a little more info on the type of sights you are using A2 or BUIS?.
|
Yep.  www.bushmaster.com/shopping/scopes/9349056-m.asp I need one too. On my 20" FN barreled upper I'm using a Colt detachable handle and have the front sight cranked very high. |
| Well, sometimes a problem solves itself if you give it enough thought. The replies on this thread got me thinking about changing the front sight post, so I pulled the rifle out of the safe to have a look. Like I said, I'm new to AR's. It turns out that the front sight post is adjustable (why I didn't think to look at that in the first place - I can only speculate!) It was adjusted for full up elevation. I adjusted it down two turns and took it up to the range yesterday. Definitely better, that brought the point of impact down about six inches. I had no tools to adjust it at the range, but when I came home I adjusted it another three turns. It should be good to go, I won't get a chance to shoot it until next Saturday, but I'm pretty sure that this was the problem. Thank you for your help everyone, you put me on the right track. |
AR Sponsor