55 & 69 gr trajectory

[outerlimits]

ok...zeroed my 20" ar at 200 w/55 grain stuff...shot 69smk's and they were exactly 2" low at 200. no problem, dialed in 8 clicks into my trust leupold and it's now zeroed at 200. so, at 300, how much difference will i likely see between the 55's and the 69's? i'll be testing this myself in a week or so...was just wondering if someone has already done this...

[uscbigdawg]

outerlimits,

If I knew what velocities you were running, I could tell you what yours would do.

That being said, an investment in good ballistics software is probably not a bad idea. At SMM3G, the range finders were out in force, so we all got a pretty good read on the distance. One thing that I left behind (that thankfully didn't come into play) was my PDA w/ the Horusvision ballistic maps on it. Had I had it, I could just pull up my chart for that load, and it would tell me what my hold over would be (I don't like taping charts to my rifle...it's a vanity thing). Thankfully it wasn't totally needed as on our 300 yard shots, I just held about 4-6" high and drilled the two 300 yard flashers.

Rich

[George]

55gr is gonna drop 5.5-7 inches depending on velocity. The 69gr is gonna drop 7-9 inches depending on velocity. Typically, you would hold at the top of a 12” steel plate with 55gr ball and just over the top with a heavier .223 round.

Of course, things start to really go downhill after 300 yards (that’s a joke). The 69gr is down four more inches at 325 yards and four more at 350. After that it’s basically an express elevator to the basement. You are down another two feet by 450.

--

Regards,

[ErikW]

Bullet Weight: 55 grains

Muzzle Velocity: 3100.0 ft/sec

Zero Range: 200 yards

Range Velocity Energy Momentum Drop Windage Lead Time

(yards) (ft/sec) (ft-lbs) (lbs-sec) (inches) (inches) (inches) (sec)

100 2713.5 899.2 0.66 1.1 1.2 18.2 0.103

200 2347.8 673.1 0.57 -0.0 5.2 39.1 0.222

300 2012.3 494.5 0.49 -7.5 12.6 63.4 0.360

400 1707.4 356.0 0.42 -23.6 24.1 92.0 0.522

500 1440.3 253.3 0.35 -51.8 40.9 125.7 0.714

600 1225.0 183.2 0.30 -96.8 63.8 165.6 0.941

Bullet Weight: 69 grains

Muzzle Velocity: 2800.0 ft/sec

Using same zero as per above 55gr (not re-zeroed for 69)

Range Velocity Energy Momentum Drop Windage Lead Time

(yards) (ft/sec) (ft-lbs) (lbs-sec) (inches) (inches) (inches) (sec)

100 2509.6 964.9 0.77 0.5 1.1 19.9 0.113

200 2229.9 761.8 0.68 -2.0 4.7 42.2 0.240

300 1967.6 593.1 0.60 -11.5 11.1 67.5 0.383

400 1725.7 456.3 0.53 -30.1 21.0 96.1 0.546

500 1507.3 348.1 0.46 -60.4 35.0 128.9 0.732

600 1318.9 266.5 0.40 -106.1 53.7 166.4 0.946

Edited June 10, 2004 by Erik Warren

[Run n Gun]

ok...zeroed my 20" ar at 200 w/55 grain stuff...shot 69smk's and they were exactly 2" low at 200. no problem, dialed in 8 clicks into my trust leupold and it's now zeroed at 200.

Are you sure? Did you shoot again to confirm? I ask this because 8 clicks should move the point of impact 4 inches (at 200) not just the two inches you wanted.

For those truly anal among us, the numbers go:

100 yards MOA = 1.0471966

200 yards MOA = 2.0943232

8- 1/4 minute clicks = 2 MOA, 2 MOA @ 200 yards = 4.1887866"

Ask me how I learned THIS lesson…

Ed

[sargenv]

ok...zeroed my 20" ar at 200 w/55 grain stuff...shot 69smk's and they were exactly 2" low at 200. no problem, dialed in 8 clicks into my trust leupold and it's now zeroed at 200

Um.. 8 clicks? at 200 yards? Shouldn't you have put in only 4 clicks at 200 since most clicks are 1/4" @ 100 and 1/2" @ 200? Or is your scope 1/8 MOA @ 100?

Vince

[lmccrock]

I guess you folks are lucky. When I change from 55 to 69, I have to change both windage and elevation to get a zero. That is on 2 different guns, iron sight service rifle and "tactical class" for 3-gun. So the highpower rifle is set for the 69's and 3-gun for 55.

Lee

[ErikW]

lmccrock, strange thing I found recently is that Hornady 55 FMJ shoots 6 moa windage off the POI of Remington 55 FMJ, Nosler 69, Sierra 69, and Nosler 77. Maybe you can just try another 55 gr bullet.

[lmccrock]

Erik, thanks for the tip. But first I have to find a corner in the new house, put together a reloading bench, unpack the stuff, etc. It is going to happen, just slowly right now.

Lee

[SVI4ME]

I was zeroed for 200 with 55's. I switched to 69's and zeroed again. I just had to move over to the right 2" at 200. I shot at a 8" paper plate at 300 and I hit all shots with 55's and 69's. Just have to put bottom of my donut on center of the plate. I LOVE MY JP ULTRA LIGHT BARREL !!!!! With my other barrel I had different POI with 69 and 55's of 4" up and 2 " over at 200.

I think I'm ready.... I think I'm ready.... repeat, repeat.