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11/20/2019 5:07:11 PM
Posted: 10/27/2013 7:42:24 PM EST
[Last Edit: 10/27/2013 8:16:54 PM EST by TrooperKbC]
MOLON posted a great thread with a plethora of info about trajectories, but the entire thread focused on 20 inch barrels. Any ideas where to find a similar set of data for the 14.5" carbine, or an image with the 25m trajectories of M855 and M193 (and ideally also MK262) such as this:

Link Posted: 10/27/2013 9:52:14 PM EST
I chose to use MK262 as my "duty" round. The trajectory interests me as well. Next time I head out to the range I'll shoot MK262 out of my 14.5" barrel. However, I am using a 200 yard zero because that's what the calibrations of the reticle are set up for on my Mark 6. I just had knee surgery this week so I'm not sure if I'll be up for hitting the range this weekend. But I'll do it once I'm up for it. Also, the range I shoot at only goes to 300 meters. So my data will only go out that far. Depending on the data, we might be able to extrapolate beyond 300 meters. I might need some math geeks to help me out with this though.
Link Posted: 10/28/2013 3:45:19 AM EST
[Last Edit: 10/28/2013 3:46:38 AM EST by lasnyder]
it would help to chronograph you particular rifle, be it 14.5" or 22"... and to know the ballistic coefficient of the projectile...once it leaves the barrel, gravity is doing its thing to produce trajectory... the vertical acceleration increases as a function of the square of the time it falls.... (d= 1/2 at^2)... the older Hornaday reloading manuals had tables calibrated to velocity and ballistic coefficient, (how well the bullet moves through the air)
Link Posted: 10/28/2013 4:17:08 AM EST
[Last Edit: 10/28/2013 4:18:20 AM EST by jukeboxx13]
There should not be much difference between a 14.5 and a 20 inch barrel, but I am still new at this too so don't quote me.

ETA: That thread shows a 16 inch barrel which will be pretty much exactly the same as a 14.5" barrel.


Link Posted: 10/28/2013 4:25:47 AM EST
I'd love to see a master chart of peoples barrel lengths, twists, brands, ammo used, etc. Especially for those with non-standard lengths like my 12.5, 11.5's, 13.7's, etc. Sounds like a post for the ammo forum...
Link Posted: 10/28/2013 6:48:55 AM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By lancecriminal86:
I'd love to see a master chart of peoples barrel lengths, twists, brands, ammo used, etc. Especially for those with non-standard lengths like my 12.5, 11.5's, 13.7's, etc. Sounds like a post for the ammo forum...
View Quote



Barrel length M855 bullet velocity

210 mm (8.3 in) 723 m/s (2,372 ft/s)
240 mm (9.4 in) 764 m/s (2,507 ft/s)
270 mm (10.6 in) 796 m/s (2,612 ft/s)
300 mm (11.8 in) 825 m/s (2,707 ft/s)
330 mm (13.0 in) 843 m/s (2,766 ft/s)
360 mm (14.2 in) 866 m/s (2,841 ft/s)
390 mm (15.4 in) 878 m/s (2,881 ft/s)
420 mm (16.5 in) 892 m/s (2,927 ft/s)
450 mm (17.7 in) 906 m/s (2,972 ft/s)
480 mm (18.9 in) 915 m/s (3,002 ft/s)
508 mm (20.0 in) 922 m/s (3,025 ft/s)

Use the above info to plug into This

I've used this particular calculator with great success in reloading/shooting for various distances with a .260 Rem bolt gun, even without a chronograph. Familiarize yourself with it and if you have questions or run into problems just ask and we'll work through them.
Link Posted: 10/28/2013 8:08:01 AM EST
[Last Edit: 10/29/2013 12:52:25 PM EST by TrooperKbC]
I got off my lazy butt and did a crude graph myself. I like the idea of collecting data for various barrels, but I'm also not sure if there's enough velocity increase between 14.5" and 20" to make a noticeable difference. I expected the trajectories to only be similar from a longer barrel.

Full Size Photo


ETA: if anyone can find the M193 G7 BC, I'll add that trajectory to the graph!

ETA2: it has come to my attention some of the data in this graph may be incorrect. please follow the most current posts for updates.
Link Posted: 10/28/2013 10:01:24 AM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By TrooperKbC:
I got off my lazy butt and did a crude graph myself. I like the idea of collecting data for various barrels, but I'm also not sure if there's enough velocity increase between 14.5" and 20" to make a noticeable difference. I expected the trajectories to only be similar from a longer barrel.

Full Size Photo
http://i223.photobucket.com/albums/dd203/4r00p3r/M4Traj_zps4697f739.png

ETA: if anyone can find the M193 G7 BC, I'll add that trajectory to the graph!
View Quote
I can't tell where the zero is and It needs distance in between lik 25/50 yards for example.
Link Posted: 10/28/2013 12:46:56 PM EST
[Last Edit: 10/30/2013 10:08:41 PM EST by TrooperKbC]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By jukeboxx13:
I can't tell where the zero is and It needs distance in between lik 25/50 yards for example.
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By jukeboxx13:
Originally Posted By TrooperKbC:
I got off my lazy butt and did a crude graph myself. I like the idea of collecting data for various barrels, but I'm also not sure if there's enough velocity increase between 14.5" and 20" to make a noticeable difference. I expected the trajectories to only be similar from a longer barrel.

Full Size Photo
http://i223.photobucket.com/albums/dd203/4r00p3r/M4Traj_zps4697f739.png

ETA: if anyone can find the M193 G7 BC, I'll add that trajectory to the graph!
I can't tell where the zero is and It needs distance in between lik 25/50 yards for example.


As stated in the OP, the zero is 25 meters. Since there are 5 segments to each 100 meter distance listed at the top of the graph, that makes each line 20 meters apart. I can add those details to the graph, but you can see the major axis are already designated and the bullets all pass the zero line at 300 meters and somewhere just after 20 (which is 25). I'll be glad to add those upgrades when I add the M193 G7 line...as soon as I get the G7 BC.

ETA: Just found this chart here. I'll update the full size graph ASAP.

Source ... Diameter ...Weight ... Type ... SD ... BC
APG G7... 0.221 ...53.5 ... 5.4 Sov ...0.16... 0.168
APG G7 ...0.224 ...55 ... M193 ...0.16 ...0.12
APG G7 ...0.224 ...62 ... M855 ...0.18 ...0.151
APG G7 ...0.224... 62 ... SS109... 0.18... 0.158
APG G7 ...0.308... 149 ... M80 ... 0.22 ...0.2
APG G7... 0.308 ...168 ... M852 ... 0.25 ... 0.215
APG G7 ...0.308... 173 ... M118 ...0.26 ...0.24
APG G7 ...0.308 ...190 ...Sierra MK ...0.29 ...0.252
APG G7 ...0.308 ...123 ...7.62m43 ...0.18 ...0.156
APG G7 ...0.510 ...650 ...M33 ... 0.36 ... 0.34

The M2 ball is a "G8" model:

APG G8 ...0.308 ...152 ...M2 (G8)... 0.23... 0.21
Link Posted: 10/28/2013 1:07:33 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By lasnyder:
it would help to chronograph you particular rifle, be it 14.5" or 22"... and to know the ballistic coefficient of the projectile...once it leaves the barrel, gravity is doing its thing to produce trajectory... the vertical acceleration increases as a function of the square of the time it falls.... (d= 1/2 at^2)... the older Hornaday reloading manuals had tables calibrated to velocity and ballistic coefficient, (how well the bullet moves through the air)
View Quote


I have a chronograph. I can definitely bring that out as well. I do have 16" ARs as well. If I remember, I'll bring one out just to compare velocities.
Link Posted: 10/28/2013 1:10:39 PM EST
Link Posted: 10/28/2013 1:13:10 PM EST
[Last Edit: 10/30/2013 10:10:04 PM EST by TrooperKbC]
Link --> Full Size Graph (updated)



Mod, please feel free to copy or move this thread to the ammo forum if you think it would fit in better there.

ETA: Again, this is a rough draft with likely errors. Please follow the most current post for updates.
Link Posted: 10/29/2013 4:17:10 AM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By TrooperKbC:
Link --> Full Size Graph (updated)

http://i223.photobucket.com/albums/dd203/4r00p3r/M4TrajFull_zps90a9aac8.png

Mod, please feel free to copy or move this thread to the ammo forum if you think it would fit in better there.
View Quote
Interesting that with the ammo you were using comes back to zero at 300 with a 25 zero.
Link Posted: 10/29/2013 10:19:41 AM EST
[Last Edit: 10/29/2013 10:20:43 AM EST by TrooperKbC]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By jukeboxx13:
Interesting that with the ammo you were using comes back to zero at 300 with a 25 zero.
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Discussion ForumsJump to Quoted PostQuote History
Originally Posted By jukeboxx13:
Originally Posted By TrooperKbC:
Link --> Full Size Graph (updated)

http://i223.photobucket.com/albums/dd203/4r00p3r/M4TrajFull_zps90a9aac8.png

Mod, please feel free to copy or move this thread to the ammo forum if you think it would fit in better there.
Interesting that with the ammo you were using comes back to zero at 300 with a 25 zero.


Ahh, yes. I believe this was general military protocol for quite a while. I think some branches have changed that to 33, 36, or 50m, due to modern CQB operations, but I want to say the Army, Air Force, and Navy still use the 25m zero.

Operator's Manual
Link Posted: 10/29/2013 11:22:40 AM EST
[Last Edit: 10/29/2013 11:23:21 AM EST by jukeboxx13]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By TrooperKbC:


Ahh, yes. I believe this was general military protocol for quite a while. I think some branches have changed that to 33, 36, or 50m, due to modern CQB operations, but I want to say the Army, Air Force, and Navy still use the 25m zero.

Operator's Manual
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View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By TrooperKbC:
Originally Posted By jukeboxx13:
Originally Posted By TrooperKbC:
Link --> Full Size Graph (updated)

http://i223.photobucket.com/albums/dd203/4r00p3r/M4TrajFull_zps90a9aac8.png

Mod, please feel free to copy or move this thread to the ammo forum if you think it would fit in better there.
Interesting that with the ammo you were using comes back to zero at 300 with a 25 zero.


Ahh, yes. I believe this was general military protocol for quite a while. I think some branches have changed that to 33, 36, or 50m, due to modern CQB operations, but I want to say the Army, Air Force, and Navy still use the 25m zero.

Operator's Manual
Yea its just weird that in the graph in your OP at 300 meters it was 4-5 inches high.
Link Posted: 10/29/2013 11:30:26 AM EST
Link Posted: 10/29/2013 12:48:46 PM EST
I see now.

Thanks for clearing that up, and man the extra 5.5 inches makes a big difference then.
Link Posted: 10/29/2013 2:05:41 PM EST
I've decided to continue this thread in the ammunition forum in hopes of more discussion and to seek verification of values used in calculations. I found a few possible errors in the data used above, so the new info will be in the new thread. Please follow HERE if you're interested.
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