8.5 Inch Barrel Trajectory Chart?

Discussion about rifles in 300 AAC BLACKOUT (7.62x35mm), hosted by the creator of the cartridge.

Moderators: gds, bakerjw, renegade

msualexander
New Member
Posts: 2
Joined: Wed May 13, 2015 12:26 pm

8.5 Inch Barrel Trajectory Chart?

Post by msualexander »

Hey all,

I'm building a 300 Blackout right now and as I'm choosing my optics I did several internet searches looking for trajectory charts for sub and supersonic rounds being fired through an 8.5 inch barrel. I've been unable to find suitable data. I'm thinking of 220 and 125 grain rounds. Anyone have any thoughts? I'll likely zero at 50 meters. Thanks for your time.
MiamiE
Silent Operator
Posts: 54
Joined: Wed May 06, 2015 7:12 pm
Location: South Florida

Re: 8.5 Inch Barrel Trajectory Chart?

Post by MiamiE »

I will be following this thread as well. I will be shooting the 220 subsonic loads but I haven't not decided if the 110 TX or 110 VMax will be best out of the 8.5" barrel.
User avatar
Chedr
Silent But Deadly
Posts: 764
Joined: Tue Jul 30, 2013 10:10 pm
Location: Pacific Northwest Washington

Re: 8.5 Inch Barrel Trajectory Chart?

Post by Chedr »

Tag for interest.
Image
User avatar
dellet
Silent But Deadly
Posts: 6967
Joined: Fri Nov 30, 2012 1:25 pm

Re: 8.5 Inch Barrel Trajectory Chart?

Post by dellet »

You won't find a trajectory chart based on barrel length.

You might be able to find a velocity chart for specific loads or factory ammo shot from a barrel of a certain length. Then you can apply that velocity to a trajectory chart.

The closest you might come to that I know of is certifiable's data in handloading. He has listed loads by barrel length.

For subsonic you could get close knowing that most loads will be in the 1000-1050 range no matter what bullet is used.

To accurately chart your trajectory you will need to know the velocity from your barrel along with the weight and BC of the bullet.
300 Blackout, not just for sub-sonics.
msualexander
New Member
Posts: 2
Joined: Wed May 13, 2015 12:26 pm

Re: 8.5 Inch Barrel Trajectory Chart?

Post by msualexander »

Ok. Then does anyone know of a chart listing muzzle velocity of different grain rounds out of an 8.5 inch barrel? I see how I can use that to calculate the trajectory using an online ballistics calculator. I have found different charts listing EITHER velocity for different grain rounds without mentioning the barrel length, OR velocity per barrel length without mention as to what the weight of the round was.
User avatar
certifiable
Silent But Deadly
Posts: 1766
Joined: Mon Nov 26, 2012 8:14 pm
Location: Kansas

Re: 8.5 Inch Barrel Trajectory Chart?

Post by certifiable »

I typically see a 200 fps drop in velocity with my 110-125gr super sonic hand loads going from 16" barrel down to a 9". For me 110's usually run about 2300 fps(16") and 2100 fps(9"). 125's usually run 2200 fps(16") and 2000 fps(9").
to get an approximate drop chart you can input your values into a ballistics program and that will get you close but nothing will substitute for putting rounds on paper at the various distances you want to shoot.
I run a Vortex viper pst 1-4 MRAD scope with a zero cant mount, on one of my blackouts and have used it to put subs on paper at 500 meters. The scope had plenty of turret adjustment to get the 220gr subs on target without using a holdover. I also have a Nikon BDC scope but trying to remember which hold over at which magnification for for distance with which load is a complete PITA and the BDC was not usuable for me with subs beyond 300yds when zeroing the optic with any practical supersonic zero.
JME for what it's worth
"America will never be destroyed from the outside.
If we falter and lose our freedoms, it will be because we destroyed ourselves."

Abraham Lincoln
TMD
Silent But Deadly
Posts: 1464
Joined: Mon Oct 08, 2012 10:35 am
Location: San Angelo, TX

Re: 8.5 Inch Barrel Trajectory Chart?

Post by TMD »

Barrel length is irrelevant when it comes to subsonic loads. If loaded between 1000 and 1050 fps it's going to be the same trajectory no matter the barrel length. As for supersonic loads all you need is the velocity of your load to calculate trajectory.
rimshaker
Silent But Deadly
Posts: 475
Joined: Sun Nov 25, 2012 2:32 am
Location: FL

Re: 8.5 Inch Barrel Trajectory Chart?

Post by rimshaker »

TMD wrote:Barrel length is irrelevant when it comes to subsonic loads. If loaded between 1000 and 1050 fps it's going to be the same trajectory no matter the barrel length. As for supersonic loads all you need is the velocity of your load to calculate trajectory.
Yea for subs just use the muzzle velocity spec, no matter the barrel length.

But for supers, the general rule of thumb for BLK is 25-30 fps loss per inch of barrel.
User avatar
danner
Silent But Deadly
Posts: 677
Joined: Sat Feb 14, 2015 1:22 am
Location: MI

Re: 8.5 Inch Barrel Trajectory Chart?

Post by danner »

msualexander wrote:Hey all,

I'm building a 300 Blackout right now and as I'm choosing my optics I did several internet searches looking for trajectory charts for sub and supersonic rounds being fired through an 8.5 inch barrel. I've been unable to find suitable data. I'm thinking of 220 and 125 grain rounds. Anyone have any thoughts? I'll likely zero at 50 meters. Thanks for your time.
Are you looking for something like this?

Image
Someone who is ruled by the "discretion" of another is, to that extent, a slave.
User avatar
danner
Silent But Deadly
Posts: 677
Joined: Sat Feb 14, 2015 1:22 am
Location: MI

Re: 8.5 Inch Barrel Trajectory Chart?

Post by danner »

Or this? Which is more like a 25 yard zero.

Image
Someone who is ruled by the "discretion" of another is, to that extent, a slave.
Post Reply

Who is online

Users browsing this forum: No registered users and 124 guests