When will my .223 go transonic?

[J_ROD]

Excuse me if this post is in the wrong section. I have a Savage Model 10 Precision Carbine in .223 with a 20” barrel, 1:9 twist, all factory equipment and no suppressor, shooting factory Hornady Black 75 gr BTHP. The box gives a a velocity of 2790, however, I do not have access to a chronograph to get my actual muzzle velocity. I was out shooting today and had my first chance to shoot that rifle at 700 yards. Had to walk it in but finally got a few good hits on 12” steel. After I was finished I was wondering how far my setup could get before going transonic. Any ideas?

 

[PBWalsh]

http://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi (hit the "Calculate" button at the bottom to show the projected data)

Looks like around 950 yards. This assumes the 2790fps is correct, data shown here is at sea level, 3mph wind.

What is your altitude and what was your DOPE to 700 yards? Asking your DOPE because if you are at sea level and it took you MORE THAN 6.0 mils to impact, then your velocity is lower than 2790; if it took LESS THAN 6.0 mils, then you're going faster than 2790. Altitude dependent of course as higher altitudes have less impact on a bullets trajectory than lower altitudes.

 

[DJL2]

Good work making some hits at a distance that is not trivial the old fashioned way. Take good notes! The only thing better than a good guess (what a ballistics engine gives you) is opening up your log book and seeing exactly the right data ;-).

 

[Dthomas3523]

Approximately 35-45 feet from the muzzle.....

 

[patriot07]

Mine went unstable at 650 yards. Gun just happened to have a slow node, and really didn't shoot anything but the 75 grainers well.

 

[stello1001]

How much elevation did you dial to get center-ish hits at 700?

 

[patriot07]

DOPE is going to be dependent on elevation, barometric pressure, height of scope above the bore, temperature, etc. Someone else's correction won't necessarily be valid for your situation, especially when talking 223 out at 700 yards.

 

[deanq]

OP, Just as a reference point. My 26" 1x7.7 clocks Hornady Black 75gr at 2780 fps. I would think your 20" barrel is a few hundred fps slower. FYI YMMV

 

[Greg Langelius *]

I use my 24" 223/5.56's out to 600yd for trouble free consistency, and go with a 6.5 (mine's a 28" 260) for beyond 600yd. I have zero desire to explore the limits of extended distance-for-chambering accuracy; rather, I desire a slam-dunk shot reliability.

I consider an at-target velocity of 1300fps to be minimum for consistent accuracy. What distance this occurs at will vary quite a bit with altitude. I live and shoot at around 4000 to 4500ft ASL, and wouldn't be too surprised if my same 223/5.56 load was super/transsonic at 1000yd

I'll still use the 260 beyond 600yd

Greg

 

[J_ROD]

How much elevation did you dial to get center-ish hits at 700?

18.5 MOA

 

[J_ROD]

http://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi (hit the "Calculate" button at the bottom to show the projected data)

Looks like around 950 yards. This assumes the 2790fps is correct, data shown here is at sea level, 3mph wind.

What is your altitude and what was your DOPE to 700 yards? Asking your DOPE because if you are at sea level and it took you MORE THAN 6.0 mils to impact, then your velocity is lower than 2790; if it took LESS THAN 6.0 mils, then you're going faster than 2790. Altitude dependent of course as higher altitudes have less impact on a bullets trajectory than lower altitudes.

Thanks for the info. The dope was 18.5 MOA and about 2 MOA for left to right wind. At what range will y’all adjust or calculate for spin drift?

 

[PBWalsh]

Listen to Frank’s podcast, according to him, spin drift is so minimal you shouldn’t worry about it. Besides, you’re shooting less than a mile, don’t worry about it.

 

[Dthomas3523]

Thanks for the info. The dope was 18.5 MOA and about 2 MOA for left to right wind. At what range will y’all adjust or calculate for spin drift?

Once the amount of spin drift is more than what you and/or the rifle is capable of shooting.

Example (making up numbers here)

You are capable of shooting 1moa at 1k.

Spin drift is half an moa.

You have more margin of error in your rifle than spin drift, so it’s pretty negligible.

The short answer: the better PRS shooters around here have it turned off in their kestrel.

 

[J_ROD]

Listen to Frank’s podcast, according to him, spin drift is so minimal you shouldn’t worry about it. Besides, you’re shooting less than a mile, don’t worry about it.

I guess I’ll go ahead and forget spin drift until I get a rifle capable of shooting out to a mile or beyond. Thank everyone for your help. What is the name of the podcast?

 

[PBWalsh]

“The Everyday Sniper”, available on the Podbean app and Itunes. Frank is the host and Mike from MHSA is usually on as a co-host as well. Download them all, starting with the first through the most recent (#125 currently) and listen to them to and from work, or during work depending on what you do. Its free and has a lot of golden nuggets in it. q

There is also a subforum down a bit lower for the podcast. Also check out the online training here if you can swing an extra $15 per month. Its invaluble training and overall definitely worth the money.

 

[Ledzep]

You're probably safe to about 800yd. For stability and staying well supersonic. May be a shorter distance on cold days.