.223 optimum velocity.

[gixer1]

I’m just starting to develop a load for a new .223 with 73gr ELD-M’s, I shot some factory ELDM’s just for zeroing and found they shot very well group wise and not horrendously from an ES point of view….however, the average velocity was round about 2560fps, which seems a little slow but looking at my ballistics calculator it would get me well beyond my intended range for gong bashing…(1070 yards based on my scope elevation - I did not intend to use it much past 700 yards)

So the question remains, do I try to replicate the factory load or speed it up a bit, I guess there isn’t a huge benefit other than reduced wind effect if it’s going a little faster.

Any input welcomed.

Regards,
Gixer

 

[ColinBr]

A bit of speed never hurt anyone mate.

As with any load start a bit below max, and work up till you get the accuracy you are looking for.

I've always found my rifles to like a bit of speed before they start shooting properly

 

[Outback]

Shoot groups on cardboard to find the next node , if you haven't got a crono you could check your velocity with your elevation come ups .

 

[gixer1]

A bit of speed never hurt anyone mate.

As with any load start a bit below max, and work up till you get the accuracy you are looking for.

I've always found my rifles to like a bit of speed before they start shooting properly

That’s just it Colin, it’s shooting pretty well at 2560fps…hence the “what do I gain by pushing it harder”….i’m going to do a ladder test anyway but just curious.

 

[gixer1]

Shoot groups on cardboard to find the next node , if you haven't got a crono you could check your velocity with your elevation come ups .

I’ve got a chrono…and yes, I will do the ladder test and check for nodes based on ES but what’s the gain on velocity…

 

[ColinBr]

Wind with that distance. Id want as much advantage as I could get

 

[ashray]

accuracy counts not speed.

 

[gixer1]

accuracy counts not speed.

That’s kinda what I’m thinking? Is it just a fashionable thing to run faster than needed? Or are wind calls more difficult and unpredictable with slower velocities? I would assume it’s just a case of adding more windage but can’t see why it would be any more irregular?

 

[Laurie]

If it's the 73gn ELD (as opposed to the lower drag 75gn ELD-M), Bryan Litz gives it a G7 average BC value of 0.210. At 2,560 fps MV this combination sees you in trans-sonic speeds before 700 yards, barely supersonic at 800 (1,146 fps vs 1,126 fps for the barrier speed), and subsonic after 800. You need a higher-BC bullet and/or much higher MVs. These figures are for 'standard ballistics conditions' (59-deg F; sea level; 29.97 inches mercury atmospheric pressure). Colder air makes it worse; warmer/higher altitudes make it better.

If the bullet is the higher BC (0.238) longer-nose 75gn ELD-M things are a bit better, giving you an extra 100 yards before hitting each condition, but still subsonic at 1,000 with a calculated 1,061 retained fps.

How individual bullets cope with trans and subsonic speeds / transitions varies considerably. Some like the old 80gn 0.224 Sierra MK cope very well; others become increasingly unstable. Note for anybody contemplating range use of this sort of combination, sound-operated electronic targets such as the Shot-Marker need supersonic bullets at the target to work.

You also need a lot of scope elevation adjustment available. The come-up for the higher BC ELD-M is ca. 43-44 MOA at 1,000; more for the lower BC model.

 

[the prowler]

There's only so much 223rem is going to give you with heavy bullets. What speed you after?

 

[jthyttin]

My 20" AR-15 mag length 75gr HPBT load gives another 90m/s (i.e. 2850fps) and that's with VV powders. There should be comfortable margin for improved speed for OP.

 

[RCS Deer Management]

For those ranges with a .223 you want as much speed as you can get, you will really struggle at the velocity’s you are getting. My mate is running 73gr eld out of his .222 at 2730fps, I would be looking at at least 2700 out of a .223

 

[Outback]

Being a regular shooter at 300/500/600 yards with a 140grn eld-m , the accuracy for consistent hits is substantially improved going from a velocity of 2680 from a 6.5x55 to 2930 fps from a 6.5 prc , both rounds are tuned to a accurate node with Vht 165 .

 

[secondtry]

For those ranges with a .223 you want as much speed as you can get, you will really struggle at the velocity’s you are getting. My mate is running 73gr eld out of his .222 at 2730fps, I would be looking at at least 2700 out of a .223

This. 2560 is ridiculously slow, even if your barrel is a tad slow and only 20"long.

My 22" T3x runs a very easy 2780 with 77gr TMK, and this is not fast.

 

[gixer1]

If it's the 73gn ELD (as opposed to the lower drag 75gn ELD-M), Bryan Litz gives it a G7 average BC value of 0.210. At 2,560 fps MV this combination sees you in trans-sonic speeds before 700 yards, barely supersonic at 800 (1,146 fps vs 1,126 fps for the barrier speed), and subsonic after 800. You need a higher-BC bullet and/or much higher MVs. These figures are for 'standard ballistics conditions' (59-deg F; sea level; 29.97 inches mercury atmospheric pressure). Colder air makes it worse; warmer/higher altitudes make it better.

If the bullet is the higher BC (0.238) longer-nose 75gn ELD-M things are a bit better, giving you an extra 100 yards before hitting each condition, but still subsonic at 1,000 with a calculated 1,061 retained fps.

How individual bullets cope with trans and subsonic speeds / transitions varies considerably. Some like the old 80gn 0.224 Sierra MK cope very well; others become increasingly unstable. Note for anybody contemplating range use of this sort of combination, sound-operated electronic targets such as the Shot-Marker need supersonic bullets at the target to work.

You also need a lot of scope elevation adjustment available. The come-up for the higher BC ELD-M is ca. 43-44 MOA at 1,000; more for the lower BC model.

Thanks Laurie, the elevation was working out at 61 MOA at 1000 yards. A great point about the transonic velocity though.

I did some ladder testing yesterday and thing I’ve almost found a sweet spot around 2,735fps…the ES isn't great (25fps) but I think it can be fettled .1 of a grain either way to improve that and that keeps me supersonic until just over 750 yards.

Regards,
Gixer

 

[gixer1]

There's only so much 223rem is going to give you with heavy bullets. What speed you after?

Not really after a speed as such, just a load that’s consistent and accurate for gong bashing out to 750-800 yards.

 

[gixer1]

This. 2560 is ridiculously slow, even if your barrel is a tad slow and only 20"long.

My 22" T3x runs a very easy 2780 with 77gr TMK, and this is not fast.

Ridiculously slow in what respect though? Running as fast as possible is not always that beneficial.

 

[secondtry]

2780 from a 22" tube is a long way below as fast as possible. If someone wants a reduced load for a specific purpose - fine - but strangling a calibre for no good reason makes no sense

Giving up potentially a safe and easy 200FPS means a much loopier trajectory - IE reduced PBR, and a similarly significant reduction in impact velocity, violence of expansion, increased wind drift etc.. 200fps will make quite a difference for any usage, but especially such things as gongs at 750 yards. Hell the vagaries of the wind at that distance are going make scoring hits hard enough without handicapping yourself by throwing away 200fps.

 

[Malxwal]

2780 from a 22" tube is a long way below as fast as possible. If someone wants a reduced load for a specific purpose - fine - but strangling a calibre for no good reason makes no sense

Giving up potentially a safe and easy 200FPS means a much loopier trajectory - IE reduced PBR, and a similarly significant reduction in impact velocity, violence of expansion, increased wind drift etc.. 200fps will make quite a difference for any usage, but especially such things as gongs at 750 yards. Hell the vagaries of the wind at that distance are going make scoring hits hard enough without handicapping yourself by throwing away 200fps.

Do your recommendations bear in mind the limitations of a factory chamber and nag length ?

 

[jthyttin]

If you're just informally bashing gongs, single loading is not a problem. Point about the chamber (throat) is good one, while many factory chambers have generous throat some do not.