223. 75 eldm stability

[Frankm]

3000 ft elevation here, or higher, and having no problem with 9 twist. Running them around 2875-2925 fps in 223. Stable to 750…. Haven’t tried any further yet.

AB Elite ballistics program lining up nicely with projected BC.

I think elevation big factor… sea level might not be so good with a 9 twist. Best way is try it and see. I ran 105 AMax in my factory 243 with 1 - 9 1/8 twist and it worked great even though many calculators and folks said minimum of 8 twist ! Again 3000 foot or higher elevation.

 

[DLT]

3000 ft elevation here, or higher, and having no problem with 9 twist. Running them around 2875-2925 fps in 223. Stable to 750…. Haven’t tried any further yet.

AB Elite ballistics program lining up nicely with projected BC.

I think elevation big factor… sea level might not be so good with a 9 twist. Best way is try it and see. I ran 105 AMax in my factory 243 with 1 - 9 1/8 twist and it worked great even though many calculators and folks said minimum of 8 twist ! Again 3000 foot or higher elevation.

I’m at 1050’ of elevation.

 

[Frankm]

Might be a little too low/marginal. You can run a stability calculator but actually trying it still only way to know for sure…. Good Luck.

 

[DLT]

How many of you have tried the 80smk in a 8 twist 223 ? I’m at 1,100 elevation, wondering if it will stabilize enough to shoot 800

 

[Walt Krafft]

Should not be a problem. My ftr rifle likes 24.0 to 24.5 Varget or N140. 24.5 Is a little hard on the brass so work up.

 

[urbanrifleman]

People have shot about a billion of these in 8 twists.

 

[DLT]

Should not be a problem. My ftr rifle likes 24.0 to 24.5 Varget or N140. 24.5 Is a little hard on the brass so work up.

Im at 24.2 varget with the 77smk now no issues that I can see or feel with bolt lift

 

[Walt Krafft]

My standard service rifle load recommendation is 24.3 Varget stick a bullet on it, any bullet. 50 to 80 grns.

 

[Longtrain]

Thought of using the 75 ELDM in my 8 twist 223AI. Will be interesting if I can push them fast enough, definitely over 3K fps, to make up the lack of twist.

 

[urbanrifleman]

Thought of using the 75 ELDM in my 8 twist 223AI. Will be interesting if I can push them fast enough, definitely over 3K fps, to make up the lack of twist.

NEVER had heard of anyone shooting 223 in 8 twist was problem until I read these threads in the last couple of months.

 

[SSchnd]

OP that charge of varget is low as noted by the many replies, Ned laid it out best. You have to tune your load to your rifle to determine the best node/load. Chrono would be helpful in velocity confirmation but not required. Listen to the target as you work up.
1/8 works in 80 gr projectiles.
In a bolt rifle I use more powder than my gas loads in 223.
I like load testing. Make a plan before going to the range.
I also like to take my Co-ax, measure, scale and supporting items to the range to load at the club house instead of making up a series of test loads and then testing. If I do not like what a see in a few shots I can move on.
Many way to skin that load test cat, good luck .
Varget, h4895, 8208 and the VV 135/140 range powders are my choice. Not saying your powder choice is wrong in any way but to Midrange and Longrange and the heavier bullets I am more a fan of these powders.
Good luck .

 

[DLT]

NEVER had heard of anyone shooting 223 in 8 twist was problem until I read these threads in the last couple of months.

OP that charge of varget is low as noted by the many replies, Ned laid it out best. You have to tune your load to your rifle to determine the best node/load. Chrono would be helpful in velocity confirmation but not required. Listen to the target as you work up.
1/8 works in 80 gr projectiles.
In a bolt rifle I use more powder than my gas loads in 223.
I like load testing. Make a plan before going to the range.
I also like to take my Co-ax, measure, scale and supporting items to the range to load at the club house instead of making up a series of test loads and then testing. If I do not like what a see in a few shots I can move on.
Many way to skin that load test cat, good luck .
Varget, h4895, 8208 and the VV 135/140 range powders are my choice. Not saying your powder choice is wrong in any way but to Midrange and Longrange and the heavier bullets I am more a fan of these powders.
Good luck .

I know now it is low. My chrono of choice at the time was a magnetospeed which I feel is plenty accurate but I didn’t think of it at the time causing impact shifts which it does. Some say they have seen it and others say it don’t affect their barrels. Mine it does so instead of shooting double the components watching for poi and grouping and trying to get chrono data with it attached I have went without it. I do wish I had went a different route with that choice. My barrel has not shown any promise with the 75 eldm yet

 

[RegionRat]

How many of you have tried the 80smk in a 8 twist 223 ? I’m at 1,100 elevation, wondering if it will stabilize enough to shoot 800

Yes, the SMK 80 is older than the Hornady ELD models and has been very popular with the XTC and Mid Range crowds for decades.

The pressure I used is high (lower altitude) and you would have and SG that rounds to 1.5


Before anyone asks, here is the SMK 77 at 8 twist


And the 77 TMK at 8 twist


If your bullet length is listed in the Litz book or in the JBM library, you can learn to get a Miller Equation answer without an engineering degree.

Just keep in mind, the Miller equation is not exact so the closer you let the SG get to 1 the higher the chances you can find yourself unstable.

There are several reasons and examples of an SG being close to 1 where folks have stability, and also examples where they were higher and didn't.

 

[Chilly807]

I'm trying the 80 SMK in the same 223 Tikka (1 in 8 twist) that didn't shoot well with the 75 ELD-M bullets. Groups are better, but I haven't tried it at 800m yet. With 23.8 gr of N140 in a 24" barrel I'm getting about 2740 at the muzzle, no signs of pressure.

The Tikka has a SAAMI chamber and a short throat, so getting much more powder in the case without compressing the load is going to be problematic.

I'm already using a drop tube, so I might get to 24.0-24.3 without any crunches but that's about it.
The rifle shoots well at 2700-2750, so as long as the bullets stay supersonic at 800m that's enough for me. The Lapua app predicts 1260-1280 fps at the target.

Using the Berger stability calculator, the 80 SMK in an 8-twist barrel at 2750 fps comes in at 1.45 SG, which is close enough to the 1.5 benchmark for my use.
My elevation is closer to sea level than many of you, probably 200-300 ft.

 

[DLT]

I'm trying the 80 SMK in the same 223 Tikka (1 in 8 twist) that didn't shoot well with the 75 ELD-M bullets. Groups are better, but I haven't tried it at 800m yet. With 23.8 gr of N140 in a 24" barrel I'm getting about 2740 at the muzzle, no signs of pressure.

The Tikka has a SAAMI chamber and a short throat, so getting much more powder in the case without compressing the load is going to be problematic.

I'm already using a drop tube, so I might get to 24.0-24.3 without any crunches but that's about it.
The rifle shoots well at 2700-2750, so as long as the bullets stay supersonic at 800m that's enough for me. The Lapua app predicts 1260-1280 fps at the target.

Using the Berger stability calculator, the 80 SMK in an 8-twist barrel at 2750 fps comes in at 1.45 SG, which is close enough to the 1.5 benchmark for my use.
My elevation is closer to sea level than many of you, probably 200-300 ft.

Thanks for all that information. Mine is throated just a bit but I don’t have a drop tube

 

[Chilly807]

Thanks for all that information. Mine is throated just a bit but I don’t have a drop tube

I started using one several months ago. With small cases like the 223 Rem they give you a bit more room for powder.
Mine is just an 8" length of 1/4" stainless tubing with one end necked down to fit into the case mouth and the other end chamfered so powder flows smoothly through it.

 

[DLT]

Was

I started using one several months ago. With small cases like the 223 Rem they give you a bit more room for powder.
Mine is just an 8" length of 1/4" stainless tubing with one end necked down to fit into the case mouth and the other end chamfered so powder flows smoothly through it.

makes that much difference in capacity ? I have read on them but never did any hard investigation

 

[RegionRat]

At sea level in standard conditions, you have to be a little above 2750 fps muzzle to keep the SMK 80 above sonic at 1000 yards to use e-targets that need the shock wave.

 

[memilanuk]

Was

makes that much difference in capacity ? I have read on them but never did any hard investigation

They can.

Another trick, if you're really struggling to fit enough powder in the case, is to sit all the charged cases in a loading block / tray, with bullets sitting in the case mouths, and hold it up against the drum of a vibratory tumbler. You know how cereal settles in the box during shipping? Same thing here. You'd be surprised how much room you can gain.

 

[Chilly807]

At sea level in standard conditions, you have to be a little above 2750 fps muzzle to keep the SMK 80 above sonic at 1000 yards to use e-targets that need the shock wave.

That would be about right, maybe a bit faster even to have a comfortable margin.
With any "built" rifle having a 28-30" barrel, getting close to 3000 fps with an 80 SMK shouldn't be too hard.
My Tikka has 2 built-in handicaps for an entry level F-TR rifle, first being the relatively short 24" 8-twist barrel and second is the standard SAAMI chamber with short throat.
I call them handicaps, but it's a rifle that was meant to blow up varmints at 300-500 yds, not lob target bullets accurately at 800-1000 yds.