.243 reloads with IMR 4955 results in excessive velocity

[lordpaxman]

Had anyone loaded .243 and IMR 4955 and discovered high velocities and or excessive pressures?

This thread isn't meant for "what's the best powder, bullet, primer, case etc for .243".

My other .243 reloads are all in line with existing Hodgdon reloading data, when looking at min/max velocities.

I obtained some 103 ELD X bullets, and used the online 105 AMAX load data for IMR 4955. That specifies 41.9 gr to 45.6C gr and 2723 fps to 2959 fps, 2.760 COL. (there's no data for the 103). My OCW workup had me starting at 41.0 gr, and I wanted the bullet jump to be .015" so my COL was 2.800".

The 41.0 gr (this is below minimum but .9*Max) had a 3 shot average of 2975. This is greater than the Max velocity stated. I pushed one more OCW string which in the workup is 41.9 gr which happens to be the starting charge weight and that yielded a 3 shot average of 3032.

I pulled the remaining and checked charge weights and they were all correct. I've read elsewhere that 4955 results in higher than anticipated velocities and was wondering if anyone else has seen that in .243?

 

[Jeff Flannery]

Had anyone loaded .243 and IMR 4955 and discovered high velocities and or excessive pressures?
I use 33 grains of imr 3031 in my 243's and get real good accuracy AND no signs of pressure
This thread isn't meant for "what's the best powder, bullet, primer, case etc for .243".

My other .243 reloads are all in line with existing Hodgdon reloading data, when looking at min/max velocities.

I obtained some 103 ELD X bullets, and used the online 105 AMAX load data for IMR 4955. That specifies 41.9 gr to 45.6C gr and 2723 fps to 2959 fps, 2.760 COL. (there's no data for the 103). My OCW workup had me starting at 41.0 gr, and I wanted the bullet jump to be .015" so my COL was 2.800".

The 41.0 gr (this is below minimum but .9*Max) had a 3 shot average of 2975. This is greater than the Max velocity stated. I pushed one more OCW string which in the workup is 41.9 gr which happens to be the starting charge weight and that yielded a 3 shot average of 3032.

I pulled the remaining and checked charge weights and they were all correct. I've read elsewhere that 4955 results in higher than anticipated velocities and was wondering if anyone else has seen that in .243?

 

[old heeler]

Had anyone loaded .243 and IMR 4955 and discovered high velocities and or excessive pressures?

This thread isn't meant for "what's the best powder, bullet, primer, case etc for .243".

My other .243 reloads are all in line with existing Hodgdon reloading data, when looking at min/max velocities.

I obtained some 103 ELD X bullets, and used the online 105 AMAX load data for IMR 4955. That specifies 41.9 gr to 45.6C gr and 2723 fps to 2959 fps, 2.760 COL. (there's no data for the 103). My OCW workup had me starting at 41.0 gr, and I wanted the bullet jump to be .015" so my COL was 2.800".

The 41.0 gr (this is below minimum but .9*Max) had a 3 shot average of 2975. This is greater than the Max velocity stated. I pushed one more OCW string which in the workup is 41.9 gr which happens to be the starting charge weight and that yielded a 3 shot average of 3032.

I pulled the remaining and checked charge weights and they were all correct. I've read elsewhere that 4955 results in higher than anticipated velocities and was wondering if anyone else has seen that in .243?

Your using different bullet and there is loading using same bullet 105gr V-Max different powder getting high 2900/low 3000fps. They started using IMR-4955 with 90/105gr bullets and was on par with other powders velocity. There is nothing in Hodgdon data using IMR-4955 for 243 suggesting higher velocity using IMR- 4955.

 

[lordpaxman]

Your using different bullet and there is loading using same bullet 105gr V-Max different powder getting high 2900/low 3000fps. They started using IMR-4955 with 90/105gr bullets and was on par with other powders velocity. There is nothing in Hodgdon data using IMR-4955 for 243 suggesting higher velocity using IMR- 4955.

I'm not sure what you're trying to say. I may not be clear either, but, basically a below minimum charge produced a higher than maximum velocity. That's a red flag and an indication something isn't tracking existing published load data. The 105 AMAX and 103 ELDX are close enough for load data to be used for either. I'm not looking for higher velocities using 4955.

 

[Blue68f100]

You can contact Hornady CS and they will provide load data for you.

My concern is that your OAL is putting more bullet into the brass, resulting in less volume, higher pressure. ELD's are longer than most bullets.

 

[lordpaxman]

You can contact Hornady CS and they will provide load data for you.

Argghhh….And, they said to use Hodgdon 105 AMAX data.....

My concern is that your OAL is putting more bullet into the brass, resulting in less volume, higher pressure. ELD's are longer than most bullets.

The math says differently. The ELDX is .020" longer than the AMAX, but I'm loading a COL .040" longer than the Hodgdon data. And, the AMAX load at the max is compressed.

 

[Grumulkin]

If the pressure isn't too high it DOESN'T MATTER how high the velocity is.

If the pressure is too high it DOESN'T MATTER how low the velocity is.

 

[243winxb]

Bullet difference-

0.243- 103.0 - ELD X - -1.2600" length. https://www.jbmballistics.com/ballistics/lengths/lengths.shtml#Hornady
243- 105.- A-Max®- 1.237" length.

Longer bearing surface, and thick shank of the jacket on the ELD may increase pressure and velocity?

No experence with that bullet or powder.

 

[joe-bue]

What was the barrel length of the original test rifle compared to yours?

 

[Bfh_auto]

If the pressure isn't too high it DOESN'T MATTER how high the velocity is.

If the pressure is too high it DOESN'T MATTER how low the velocity is.

This is what I think too.
My gun, brass, primers and overall length are different, so the book is a rough starting point.

 

[lordpaxman]

If the pressure isn't too high it DOESN'T MATTER how high the velocity is.

If the pressure is too high it DOESN'T MATTER how low the velocity is.

True. However, I’m a mere mortal reloader, I don’t have the means to measure pressure, I only can measure velocity. I always check for pressure signs, but I NEVER rely on the absence of them to keep me safe.

I was hoping for responses with empirical data relative to the OP. Not speculation.

 

[lordpaxman]

What was the barrel length of the original test rifle compared to yours?

The same, but you’re missing the point. For this thread, I’m only interested in anyone who has loaded 4955 in .243 within the specifications of published load data and if the velocity was in line with that data. I’m not trying to be snobby, just practical.

 

[Bandit67]

I don't own a chronograph so I have to rely on the absence of pressure signs to keep me safe.

 

[old heeler]

I'm not sure what you're trying to say. I may not be clear either, but, basically a below minimum charge produced a higher than maximum velocity. That's a red flag and an indication something isn't tracking existing published load data. The 105 AMAX and 103 ELDX are close enough for load data to be used for either. I'm not looking for higher velocities using 4955.

Your using Hodgdon data and your start load is over 200fps faster, then you read IMR-4955 was faster. If you read somewhere it was faster and your loading for Hodgdon manual, I would think you might look at other loads using that powder to see that it's not faster.