308 Win Projectile Comparisons
Posted: Sat Feb 03, 2024 9:27 am
G'day;
Over the last 3 years, we've been doing projectile comparisons for a number of different cartridges in different barrel lengths.
Attached is the 308 Winchester data we have collected.
These are all verified loads which includes a jump test.
Standard atmospherics apply;
Temp = 20°C
Pressure = 30 inHg
Humidity = 50%
DA = 660ft or 200m
Black cells indicate trans - We determine this to be the limit of the predictable flight path for bullets generally speaking. Some bullets make it through trans ok, some make it all the way to sub ok, but we have to choose a limit so for comparison purposes, we choose trans.
The wind is a 3 O'Clock, 10kph wind - for comparison, whilst drop is interesting, it's not necessarily relevant to hit probability and therefore we use wind drift as the great divider. As such, the figures in the cells next to each range and below each projectile type are drift in tenths of mils.
Some important things to note.
Your gun might attain a different muzzle velocity with the same projectile, the comparison will be the same across projectiles. Eg, if you get a faster MV out of the 155s, you'll get a faster MV (generally speaking) out of the other projectiles. The exception to this is the heavies that can't go longer (eg in the AR10 Mags) or where the throat is stopping the projectile.
All rounds were at least .75 MOA accuracy - most were .5 for an average - the SMKs short range accuracy tends to be better.
Twist rate varies across the barrels. Faster twists tends to keep the bullets stable for a longer distance. This can be seen in some of the results where in a shorter barrel may have less wind deflection or longer range than a longer barrel. We have tested down to 12.5" but this is under legal limits and was not included here.
Longer barrels with faster twists tend to deform bullets with the 6mm Creedmoor blowing up 108gr ELD-Ms at 3050fps with a 1/7 twist.
We can see concentricity issues spinning the bullets too fast, and a reduction in accuracy as the bullets jackets are stressed.
We measure each lot of projectiles, and we measure 100 rounds from each lot. There are variations between lot numbers. Berger is particularly guilty of this - so if you input this information into your BA of choice and get a different result, measure your projectiles.
We have also found that it is common for Digital tools like GRT and applied ballistic analytics'/kestrels to have different information pre-loaded in them and using the custom curves is not always the best way forward. Mil spec ammunition like the Mk248 series and M118 series are the exceptions which are generally about 98% correct with most of the variation occurring in the tips.
When assessing the projectiles we measure 100 rounds per lot, runnout is typically;
OAL;
Sierra = 8 Thou
Hornady = 3 Thou
Berger = 3 Thou
BTO;
Sierra = 2 Thou
Hornady = 3 Thou
Berger = 2 Thou
Boat Tail;
Sierra = 7 Thou
Hornady = 3 Thou
Berger = 2 Thou
We used to measure weight but there's no point as the distribution of that weight along the bullet's length is more important than the weight itself. As we don't have the tools to assess where in the bullet the weight is added/missing, and because we are unable to ascertain any discernible and repeatable results on targets for bullets that are heavier or lighter, we no longer bother.
Where the fields are white is simply where we don't have that particular projectile to test.
This information was collected by us for analytical purposes and provided to select groups/organisations.
Some of this data has previously been shared, in this forum, in part, by a member here who took it from that closed group and posted it here without permission. At the time, we felt that the nature of the post and the fact that this information was posted without our permission, was inappropriate and we asked the moderators here to take the post down, which they did. We want to say thankyou to Graeme for his support on the matter.
In retrospect, and in discussion with the rest of the team, considering the popularity of 308 in F-Class, we have decided to share the data in it's entirety.
It'll hardly blow anyone's mind to see where some projectiles stack up, given the experience in this forum, but some might find it interesting - particularly for use outside F-Class.
Over the last 3 years, we've been doing projectile comparisons for a number of different cartridges in different barrel lengths.
Attached is the 308 Winchester data we have collected.
These are all verified loads which includes a jump test.
Standard atmospherics apply;
Temp = 20°C
Pressure = 30 inHg
Humidity = 50%
DA = 660ft or 200m
Black cells indicate trans - We determine this to be the limit of the predictable flight path for bullets generally speaking. Some bullets make it through trans ok, some make it all the way to sub ok, but we have to choose a limit so for comparison purposes, we choose trans.
The wind is a 3 O'Clock, 10kph wind - for comparison, whilst drop is interesting, it's not necessarily relevant to hit probability and therefore we use wind drift as the great divider. As such, the figures in the cells next to each range and below each projectile type are drift in tenths of mils.
Some important things to note.
Your gun might attain a different muzzle velocity with the same projectile, the comparison will be the same across projectiles. Eg, if you get a faster MV out of the 155s, you'll get a faster MV (generally speaking) out of the other projectiles. The exception to this is the heavies that can't go longer (eg in the AR10 Mags) or where the throat is stopping the projectile.
All rounds were at least .75 MOA accuracy - most were .5 for an average - the SMKs short range accuracy tends to be better.
Twist rate varies across the barrels. Faster twists tends to keep the bullets stable for a longer distance. This can be seen in some of the results where in a shorter barrel may have less wind deflection or longer range than a longer barrel. We have tested down to 12.5" but this is under legal limits and was not included here.
Longer barrels with faster twists tend to deform bullets with the 6mm Creedmoor blowing up 108gr ELD-Ms at 3050fps with a 1/7 twist.
We can see concentricity issues spinning the bullets too fast, and a reduction in accuracy as the bullets jackets are stressed.
We measure each lot of projectiles, and we measure 100 rounds from each lot. There are variations between lot numbers. Berger is particularly guilty of this - so if you input this information into your BA of choice and get a different result, measure your projectiles.
We have also found that it is common for Digital tools like GRT and applied ballistic analytics'/kestrels to have different information pre-loaded in them and using the custom curves is not always the best way forward. Mil spec ammunition like the Mk248 series and M118 series are the exceptions which are generally about 98% correct with most of the variation occurring in the tips.
When assessing the projectiles we measure 100 rounds per lot, runnout is typically;
OAL;
Sierra = 8 Thou
Hornady = 3 Thou
Berger = 3 Thou
BTO;
Sierra = 2 Thou
Hornady = 3 Thou
Berger = 2 Thou
Boat Tail;
Sierra = 7 Thou
Hornady = 3 Thou
Berger = 2 Thou
We used to measure weight but there's no point as the distribution of that weight along the bullet's length is more important than the weight itself. As we don't have the tools to assess where in the bullet the weight is added/missing, and because we are unable to ascertain any discernible and repeatable results on targets for bullets that are heavier or lighter, we no longer bother.
Where the fields are white is simply where we don't have that particular projectile to test.
This information was collected by us for analytical purposes and provided to select groups/organisations.
Some of this data has previously been shared, in this forum, in part, by a member here who took it from that closed group and posted it here without permission. At the time, we felt that the nature of the post and the fact that this information was posted without our permission, was inappropriate and we asked the moderators here to take the post down, which they did. We want to say thankyou to Graeme for his support on the matter.
In retrospect, and in discussion with the rest of the team, considering the popularity of 308 in F-Class, we have decided to share the data in it's entirety.
It'll hardly blow anyone's mind to see where some projectiles stack up, given the experience in this forum, but some might find it interesting - particularly for use outside F-Class.