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New Creedmoor load test
- Thread starter kilotanker22
- Start date
Looks like you have 3 groups there.
Even with the 7mm Rem Mag, most of my bullets go subsonic at 1,500 yards.
Exception would be if you could get a 195gr Berger to go 2,800 fps. At my conditions it goes subsonic at 1,700 yards.
Personally, i'd shoot your distance and see what happens. See how the bullet actually reacts to going subsonic.
Even with the 7mm Rem Mag, most of my bullets go subsonic at 1,500 yards.
Exception would be if you could get a 195gr Berger to go 2,800 fps. At my conditions it goes subsonic at 1,700 yards.
Personally, i'd shoot your distance and see what happens. See how the bullet actually reacts to going subsonic.
kilotanker22
New member
Yeah, I am going to re shoot that group today. I also bought some StaBall 6.5 to try out.
Bryan Litz's book, Ballistic Performance of Rifle Bullets lists measured BC's to use. Manufacturer G1 box numbers are often given at the high end of the velocity range they expect the bullet to be used at for competitive selling point reasons. These numbers work OK to 300 yards or so, but will mess up with long-range calculations. For the 147-grain ELD from Below 3000 to below 1500 fps, the measured G1 BC drops by 16%. The G7 BC only drops about 6% in that range and would be better to use.
However, you don't have to rely on a BC model to approximate Hornady bullet performance anymore as the Hornady 4 DOF calculator is linked to a list of actual Doppler RADAR-measured individual drag functions for its bullets. In very long-range shooting, where BC errors accumulate by the time the bullet gets to the target, this will always be the more accurate way to go, try the advanced calculator.
I ran it for your altitude (average barometric pressure 28.70 in-Hg at 1200 feet) in 80°F and with 50% RH, where Mach 1 works out to 1,142.5 fps according to this calculator. (Humidity thins air density, but is not a huge influence; going to 78% RH raises Mach 1 to 144.3 fps). What the Hornady calculator shows is the bullet needs to start out with a muzzle velocity of 3155 fps to fall just to that speed of sound at 1760 yards.
I looked further to see what would happen with range calculations from BC's to see how far off they could get, and the answer is, a lot. For each BC type (single G1, single G7, multiple breakpoint G1 and G7 tables) and for the single BC numbers I got disagreements of over 200 ft/s between various ballistics calculators. The reasons are cumulative iteration and rounding errors and conversion precision errors between native metric and native inch calculators. When I went from the BC on the box through the measured G1 and G7 average BC's as well as the multiple BC's broken up by velocity ranges, the result showed required muzzle velocities from 2756 fps to 3064 fps to stay above the speed of sound to 1760 yards. All were slower than the actual drag function says is required because what is actually required is greater for an important reason:
As you probably know, drag coefficients rise sharply at the speed of sound and change a lot with relatively small changes in shape. This matters because it means BC-based calculations can be easily befuddled in what is called the transonic velocity range. Why? Well, bullets have curves and angles on their surfaces and the air flows over them all at once. When the bullet is going at exactly Mach 1, the shockwave formation drops off, but air flowing over the ogive has a greater distance to travel than air along the sides does with the same amount of distance covered, so there is some supersonic airflow over the ogive at Mach 1. The tail also should have that, but laminar separation can occur, and at what velocity and bullet diameter that occurs depends on the angle of the boattail. The net result is there is changing drag messing with the bullet starting between about Mach 1.2 and 1.25, depending on the bullet profile. It doesn't stop completely until below about Mach 0.75 and 0.85, again, depending on the bullet profile. So the transonic range can be considered anything from Mach 0.85-1.2 to Mach 0.75-1.25, and some bullets can get jiggy in that range. So, if you want the best ballistic performance, you really would prefer to keep the bullet from falling into that transonic range, though some will get through it a lot better than others.
Quite a mess, isn't it? Bottom line, I think you'll probably like the .338.
However, you don't have to rely on a BC model to approximate Hornady bullet performance anymore as the Hornady 4 DOF calculator is linked to a list of actual Doppler RADAR-measured individual drag functions for its bullets. In very long-range shooting, where BC errors accumulate by the time the bullet gets to the target, this will always be the more accurate way to go, try the advanced calculator.
I ran it for your altitude (average barometric pressure 28.70 in-Hg at 1200 feet) in 80°F and with 50% RH, where Mach 1 works out to 1,142.5 fps according to this calculator. (Humidity thins air density, but is not a huge influence; going to 78% RH raises Mach 1 to 144.3 fps). What the Hornady calculator shows is the bullet needs to start out with a muzzle velocity of 3155 fps to fall just to that speed of sound at 1760 yards.
I looked further to see what would happen with range calculations from BC's to see how far off they could get, and the answer is, a lot. For each BC type (single G1, single G7, multiple breakpoint G1 and G7 tables) and for the single BC numbers I got disagreements of over 200 ft/s between various ballistics calculators. The reasons are cumulative iteration and rounding errors and conversion precision errors between native metric and native inch calculators. When I went from the BC on the box through the measured G1 and G7 average BC's as well as the multiple BC's broken up by velocity ranges, the result showed required muzzle velocities from 2756 fps to 3064 fps to stay above the speed of sound to 1760 yards. All were slower than the actual drag function says is required because what is actually required is greater for an important reason:
As you probably know, drag coefficients rise sharply at the speed of sound and change a lot with relatively small changes in shape. This matters because it means BC-based calculations can be easily befuddled in what is called the transonic velocity range. Why? Well, bullets have curves and angles on their surfaces and the air flows over them all at once. When the bullet is going at exactly Mach 1, the shockwave formation drops off, but air flowing over the ogive has a greater distance to travel than air along the sides does with the same amount of distance covered, so there is some supersonic airflow over the ogive at Mach 1. The tail also should have that, but laminar separation can occur, and at what velocity and bullet diameter that occurs depends on the angle of the boattail. The net result is there is changing drag messing with the bullet starting between about Mach 1.2 and 1.25, depending on the bullet profile. It doesn't stop completely until below about Mach 0.75 and 0.85, again, depending on the bullet profile. So the transonic range can be considered anything from Mach 0.85-1.2 to Mach 0.75-1.25, and some bullets can get jiggy in that range. So, if you want the best ballistic performance, you really would prefer to keep the bullet from falling into that transonic range, though some will get through it a lot better than others.
Quite a mess, isn't it? Bottom line, I think you'll probably like the .338.
kilotanker22
New member
CAUTION: The following post includes loading data not covered by currently published sources of tested data for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assumes any liability for any damage or injury resulting from the use of this information.
Thank you for breaking it out in that Fashion Unclenick. Basically things that I I understand in a limited way. I ha e been really thinking hard on that .338 Lapua my friend has. Or buying a Savage 110 Elite Precision in 338 Lapua. I plan to top it with a Leupold Mark 5 HD. I am thinking buying the Elite Precision, because of the 30 inch barrel, over my friends HS Precision with a 26 inch barrel. The sole purpose of that rifle would be getti g to a mile super sonic.
On another note, I bought some StaBall 6.5 to try and I jumped right to Hodgdon's max load since I figured I would be there anyway. And the trend of this rifle's max load being slightly higher than Hodgdon's data across the board.
At their maximum listed charge of 43.3 grains, My average velocity was only 2661 with an ES of 36 fps There were no pressure signs at all.
Tonight I am going to load 43.5, 44 and 44.5 grains and see where that gets me.
I would like to at least be able to push these bullets as fast as I can with H-4350. Hopefully with a velocity spread similar to H-4350. I am looking for ES less than 20 fps across a ten shot string. It's easy to do with H-4350, I just think that the pressure needs to rise a little for this StaBall to burn More efficiently.
Thank you for breaking it out in that Fashion Unclenick. Basically things that I I understand in a limited way. I ha e been really thinking hard on that .338 Lapua my friend has. Or buying a Savage 110 Elite Precision in 338 Lapua. I plan to top it with a Leupold Mark 5 HD. I am thinking buying the Elite Precision, because of the 30 inch barrel, over my friends HS Precision with a 26 inch barrel. The sole purpose of that rifle would be getti g to a mile super sonic.
On another note, I bought some StaBall 6.5 to try and I jumped right to Hodgdon's max load since I figured I would be there anyway. And the trend of this rifle's max load being slightly higher than Hodgdon's data across the board.
At their maximum listed charge of 43.3 grains, My average velocity was only 2661 with an ES of 36 fps There were no pressure signs at all.
Tonight I am going to load 43.5, 44 and 44.5 grains and see where that gets me.
I would like to at least be able to push these bullets as fast as I can with H-4350. Hopefully with a velocity spread similar to H-4350. I am looking for ES less than 20 fps across a ten shot string. It's easy to do with H-4350, I just think that the pressure needs to rise a little for this StaBall to burn More efficiently.
kilotanker22
New member
Thanks Unclenick
kilotanker22
New member
CAUTION: The following post includes loading data not covered by currently published sources of tested data for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assumes any liability for any damage or injury resulting from the use of this information.
Well 44 grains of StaBall 6.5 got me up to 2710 fps. ES and SD were better though. Group size was sub MOA, but kind of danced around in a circular pattern. I can load this hotter, but H-4350 is still 50 fps faster and I use.more than 2 grains less powder to do so.
Retested the 140 Matchking in the new brass with H-4350 load. Velocity was a little low, but still shoots groups you could cover with a dime.
Well 44 grains of StaBall 6.5 got me up to 2710 fps. ES and SD were better though. Group size was sub MOA, but kind of danced around in a circular pattern. I can load this hotter, but H-4350 is still 50 fps faster and I use.more than 2 grains less powder to do so.
Retested the 140 Matchking in the new brass with H-4350 load. Velocity was a little low, but still shoots groups you could cover with a dime.
kilotanker22
New member
I did notice that I had to reduce my powder charge significantly with this Peterson Brass. A full 1.2 grains less powder, but only lost like 45 fps.
kilotanker22
New member
Again today, no better than .9 MOA ten shot groups shot three such groups. .9, 1 and 1 MOA ten shot groups. That was with the 147 Grain ELD Match bullet and a Hodgdon's max charge of H-4350.
I am nearly certain that this bullet will need to move closer to the lands to improve the groups. Problem is that they are at mag length and still .075" off the lands.
I think that I am going to start load workup over again. I AM GONNA DROP to 39 grains of H-4350 and start these bullets at the lands. Work up in half grain increments to find my max charge at the lands.
I am also gonna order some MDT magazines without the binder plate. That will allow me to load out to 2.960". These bullets at the lands are 2.920". Once I find my maximum charge I will do a seating depth test. Although I am not sure it's worth a complete load workup. I only have around 500-700 shots left on this barrel.
I am nearly certain that this bullet will need to move closer to the lands to improve the groups. Problem is that they are at mag length and still .075" off the lands.
I think that I am going to start load workup over again. I AM GONNA DROP to 39 grains of H-4350 and start these bullets at the lands. Work up in half grain increments to find my max charge at the lands.
I am also gonna order some MDT magazines without the binder plate. That will allow me to load out to 2.960". These bullets at the lands are 2.920". Once I find my maximum charge I will do a seating depth test. Although I am not sure it's worth a complete load workup. I only have around 500-700 shots left on this barrel.
kilotanker22,
I don't know how many rounds you have down that tube but you might be underestimating the life left in that barrel.
I have two 6.5mm Savages in 6.5mm CM - 12 LRP and 12 FV - with over 4,250 and 2,850 rounds down range respectively and they shoot as good or better than they did with 200 rounds down range.
Unless you have more than that down your barrel, you may have many more rounds of life left.
I keep shooting until I can measure a difference in average group size over a significant sample.
I only had one barrel in another rifle, a .308, start to lose accuracy due to wear, and that was because it started out with a chamber that was 0.080 deeper than SAAMI recommended O.A.L. and by the time the rifling eroded an additional 0.090 I couldn't seat the bullets out any longer and still maintain neck tension.
I don't know how many rounds you have down that tube but you might be underestimating the life left in that barrel.
I have two 6.5mm Savages in 6.5mm CM - 12 LRP and 12 FV - with over 4,250 and 2,850 rounds down range respectively and they shoot as good or better than they did with 200 rounds down range.
Unless you have more than that down your barrel, you may have many more rounds of life left.
I keep shooting until I can measure a difference in average group size over a significant sample.
I only had one barrel in another rifle, a .308, start to lose accuracy due to wear, and that was because it started out with a chamber that was 0.080 deeper than SAAMI recommended O.A.L. and by the time the rifling eroded an additional 0.090 I couldn't seat the bullets out any longer and still maintain neck tension.
kilotanker22
New member
I have about 1300 rounds down the tube after today. I am pretty sure my main issue is that this bullet needs to be closer to the lands.
kilotanker22
New member
I have not, H-4350 shoots so well with excellent velocity spreads. Everything else shoots really well except for this bullet. I mean 1 MOA ten shot groups are ok, but I know the rifle is capable of a third that size.
I will load these long and single feed them for now to see if they will shoot like every other bullet I have tried. Once I have those MDT magazines I will be able to load them at the lands.
I think I might start at 40 grains of H-4350 instead of 39. Starting the bullet close to the lands will raise pressure, but also moving that bullet .065" further out of the case will increase case capacity a little.
I will need to load 20 rounds at each increment. 10 for velocity testing and ten for group size. If I get lucky and one of the increments shoots the way I want it to then I am done. If not then I will choose the one with the best velocity spread and do a seating depth test. Also right now I am at the lower end of my barrel time node. Hopefully lowering the charge weight and moving the bullet closer to the lands will decrease barrel time and get me more towards the middle of that node.
I will load these long and single feed them for now to see if they will shoot like every other bullet I have tried. Once I have those MDT magazines I will be able to load them at the lands.
I think I might start at 40 grains of H-4350 instead of 39. Starting the bullet close to the lands will raise pressure, but also moving that bullet .065" further out of the case will increase case capacity a little.
I will need to load 20 rounds at each increment. 10 for velocity testing and ten for group size. If I get lucky and one of the increments shoots the way I want it to then I am done. If not then I will choose the one with the best velocity spread and do a seating depth test. Also right now I am at the lower end of my barrel time node. Hopefully lowering the charge weight and moving the bullet closer to the lands will decrease barrel time and get me more towards the middle of that node.
Kilotanker22,
I don't know how close to the lands you intend to go, but if you start in full contact with the lands, lowering the charge about 10% will keep the pressure close to the same as when you have your bigger jump.
Regarding shot-out barrels, I think most people expect them to just gradually shoot larger and larger groups. That can happen with uniform throat errosion, but when a barrel really starts to die, it is usually because the throat is becoming non-uniform due to chips breaking off the alligator skin thermal stress cracking pattern that eventually forms. When that occurs, the uneven throat can tilt some bullets more than others, so you start to get fliers.
When I shot out my first M1A barrel, I had shot a dozen rounds clean onto a slow-fire target and suddenly got an uncalled 9 at about 10:30. I figured it was me, but within another twenty rounds, I had another in the same place. Over the course of the summer it went from one-in-twenty to one-in-ten and then one-in-five, at which point it finally dawned on me that the problem wasn't me and I needed a new barrel.
In an article on barrel life in Precision Shooting magazine in the late '90s, Sierra's range was used to shoot out .308 Win barrels made of chrome-moly and stainless, some cryo-treated, some not, some using moly bullets and some not, but the criteria for life was the same: the appearance of the first flier.
G. David Tubb says his throat conditioning abrasive bullets can recover throat uniformity and double the life of a barrel, thereby (though the throat will be longer). I haven't tried this form of firelapping yet.
I don't know how close to the lands you intend to go, but if you start in full contact with the lands, lowering the charge about 10% will keep the pressure close to the same as when you have your bigger jump.
Regarding shot-out barrels, I think most people expect them to just gradually shoot larger and larger groups. That can happen with uniform throat errosion, but when a barrel really starts to die, it is usually because the throat is becoming non-uniform due to chips breaking off the alligator skin thermal stress cracking pattern that eventually forms. When that occurs, the uneven throat can tilt some bullets more than others, so you start to get fliers.
When I shot out my first M1A barrel, I had shot a dozen rounds clean onto a slow-fire target and suddenly got an uncalled 9 at about 10:30. I figured it was me, but within another twenty rounds, I had another in the same place. Over the course of the summer it went from one-in-twenty to one-in-ten and then one-in-five, at which point it finally dawned on me that the problem wasn't me and I needed a new barrel.
In an article on barrel life in Precision Shooting magazine in the late '90s, Sierra's range was used to shoot out .308 Win barrels made of chrome-moly and stainless, some cryo-treated, some not, some using moly bullets and some not, but the criteria for life was the same: the appearance of the first flier.
G. David Tubb says his throat conditioning abrasive bullets can recover throat uniformity and double the life of a barrel, thereby (though the throat will be longer). I haven't tried this form of firelapping yet.
G. David Tubb says his throat conditioning abrasive bullets can recover throat uniformity and double the life of a barrel, thereby (though the throat will be longer). I haven't tried this form of firelapping yet.
I like them for barrel break in but have never tried them on recovery. I have a .260 barrel that has over 2K down it and starting to throw flyers that I will try them on either next month or September. I will remeasure the lands, and do an adjust on base to ogive, clean, shoot 15 rounds then 15 of the Tubbs, clean, and then 15 more. See if flyers are reduced
That is if I remember, I am in the middle of relocating and have to setup a reloading room and find some range time first.
kilotanker22
New member
So far I have observed around .010" of erosion. That is only based on CBTO to the lands in this rifle using the same Hornady bullet I first started with.
That may slow a little now the corners are rounded. Note, too, you will often get different readings from tangent and secant ogive bullets because the former tend to touch the lands at bore diameter first, while the latter tend to touch them at groove diameter first. This is thought to be part of the reason secant ogives can be fussier about cartridge runout.
kilotanker22
New member
Unclenick, that is precisely why I have used the same bullet to track throat erosion. I do see what you speak of though. A Sierra 140 grain Matchkings CBTO at the lands is using the Hornady tool is 2.288". Where the Hornady 140 grain ELD Match bullet measures 2.272". The 147 grain ELD Match bullet's CBTO is 2.272" as well.