Is it because Hornady bullets have more bearing surface, thus increasing pressure?
Hornady bullet 60FPS faster, why?
- Thread starter Ironworker
- Start date
I do not know the answer to your question, but it is quite common in my experience for bullets of the same weight from different manufacturers to behave differently with the same powder and charges.
For example, in my 223 Rem bolt rifles, a 55 Vmax will shoot to a different POI than 55 Nosler BT with the same powder and charge weight. Perhaps due to the fact that the Vmax is flat base and the Nosler a slight boat tail. But whatever the reason, they shoot differently.
I've seen this condition in other calibers, notably the 243 Win and 308 Win.
This is why I like to use the bullet manufacturer's load date in load development whenever possible. For the most part, I found that Sierra's and Nosler's accuracy loads with some minor powder charge adjustment, often work quite well which save components and time in finding a serviceable load.
For example, in my 223 Rem bolt rifles, a 55 Vmax will shoot to a different POI than 55 Nosler BT with the same powder and charge weight. Perhaps due to the fact that the Vmax is flat base and the Nosler a slight boat tail. But whatever the reason, they shoot differently.
I've seen this condition in other calibers, notably the 243 Win and 308 Win.
This is why I like to use the bullet manufacturer's load date in load development whenever possible. For the most part, I found that Sierra's and Nosler's accuracy loads with some minor powder charge adjustment, often work quite well which save components and time in finding a serviceable load.
In my experience less bearing surface with equal bullets weights will produce less drag and if using the same powder and charge weight therefore creates more M V.
RECENT EXAMPLE : 25 X 47 LAPUA
134 GR. HORNADY ELD-M 2.126 O M 2.905 COL T/L B S .506 B C .645
38.0 GR. VV-N540 TOP 2913 FPS
135 GR. BERGER LRHT 2.131 O M 2.883 COL T/L B S .465 B C .650
38.0 GR. VV-N540 TOP 2935 FPS
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Steve Donlon
Gold $$ Contributor
I think it is more bearing surface. My new Lapua 6.5 144 gr. bullets shoot faster than my 144 gr. Berger bullets with the same load. The Lapua bullets also have more bearing surface with the ogive further forward. They also have a higher B.C. though.
I found the same thing using 6mm Sierra 107mks and then using Nosler CC 107 gr bullets. The noslers were 40 fps slower than the sierras. The reason was the nosler jacket was softer than the sierras.
ELR LVR
Silver $$ Contributor
Thats been my experience also, LESS bearing surface = More Velocity
for same bullet weight
---------
In general
Also depends on Driving band Diameter
So lets say one has less bearing surface but larger driving band , this may negate the effect.
I do know this one for a FACT;
180 gr WTC .308 Solid Projectiles have less bearing surface than many other bullets of similar weight
But give highest velocities, making a .308 equal in velocity to a 30/06
I can only attribute this to their minimal bearing surface
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Steve Donlon
Gold $$ Contributor
It makes perfect sense. Also my Lapua bullets have less jump than the Berger bullets that have less bearing surface. Lapua is .020" off and the Berger is .105" off, If that matters.
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I have those Lupua bullets, They don't weight 144grs ,143.5 is what they weight on my scale.
ELR LVR
Silver $$ Contributor
How do they shoot? And how do they compare to 142 SMK and Berger 153.5 if you have tested those others also for a comparison?
6.5 PRC 28" Bartlein Heavy Varmint bbl contour. Lupua,shot very good today, so did the Berger 144 and the Sierra 145gr TGK and also the 143gr ELDx shot well This rifle is my long range steel varmint silhouette gun.
This is the only correct answer, they did a podcast about it
Steve Donlon
Gold $$ Contributor
Did you measure the difference in muzzle velocity? I ask because I never did and just assumed they had more muzzle velocity because they are 1/2 plus less MOA at distance. But in hindsight, that could be from the difference in B.C.
Coyotefurharvester
Silver $$ Contributor
Less friction, higher velocity. Part of the friction is how the bullet expands while under pressure in the bore.
SSchnd
Silver $$ Contributor
A Tale of 3 rifles/shooters/bullets.
Fired a LR match on a warm weekend.
My 6BRAi with a SMK107 going about 2890 MV H4895 and 1/8 Kreiger 28" barrel
Buddies 6BRAi Berger 109 going about 2846 MV 1/7.5 Bartlein 5R 26" barrel. Eliseo
Both using Garmin Xero for MV
Another friend running another Eliseo in .243 and a H105 BTHP Match going about 3000 MV . unknown what chrony was used though for that datapoint. 32" barrel but I do not know twist or brand of said barrel.
The 109 Berger was still faster at the target than my SMK but we were both well faster at target than the H105 from the .243.
Wow that was enlightening. The Berger 109 carried more speed at distance.
Velocity at target on Shot Marker targets. The 109 and 107 were fired on the same target all weekend how ever the H105 was fired on another target.
I wish I still had the memory of the at target velocity differences but they were quite shocking to me.
Fired a LR match on a warm weekend.
My 6BRAi with a SMK107 going about 2890 MV H4895 and 1/8 Kreiger 28" barrel
Buddies 6BRAi Berger 109 going about 2846 MV 1/7.5 Bartlein 5R 26" barrel. Eliseo
Both using Garmin Xero for MV
Another friend running another Eliseo in .243 and a H105 BTHP Match going about 3000 MV . unknown what chrony was used though for that datapoint. 32" barrel but I do not know twist or brand of said barrel.
The 109 Berger was still faster at the target than my SMK but we were both well faster at target than the H105 from the .243.
Wow that was enlightening. The Berger 109 carried more speed at distance.
Velocity at target on Shot Marker targets. The 109 and 107 were fired on the same target all weekend how ever the H105 was fired on another target.
I wish I still had the memory of the at target velocity differences but they were quite shocking to me.
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Yes,I did
Wait !!! I thought that was only true with the 6.5 Needmore.
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