Bullet penetration?
01-26-2010, 09:05 AM
#12
Giant Nontypical
Join Date: Nov 2005
Posts: 6,585
The diameter as well as the weight enters into it so does the construction of the bullet.
Diameter to weight ratio is call sectional density you will find that by looking for it you can find the SD or sectional density listed with the BC often.
You will also find that the 200gr 40 caliber bullets with compare to the 300gr 45 caliber bullets and that the same construction bullet like two Shock Waves should given exactly the same circumstances will give much the same penetration.
Where one of the differences comes in is that you can push a 40 cal. 200 gr. quite a bit faster with a max load.
An other thing you must take into consideration is that some bullets have a speed limit faster than you can push them. Many years a go I used to use PB and since the 245 had a much better trajectory I tried to make it work for me but when you push it fast enough to get it to shoot flat enough it disintegrated or fragmented on impact so I had to modify the bullet to get good performance out of it. what I did was plug the hollow point with lead for deer and a brass plug for bear and elk so that it would penetrate and mushroom in the proper relationship.
A comparison of a pointed full metal jacket bullet and a hollow point can show you that difference. A happy medium or compromise is necessary most of the time, there is more than one school of thought and more than one need for deer a hollow point that does not break up but usually has enough penetration to get out the other side is what I consider ideal for deer. But I would not be likely to use the same bullet for buffalo. To give an example a 250 gr Gold Dot hollow point is a very good bullet for whitetail deer but to get just the right combination I do not use more than 110 gr load of BH where as if I were going buffalo hunting I would use a 275 or 300 gr Lehigh with 140 gr of BH. The Lehigh is in a category by itself it open explosively then gets max penetration in the form of a wad cutter which pushes a considerable shock wave in front of it [I used one on my buck this year on a long angle running shot went in next to the left ham and was sticking out in the skin after breaking the right front shoulder] he was running pretty fast and only got 25 yds about half of which he skidded on his side. There are many things to consider when it comes to bullet construction and shape. There is no such thing as one bullet being good for every thing, the bullet needed for elephant is the opposite needed for varmints and most other game falls in between. Lee
Diameter to weight ratio is call sectional density you will find that by looking for it you can find the SD or sectional density listed with the BC often.
You will also find that the 200gr 40 caliber bullets with compare to the 300gr 45 caliber bullets and that the same construction bullet like two Shock Waves should given exactly the same circumstances will give much the same penetration.
Where one of the differences comes in is that you can push a 40 cal. 200 gr. quite a bit faster with a max load.
An other thing you must take into consideration is that some bullets have a speed limit faster than you can push them. Many years a go I used to use PB and since the 245 had a much better trajectory I tried to make it work for me but when you push it fast enough to get it to shoot flat enough it disintegrated or fragmented on impact so I had to modify the bullet to get good performance out of it. what I did was plug the hollow point with lead for deer and a brass plug for bear and elk so that it would penetrate and mushroom in the proper relationship.
A comparison of a pointed full metal jacket bullet and a hollow point can show you that difference. A happy medium or compromise is necessary most of the time, there is more than one school of thought and more than one need for deer a hollow point that does not break up but usually has enough penetration to get out the other side is what I consider ideal for deer. But I would not be likely to use the same bullet for buffalo. To give an example a 250 gr Gold Dot hollow point is a very good bullet for whitetail deer but to get just the right combination I do not use more than 110 gr load of BH where as if I were going buffalo hunting I would use a 275 or 300 gr Lehigh with 140 gr of BH. The Lehigh is in a category by itself it open explosively then gets max penetration in the form of a wad cutter which pushes a considerable shock wave in front of it [I used one on my buck this year on a long angle running shot went in next to the left ham and was sticking out in the skin after breaking the right front shoulder] he was running pretty fast and only got 25 yds about half of which he skidded on his side. There are many things to consider when it comes to bullet construction and shape. There is no such thing as one bullet being good for every thing, the bullet needed for elephant is the opposite needed for varmints and most other game falls in between. Lee
01-26-2010, 09:46 AM
#13
Giant Nontypical
Join Date: Nov 2004
Posts: 5,425
Let's get a little deeper...
Ballistic Coefficient has to do with how streamlined a bullet is...A bullet with a higher BC will fly flatter than one with a lower BC if they both leave the barrel at the same speed...
Sectional Density has to do with how well two bullets that are constructed the same will penetrate if they hit the target at the same speed...
I've been playing around with the Hornady Ballistic Calculator for a few days, here are some figures for different bullets...
250SST/Shockwave...Launched with 150grs of powder, which gives it a higher BC and I already know over 90grs the groups open up in my rifle...BC .210 SC .175...
300gr .452 XTP... BC .180 SC .210
250gr .452 XTP... BC .146 SC .175
300gr .429 XTP...BC .245 SC .232
240gr .429 XTP...BC .205 SC .185
Of these the .429 300gr has the highest BC and the highest SC...
One reason I tried the SSTs is they flew flatter at 150 yards than either the 295 PowerBelt and the .300gr Barnes MZ in my Knight Disc with a 22 inch barrel...
Like many I found the SST didn't mushroom well because of the sharper tip design...A hollow point travelling at the same speed should mushroom better than the sharper tip designs...I went to high shoulder shots to help this bullet open up and had bang flops on my kills...A buddy that was using them found that on broadside lung shots the deer were running 100yards and the exit wound was about the same size as the entrance...
The guy that developed the Savage smokeless design lives up in Greensboro and posts on the NC Hunting Site...He loves the .452 300gr XTP in his guns, but he is pushing them at 2200fps...My Knight using Pyrodex or Goex is probably pushing a 300gr closer to 1500-1550fpr...I'm suspectiong that he can't use the .429s with the green sabot because the thicker sabot won't handle the pressures that he is shooting...
What I'm wanting to have is a bullet that I can sight in 2 1/2 - 3 inches high at 100 yards and be no more than 4-5 inches low at 150...
I'm hoping the .429 300gr XTP will do this, if it doesn't group well in my rifle then I'm going to try the .429 240gr XTP...
I've already tried both the .452 300gr and the .452 .250gr in my Knight and neither grouped well...I have high expectations for the .429 300gr XTP because it's a longer bullet than the .452 300gr as is the 300gr MZ...My Knight loves that 300gr MZ and if neither .429 bullet groups well I'll either go back to that or continue to use the 250SSTs...
Ballistic Coefficient has to do with how streamlined a bullet is...A bullet with a higher BC will fly flatter than one with a lower BC if they both leave the barrel at the same speed...
Sectional Density has to do with how well two bullets that are constructed the same will penetrate if they hit the target at the same speed...
I've been playing around with the Hornady Ballistic Calculator for a few days, here are some figures for different bullets...
250SST/Shockwave...Launched with 150grs of powder, which gives it a higher BC and I already know over 90grs the groups open up in my rifle...BC .210 SC .175...
300gr .452 XTP... BC .180 SC .210
250gr .452 XTP... BC .146 SC .175
300gr .429 XTP...BC .245 SC .232
240gr .429 XTP...BC .205 SC .185
Of these the .429 300gr has the highest BC and the highest SC...
One reason I tried the SSTs is they flew flatter at 150 yards than either the 295 PowerBelt and the .300gr Barnes MZ in my Knight Disc with a 22 inch barrel...
Like many I found the SST didn't mushroom well because of the sharper tip design...A hollow point travelling at the same speed should mushroom better than the sharper tip designs...I went to high shoulder shots to help this bullet open up and had bang flops on my kills...A buddy that was using them found that on broadside lung shots the deer were running 100yards and the exit wound was about the same size as the entrance...
The guy that developed the Savage smokeless design lives up in Greensboro and posts on the NC Hunting Site...He loves the .452 300gr XTP in his guns, but he is pushing them at 2200fps...My Knight using Pyrodex or Goex is probably pushing a 300gr closer to 1500-1550fpr...I'm suspectiong that he can't use the .429s with the green sabot because the thicker sabot won't handle the pressures that he is shooting...
What I'm wanting to have is a bullet that I can sight in 2 1/2 - 3 inches high at 100 yards and be no more than 4-5 inches low at 150...
I'm hoping the .429 300gr XTP will do this, if it doesn't group well in my rifle then I'm going to try the .429 240gr XTP...
I've already tried both the .452 300gr and the .452 .250gr in my Knight and neither grouped well...I have high expectations for the .429 300gr XTP because it's a longer bullet than the .452 300gr as is the 300gr MZ...My Knight loves that 300gr MZ and if neither .429 bullet groups well I'll either go back to that or continue to use the 250SSTs...
Last edited by nchawkeye; 01-26-2010 at 09:49 AM.
