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Load calculator
will270win
Member Posts: 4,845
Anyone know of a load calculator that lets you change the barrel length? Just curios to know how pressure and velocity are changed by adding barrel.
"When the pin is pulled, Mr. Grenade is not our friend."
~Secret Select Society Of Suave Stylish Smoking Jackets~
"When the pin is pulled, Mr. Grenade is not our friend."
~Secret Select Society Of Suave Stylish Smoking Jackets~
Comments
A new site I have run across, havent tried it yet.
http://ballistics.ntinnovations.com/Default.aspx
I'm not sure I understand the question; the pressure would remain the same to the extent that the bullet reached the same point in the barrel, then for the section of additional barrel the pressure would continue to drop as a function of the increased area. A program that would graph the pressure relative to position of bullet in the barrel would show what yhou're interested in- but I don't know a source of such a program.
Try above link [:D]
I'm not sure I understand the question; the pressure would remain the same to the extent that the bullet reached the same point in the barrel, then for the section of additional barrel the pressure would continue to drop as a function of the increased area. A program that would graph the pressure relative to position of bullet in the barrel would show what yhou're interested in- but I don't know a source of such a program.
I'm still learning about reloading. I read an article somewhere that explained how a longer barrel made for more FPS. The guy actually took a bolt rifle and sawed off portions of the barrel a little at a time and let all other factors remain the same. I figured that if the bullet went faster out of that longer barrel surely there is more pressure in there somewhere and I want to figure it out without cutting my barrel down like the gun rag writer did. Also, I'm shooting a 7mmBR, a pistol cartridge, in a rifle and don't want to overload it. Can ayone make any sense out of this? I took the minimum load listed and reduced it by 20% and am using that for a starting point. Haven't shot yet and likely won't until I get some good solid evidence that I ain't gonna fry my gun up all crispy like.
Thanks folks for the replies
"When the pin is pulled, Mr. Grenade is not our friend."
~Secret Select Society Of Suave Stylish Smoking Jackets~
Now I know what you mean. He was looking for the "Sweet spot" in the barrel. JustC can explain it better than I. For the most part It has to do with barrel hermonics and Velocity intersecting at the perfect length.
I just got back from the range and so far, so good. I shot 5 rounds of 7mm Benchrest with 28.0 grains of IMR 4895 through a 22 inch barrel and no signs indicating overpressure so I am going to go up from there and try to get these 120 grainers to shoot, I hope.
"When the pin is pulled, Mr. Grenade is not our friend."
~Secret Select Society Of Suave Stylish Smoking Jackets~
It's not war untill someone breaks out the .50 calibers.
A longer barrel will make more velocity as long as there is still enough expanding gasses to continually accelerate the projectile. Let's take a 30-06 loaded with say,...ohhhh H1000 and a 190gr pill. Yeah that powder isn't in most any manual becuase of it's being a magnum slow burning powder,.but with it's slow burn rate for that case capacity it will allow it to come alive in a 30" tube as it will continually remain under pressure as it get's a more compplete burn. Now,..that powder being that slow for that caliber would create a dirty burn and low velocity in a 22" barrel because once the projectile emerges the crown,..the remaining propellant is simply unburned or very inefficiently ignited. The slower the burn rate,..and the heavier the pill,..the longer burn time in the bore (albeit a minimal time increase). Tests have been done where bullets start to slow after a certain length of barrel with regards to their powder capacity. I think in one of the chapters of "Precision Shooting at 1000yds" there is a passage that lists that a 308 starts to slow in a bore greater than something like 40" +/- because as the bullet passes a certain point,..the combustion (compression) area has been increased as the bullet moves farther and farther down the bore from the case head creating a continually larger "cylinder" (think car engine). This is why we use LONG barrels for LR hunting and Benchrest shooting. The long heavy bullets and slow powders make GREAT speed out of a 30-34" tube and that increases the already high BC of those pills. More speed with long VLD pills makes more wind resistance and less elevation loss.
Barrel length (especially short barrels) has to be matched with an appropriate burn rate to get maximum efficiency. Too slow=dirt burn and too fast=inneficient use of case volume.
Then there is powder column dimensions[}:)]
Loosely speaking of course.
get a copy of "Rifle Accuracy Facts" by Harold R Vaughn and then take a refresher in Physics. It's a great read with LOTS of info on interior and exterior balistics.
Almost forgot,..there is also a formula for how much greater a barrel diameter must be for each extra inch in length. As you stretch a peice of any metal over a longer distance (especially since it is only threaded and secured on one end) the greater effect gravity has on it's strength. Therefore,..barrels have to be increased in dia as they get longer. My Light Gun barrel is just shy of 1" at the muzzle some 30" from the reciever, but my 308 finished at only 21" is only .875" and is plenty rigid. You may have noticed some bench guns having a "barrel block" clamped to the barrel just in front of the action. That block solidifies the whole rig and uniforms the barrel harminics by free-floating the action AND the barrel by using the block itself as the bedding platform. With it's huge size and 6-8" length,..it provides the rigidity at the barrel/action joint and stiffens the whole set-up for uniform and repeatable frequency from shot to shot.
why chase the game when the bullet can get em from here?....
Got Balistics?