.300 win mag barrel length and twist...

[ncwg2boatguy]

Never seen a 1-12 twist .30? Not disagreeing, just obviously not alot out there I assume.

 

[Docx]

You're only wrong on all counts here. As I said "slight nose up angle" and many of us here have and do hunt at ranges where the bullets are going transonic or subsonic.

An unstable bullet or marginally stable bullet will never be as accurate as a stable bullet the physics simply won't allow for it. It is when they become marginally stable that significant yaw develops which then has a negative impact on accuracy.

Guess I'm wrong then
Cheers
BTW slightly nose up compared to what?

 

[coyotezapper]

You're only wrong on all counts here. As I said "slight nose up angle" and many of us here have and do hunt at ranges where the bullets are going transonic or subsonic.

An unstable bullet or marginally stable bullet will never be as accurate as a stable bullet the physics simply won't allow for it. It is when they become marginally stable that significant yaw develops which then has a negative impact on accuracy.

I'm curious about something you said here. What bullet are you using that will open up and perform properly on game at transonic or subsonic ranges?

 

[WildRose]

I'm curious about something you said here. What bullet are you using that will open up and perform properly on game at transonic or subsonic ranges?

The Peregrine's don't seem to be affected much if any by velocity due to the engineering in the nose. Expansion is caused by essentially a shape charge created by the pressure on impact rather than simply the force of the tip being driven back against the meplat.

The "plunger" has a double angle on it similar to an upside down bowling ball target and an air pocket between the base of the stem and the bottom of the drill hole. As the tip is driven back a massive amout of pressure is created in that airspace as it is compressed.

Exit wounds dont' seem to differ much even with extreme variations in speed on impact and the few I have recovered on the long shots are still showing about 1.5x caliber or slightly better expansion.

I've shot a few of the VLR5's in 6.5, 7mm, and .30 cal out to transonic or subsonic ranges and been real impressed with the consistency.

 

[WildRose]

Guess I'm wrong then
Cheers
BTW slightly nose up compared to what?

Compared to zero or a negative angle on the nose.

 

[Hookdown]

I guess I dont understand all the heavy bullet craze if you say are running a 300 Win. Mag at 2950 with the 215 and you say step up to the 230 and your muzzle velocity drops to 2875 you dont gain anything, so to me if you dont keep up your MV it's a wash. I guess it you just like to experiment then so be it.
I guess my thinking is if it ain't broke dont fix it.
Now something like a 300 norma is a different story.

You absolutely DO gain something, and its a lot. First of all, usually as bullet weight increases in the same caliber and bullet type, so does Ballistic Coefficient. Pushed to equal pressures, the higher weight/ BC bullet will always have more energy. And that disparity will only increase with range. At greater distances, the difference in energy states can be significant. But it is also true that at shorter distances, that difference can be irrelevant.

But to me, the following is the main reason to use the highest BC bullets you can, and the concept I think you're overlooking. WIND. If your rifle/ ammo combination is accurate and consistent, and your target distance is known, dialing in the proper elevation to effect a proper impact VERTICALLY becomes fairly straight forward. But the big spoiler and often limiting factor for us mere mortals is HORIZONTAL deflection, i.e. the wind call. It is always a guess. Some are better at it than others. But I think most LR hunters would agree that the wind is very often the criteria that limits the range they are willing to shoot. The higher the bullet's BC, the more error you can have in your wind call and still be successful. That is science. That is fact. And that benefit ALWAYS matters at any range. And at even a few hundred yards, with a strong wind, the drift difference between higher and lower BC bullets is dramatic.

 

[Bravo 4]

You absolutely DO gain something, and its a lot. First of all, usually as bullet weight increases in the same caliber and bullet type, so does Ballistic Coefficient. Pushed to equal pressures, the higher weight/ BC bullet will always have more energy. And that disparity will only increase with range. At greater distances, the difference in energy states can be significant. But it is also true that at shorter distances, that difference can be irrelevant.

But to me, the following is the main reason to use the highest BC bullets you can, and the concept I think you're overlooking. WIND. If your rifle/ ammo combination is accurate and consistent, and your target distance is known, dialing in the proper elevation to effect a proper impact VERTICALLY becomes fairly straight forward. But the big spoiler and often limiting factor for us mere mortals is HORIZONTAL deflection, i.e. the wind call. It is always a guess. Some are better at it than others. But I think most LR hunters would agree that the wind is very often the criteria that limits the range they are willing to shoot. The higher the bullet's BC, the more error you can have in your wind call and still be successful. That is science. That is fact. And that benefit ALWAYS matters at any range. And at even a few hundred yards, with a strong wind, the drift difference between higher and lower BC bullets is dramatic.

Too bad it isn't as easy as just loading up the heaviest/highest BC bullet per caliber and going and shooting, just doesn't work that way. What Mr. Sherm is getting at is that velocity does play a part and that there is a point where a given cartridge cannot push that long heavy bullet fast enough to see much (if any) performance over a slightly lighter/lower BC bullet with more velocity on its side. It can be a balancing act.

 

[Capt RB]

The sooner you take a bullet out of yaw the more consistent it flies. Only way to do that is twist rate. Run the berger stability calculator and you will see increasing the velocity has a minor effect in the stability factor. Increase the twist rate and the number jumps. Over spinning the bullet without blowing it up will increase the bc of that bullet. It will also improve the transonic predictability for a firing solution.
Ruger and Browning are offering a 9tw from the factory as of today. An 8tw in the 300win would be optimum for the heavy solids and the new 230 Sierria's. The 245 Bergers Idk about yet but it would seem they will like the faster twist. But they would also benefit from a bigger case like the rum or .590 case head cartridges.

 

[L.Sherm]

You absolutely DO gain something, and its a lot. First of all, usually as bullet weight increases in the same caliber and bullet type, so does Ballistic Coefficient. Pushed to equal pressures, the higher weight/ BC bullet will always have more energy. And that disparity will only increase with range. At greater distances, the difference in energy states can be significant. But it is also true that at shorter distances, that difference can be irrelevant.

But to me, the following is the main reason to use the highest BC bullets you can, and the concept I think you're overlooking. WIND. If your rifle/ ammo combination is accurate and consistent, and your target distance is known, dialing in the proper elevation to effect a proper impact VERTICALLY becomes fairly straight forward. But the big spoiler and often limiting factor for us mere mortals is HORIZONTAL deflection, i.e. the wind call. It is always a guess. Some are better at it than others. But I think most LR hunters would agree that the wind is very often the criteria that limits the range they are willing to shoot. The higher the bullet's BC, the more error you can have in your wind call and still be successful. That is science. That is fact. And that benefit ALWAYS matters at any range. And at even a few hundred yards, with a strong wind, the drift difference between higher and lower BC bullets is dramatic.

A 6.5 140 VLD at 3220 f.p.s I'm using my 6.5x300wsm as an example has a .307 G7 b.c drifts 10" at a 9 o'clock 10m.p.h wind at 500 yds. A 6.5 .340 G7 at the same speed drifts 9" 1" difference at 500 yds. 6" at 1000.
Now drop the velocity to 3150 probably what it would be with a 150-155 class bullet you have zero gain at 500 and probably a couple inches at 1000. How many hunters are good enough to make a couple inch wind call difference at 1000, I'm not.

 

[Capt RB]

A 6.5 140 VLD at 3220 f.p.s I'm using my 6.5x300wsm as an example has a .307 G7 b.c drifts 10" at a 9 o'clock 10m.p.h wind at 500 yds. A 6.5 .340 G7 at the same speed drifts 9" 1" difference at 500 yds. 6" at 1000.
Now drop the velocity to 3150 probably what it would be with a 150-155 class bullet you have zero gain at 500 and probably a couple inches at 1000. How many hunters are good enough to make a couple inch wind call difference at 1000, I'm not.

I just ran the 140 eld and the 147 At your 3220 in the 4dof solver. 2.01 moa vs 2.77moa @500 w 10mph 9 oclock wind. In my creed I cannot get the speed advantage with the 140-142 class of bullets over the 147's My es with 147's was 6 over 10 shot strings. ES with 142's was 18 more importantly, I could not get the 140 class of bullets to shoot above the same velocity I could with the 147's in my rifle. At below 2830 particularly 2780 I would see better groups in no wind conditions inside of 300yds. I didn't shoot a single 140's class group better than the 147's beyond that. This using the 142 mk and 140 target vld.

 

[L.Sherm]

I'm not posting things to start an arguement I'm just trying to get across dont get caught up in the hype, if you got a good load in your gun and switch thinking your gonna get better run the numbers and ask yourself is all the time and money worth it.
If it is then by all means do it.

 

[aebhunter]

If your rifle/ ammo combination is accurate and consistent, and your target distance is known, dialing in the proper elevation to effect a proper impact VERTICALLY becomes fairly straight forward. But the big spoiler and often limiting factor for us mere mortals is HORIZONTAL deflection, i.e. the wind call. It is always a guess.

Great post. Ever since I started dabbling in some practical rifle steel matches I have learned that this is the limiting factor 95% of the time. This fact has led me to be ultra aware of the wind in hunting situations, and has also made me rethink my "effective range". The difference between a hit in the vitals and a hit in the shoulder or guts is often in this very important calculation. I see this overlooked ALOT in the new mainstream LR craze. I have seen the wind do some really crazy things to bullets at distance and if I have a doubt in my mind, I don't shoot.

 

[Hookdown]

Too bad it isn't as easy as just loading up the heaviest/highest BC bullet per caliber and going and shooting, just doesn't work that way. What Mr. Sherm is getting at is that velocity does play a part and that there is a point where a given cartridge cannot push that long heavy bullet fast enough to see much (if any) performance over a slightly lighter/lower BC bullet with more velocity on its side. It can be a balancing act.

Nothing in this game is "easy." And I'm too busy to argue the point endlessly. But suffice it to say that thousands of LR hunters and PRSers would beg to differ with your assertion. If your rifle is already built, you may or may not be able to take advantage of high BC bullets. But if one is still in the building/ acquiring parts stage of a rifle build, there is not that hinderance. BC is science, math, and it isn't subjective.

There are reasons not to automatically just choose the highest BC bullet and go hunting. Bullet construction, terminal performance, accuracy, MPBR, or other aspects may dictate other choices. But again, as range increases, wind becomes the great spoiler. And your best weapons against that effect is knowledge and BC.

 

[NEMTHunter]

I shoot the 215 Berger in my 06. If I switched to the 230 Berger I would loose down range trajectory. Why? Because the lose of speed going from the 215 to the 230 would make the 230 not as flat shooting in my application.

The same thing apply's to the 300win mag. If you cant get the velocity needed. The extra BC will do you no good.