Bullet weight ..vs..Twist rate,

JustC

I hear folks saying all the time that this and that bullet have this and that range of bullet weight available and they see this as a viable consideration for purpose and use. Now, I have found that there is always one weight (or several within a close grain weight) that the barrel will push correctly due to it's twist. That being said, I fail to see how the range of bullet weights available plays any important role in that rifle's existence. I know that by handloading, you can charge the powder up or down to get another weight to group up on paper, but why not just buy a larger or smaller rifle to do the same thing? My opinion is that if your gun shoots a 180gr bullet the best, then that's all you should be shooting. If you want to hunt varmits, then it sounds to me that you need to be hunting them with a 180gr bullet, because that's the one that is the most accurate in that rifle. Why change weights and create handloads to do the same thing that the original accuracy load can do? Is it just me? What do you guys think?

A great rifle with a junk scope,....is junk.

beachmaster73

Just c....I guess I'd say that for every caliber and barrel twist there is a certain weight bullet that will perform best out of that rifle. That is not to say that the rifle cannot shoot other bullets with reasonable accuracy only that a certain weight bullet provides the maximum potential. As an example I have a 1 in 12 twist Navy Mark II M1. At 200 and 300 yards I achieve superb results with straight LC 147 grain ball ammo. That ammo is on the outside edge of the accuracy envelope at 600 yards where I normally shoot Match 168 grain bullets. I believe that shooting a 155 grain Palma BTSP at a higher velocity than the 147 grain ball ammo would achieve accuracy results similar to the 168 grain. This doesn't address knock down power at extended range though and that would have to enter the equation for practical use of a given bullet..i.e. a 140 grain bullet might be more accurate out of my .30-06 but if I'm going after brown bear I might feel far more comfortable with a 220 grain bullet in the chamber......Now of course if you want to use your question to justify purchasing many new rifles I think that would be a great idea too. Let's see..I need a 45 gr rifle, a 55 gr rifle, a 62 gr rifle, a 69 gr rifle, a 77 gr rifle, an 82 gr rifle, a 130 grain rifle, a 150 gr......hey this is fun!!!! I may have justification for an entire new collection of weapons before the end of the day! Beach

JustC

Beachmaster73 ...I have several friends who's military match shooting experiences mirror yours with that rifle. They tell me that out to , I think it was 600-700yds, the 168 match performs best, but then from there to 1000yds, the 173 match (lake city) and handloads with the 173gr work the best. Now from what I understand, the physics of bullet weight vs gravity and wind deflection comes into play and therefore determines the weight to be used for each distance. However, the difference between 168 and 173, is minimal, but enough to win or lose the match at 1000yds.

Now, let's make an assumption of a given and known distance, say 300yds. There will be one bullet which will perform best at 300yds, correct? Let's also not take into account that one can handload another weight with more or less powder and make it group very well at that given distance. However, many times the powder must be decreased to gain these results, and therefore you have diminished the knockdown power of that particular cartridge. I see it this way, and correct me if I'm wrong, as you have lots more competition experience than I do, and I am interested in your experiences past 500yds, but, if you have a bullet that performs best, at near or 90% max load, then you have gained full potential. If the bullet weight has been changed, and the powder charge changed, and performance lost to achieve a group, havn't you effectively changed that rifle into having the performance of a smaller caliber that would have shot the same weighted projectile with the same results? I don't see the logic unless someone just wants to say "I can use my rifle for this and that and something else and blah blah blah". I have a Sendero in 7mm mag which will shoot one ragged hole at 100yds with federal premium 150gr nosler balistics right out of the box. If that is the best shooting load I have found, even if I handload the 150gr, then wouldn't it make sense to varmit hunt as well as elk hunt with the same bullet? Or is there something I am missing here? What I see happening is that some of the less experienced members are asking questions about what caliber to buy, and they are receiving advice which makes little or no difference to their needs, due to the fact that they probably don't handload, seeing as how they are asking basic questions about what kind to buy to hunt with. Isn't that a little misleading or clouding the issue a little? I have always found the bullet which clearly outperforms all other bullets in my rifle, whatever rifle, and then stick with that bullet weight/design. Even if you handload, you have still found the correct bullet for the recipe. Am I totaly off base here, or am I just more particular about grouping than the average weekend hunter?

I notice you also picked up on my underlying motive for purchasing new rifles. Don't let it slip out to the wives, or we are stuck with what we got and can't justify another one with examples of balistics that totaly confuse them and therefore, trick them into agreeing with us.

Also, I would be interested in talking to you about how one might go about getting into competition.

A great rifle with a junk scope,....is junk.

He Dog

JustC, another consideration, given your tenent that a rifle will shot one bullet weight "best," is that it will shoot other weights well enough for hunting purposes if not competition. Thus, with a .30-06 you can change bullets and hunt pronghorn to moose. It may be best with one bullet but good enough with others. Now, I certainly agree that one really should have a rifle for every job, and every day of the week plus holidays, but when I started, I looked for one caliber, one rifle that could be coaxed into doing everything. Only later did I discover that I really needed many more. Some folks only want one, some perhaps, can only afford one. As long as they have a good scope, you would not want them to have none in preference to one if they could not afford them all would you?

A balanced diet is a cookie in each hand

JustC

He Dog,...As always, your logic is well founded and accepted as that of someone who has experience in the field. I can tell we see many things the same and probably beleive in many of the same calibers. You do in fact bring to light something I was thinking, but forgot to mention in the previous posts, which is that of hunting applications. Most guys won't go past a max of 200yds and will let the game walk at distances past that. I must respect that attitude, because if you havn't punched a "jag" of paper at distance, it would be unethical to try a "pot shot". I should have clarified that I often have a shot of 300-500yds, and therefore must be sure about the load, both in accuracy and knockdown at long range. But for the person who is just getting into it, yes 1moa or even 2-3moa would provide ethical harvests and is therefore plenty acceptable.

And no, I would not want one to go without a rifle. I feel all able bodied americans should take time to immerse themselves into a tradition which is as old as our country itself. After all, it is the tradition which helped to create the U.S. One good rifle and One good scope will provide a man with all he needs, then he just has to learn his balistics. A wise man once told me,..."fear the man with one rifle, not the man with many rifles, the man with one rifle knows how to shoot it, because that's the only one he shoots"

I just wanted to know if I was the only one who sees things that way.

A great rifle with a junk scope,....is junk.

whiteclouder

JustC

Don't get all tangled up in the minutia. All that is required is that a bullet spins fast enough (but not too fast) to stabilize its flight. A given twist will stabilize a range of bullet weights and a range of velocities. That factor is what makes venerable old cartridges like the 30'06 and the 270 so great. Pick a .224 to a .257 and use it to bust varmints. Pick a .308 thru .340 and bust the big stuff. You only need two to do all the shooting you will ever desire.

That doesn't mean you can't buy one of each type over the course of your life and try them out. I did.

Clouder..

Wild Turkey

Just to add a little more confusion to the situation -- the bullet design affects the spin rate, too. For example, a round nose, flat base bullet will act differently than a boat-tail hollowpoint.

I remember seeing a study that found bullets actually "wobble" around a central axis going downrange. Matching range and bullet design are what gives the best groups.

Note on long-range rifled bullets: the Army found that at extreme ranges (1000+ meters) tanks had to start adding some "drift" because of the spin of the bullet. New tanks with smoothbore guns don't have that problem.

Realistic question: How big is the vital spot on you favorite game? Is any group smaller needed? Also-when hunting what happens if game shows up at different ranges than your zero? If you've put a lot of work into "best group" will it be effective at longer ranges?

Long range shooting fascinates me, but I can't do any now. I'd love to try the "black powder metallic cartridge" siloutte shooting. Just can't find enough clear space here in Kentucky!

just my too scents--

Wild Turkey"if your only tool is a hammer, you tend to see every problem as a nail"

redcedars

Ballistics is a great subject of study. Start out with The Bullet's Flight by Mann and go from there.

In broad terms, all other things being equal, within a given caliber, heavier bullets are longer, and require higher rpm to stabilize. (They will also have greater sectional density, and therefore a better ballistic coefficient.) Higher rpm can be achieved by a faster twist, or higher velocity, although there are practical limitations on both factors. So as Clouder points out, a given barrel can shoot a variety of bullets with varying degrees of accuracy. There will be optimum loads, and probably a bunch more that are acceptable.

The actual path of a relatively stable bullet is a spiral around its trajectory.

redcedars

JustC

I see several of us look at it the same way I do, Scientificaly. If the twist rate determines that with any given caliber, it will shoot between this and that weight bullet best, those are the ones I shoot to find the rifles accuracy load. I don't kid myself into thinking that by adjusting powders and other factors, to shoot a bullet which doesn't necessarily agree with the twist rate, at it's designed velocity, that I have actually acheived something. I shoot the load that performs best at near or full velocity, that is the accuracy load. I am glad several of you approach the issue as I do, now I don't feel like so much of a fanatic. I order my barrels with the twist rate that I want, because I have already decided on the bullet weight/weights that I am going to use. Purpose of rifle=1st, design specs to meet purpose=2nd

A great rifle with a junk scope,....is junk.