revolver barrel twist

[gunsbrad]

I am a new member here but have been lurking for a while. I have read a lot of posts related to optimum bullets in ruger 44 and 45 revolvers. I was wondering if I could get the thoughts of some of the experienced on this forum. Assuming correct dimensions in the revolver throat, barrel, trigger etc. What are the optimum bullets/velocities in these guns(in your opinion).

Thanks

Brad Hurt:castmine:

[felix]

Hard to say what the best twist would be because of the long freebore, the distance from the case end to the beginning of the lands. Faster the boolit hits the lands, the more boolit destruction, which requires more and higher lands to compensate. A longer barrel also compensates, giving more time for the boolit to rotate faithfully. Experience shows that 20 twist is about right for most boolits in the 44, assuming standard land configuration. The 45 is at 16 twist standard, but that is too fast in my opinion, and should be more like 22. Add 4 to each of these for good rifle twists using standard boolits. ... felix

[Bass Ackward]

Brad,

What twist rate you need depends on the bullet weight and velocity potential of the cartridge. Take 45 caliber. 45 AR is 15 twist, Colt is 16, 454 Cassul is 24 twist. And no matter what twist rate you have, a longer barrel gives you more velocity so that you don't need as much twist, which is why Felix says rifle twists can be slower.

And as a result, you will usually hear guys say that the only way they get any accuracy is to run it right on the top. That is generally where a gun is set up to stabilize. Some guys like longer barrels for cast. Kinda the same thing. If you hollow point, you throw the weight to the rear and stabilization will happen at a lower velocity.

So what you need, depends on cartridge and bullet weight.

[gunsbrad]

Thanks for the replies and I am sorry if I miss stated the question, but I am not asking about optimum twist. What I am interested in is optimum bullets and optimum velocities of these bullets in standard ruger sa 44 mag and 45 colt revolvers.

This is assuming good internal dimensions in the revolver. I have seen a few hint at some different experiences in other threads, and I was hoping those would chime in and throw out some of the ample light that seems to be on this forum.

Thanks again

Brad

[shooting on a shoestring]

Concerning my experience with .45 Colt, 7.5" Blackhawk, the shorter the boolit the better. The moulds I have for it are:

454424 SWC 250 gr, 454190 Round with tiny flat point 250 gr, 452490 SWC Gas Checked 250 gr, Lee 300 (or maybe 310, can't remember for sure) Wide Flat Nose Gas Checked, and the Group Buy Lee/Catshooter 310 Keith SWC

I've run them all between 800 and 1200 fps, some to 1300.

Hands down favorite is 454424. Usually run it 900 to 1000 fps with Bullseye or Herco, does 2" groups at 25yds. That's the best I can do with my skills and iron sights.

A close second is 454190. It tends to lead as it gets over 1100 fps but I don't shoot many rounds faster so its ok. The round flat point should be more areodynamic and perhaps a bit more accurate at 50yds, but I can't tell it.

452490, I don't shoot much b/c it needs gas checks, but it is as accurate as 454424 and I've run it to 1300 fps with 2 to 3 inch groups at 25 yds. If I was to hunt with this gun, I'd use this boolit.

The 300 grainers just haven't been very good groupers. Usually I see 3 to 4 inch groups at best with the Lee WFN gas checked, and usually over 4 inches with the 310 Keith SWC. Velocities running 1000 to 1200 with H110, Lil'Gun, 2400 and H4227. I've been disappointed in my results with the 300 grain boolits. I realize part of it may be due to the recoil, I just don't shoot as well as with the lesser recoiling 250's.

I'm not an expert, but I that's my experience.

By the way, .45 Colt is a hoot to shoot. I love it, but have intentionally started shooting more .357s just to conserve lead. That .45 Colt can go through a lead pile like a 4 door dually goes through gas.

[felix]

Next time out, shoot several of those heavy jobs with the same load as before into a backstop area that you know you can find the boolits. You don't need a target. Look at the best looking boolit assuming you can find more than one. Notice how much stripping took place towards the nose of the boolit, exhibited by wide land marks. The land marks should be near perfect at the rear of the boolit for the boolit to shoot half way OK, even at 25 yards. Any more slippage than half way down the bearing surface on the boolit is too much for distance shooting. You need a shorter, and/or more bearing length of a style to shoot better in that gun at that velocity. ... felix

[9.3X62AL]

+1 to Shoot/Shoestrings comments on the 45 Colt. In 44 Special and Magnum, I am very fond of both #429421 and #429244, which are standard weight SWCs. From 750-1200 FPS+, they shoot very well for me.

[44man]

1 in 20 for the .44 and 1 in 16 for the .45. It is not true that light boolits shoot better. I use 320 to 330 gr's in the .44 and it will shoot from 240 gr's up.
The .45 will shoot from 250 to 350 gr boolits.
I NEVER shoot closer then 50 yd's and if I don't get an inch or less I grit my teeth. Some of my best groups are with heavy boolits and 296 powder.
Here is what my Vaquaro does at 50 yd's with a 347 gr Lyman boolit.

[44man]

Felix, that is the reason I use hard boolits. I do NOT believe that a boolit needs to be close to the rifling or forcing cone. My 45-70 BFR has such a run to the end of the cylinder that you need a flashlight to see the boolit down that hole.
I am running 1632 fps with a 317 gr boolit and I don't know what with a 378 gr but both will do an inch or less at 100 yd's.
Here are some groups at 50 yd's.

[felix]

44man, true what you say. As long as the boolit spins faithfully, your accuracy will be splendid. ... felix

[44man]

Notice the left group is 3 shots in about .450 and the right center group is 5 in 7/16".
I know all of you know I hate semi wadcutters in any form and this is why. I just can not get any of them to shoot like this.
My goal is to get everyone here away from 25 yd's and to realize what their revolvers can do.
2" at 25 yards would turn my gun into a safe queen! [smilie=1:
My best group lately with my .44 using my 330 gr boolit was 3 shots in 1-5/16" at 200 yd's.
My friend brought over a brand new BFR. 10", 45-70 last week. I loaded some of my 378 gr WFN boolits for him. I mounted his red dot and it only took 5 shots to center it at 50 yd's. Each 2 shot group before I hit center was 1/2".
I swung to a liter bottle of water at 100 yd's and blew it up. I had some 1-1/4" pieces of a spray can tops on sticks down there and they vanished! :drinks:
Of course I use Felix lube too! :mrgreen:

[anachronism]

Brad, you'll find your Rugers shoot very well with most bullet weights. Is there anything special you'd like to accomplish with them? Are you just looking for a decent plinking load, or are you planning to take them hunting? Not all combinations work well in every gun, and most people are content with bullets in the 250 gr range for either caliber for most purposes. If you want to get into the heavyweights, and the super-heavyweights, that often requires a bit more effort.

[gunsbrad]

I have been shooting and casting bullets for many years and have experiences with both of these cartridges, but have never gotten 1" groups @ 25 yds from a factory gun. 1 1/2" is about the best. I have used mostly 250 grainers in both cartridges although I have done some pretty good shooting with 300+ bullets in the 45.

What I am interested in is more ideas on this than basic nuts and bolts. I had read some interesting ideas on what these guns prefer(based on twist) and this is what I was looking to explore.

Thanks for the replys.

Brad

[44man]

I love the LBT style truncated cone boolits for accuracy. I think they center in the forcing cones straighter.
There are only a few things needed for accuracy, a decent fit to the throats and good neck tension. That is the only reason I use harder lead, so the brass can't size my boolits when seating. Water dropped WW's works fine at about 20 BHN.
However boolit design is also very important and I have tested about 50 semi wadcutters for all of my calibers recently and none gave me super groups. Some were decent but nothing to brag about.
Ruger's will shoot with the best of them. S&W's are SUPER accurate but grip sensitive. Overall, the easiest guns I have found for pinpoint accuracy have been the BFR's. They seem to shoot any boolit I come up with EXCEPT semi wadcutters. Even light LBT types for the rifling twist will outshoot them.
Here are some BFR twist rates;
.475 is 1 in 15"
45-70 and .450 is 1 in 14"
.460 is 1 in 20"
.454 is 1 in 20"
.500 S&W is 1 in 15"
Desert Eagle .44 is 1 in 18"
Notice all are pretty fast but the range of boolit weights I have been able to shoot baffles me as to how easy it is to work an accurate load.
The 1 in 20" twist for the Ruger .44's also works fine and I have pop cans here I shot at 200 yd's with the SRH I had. No problems holding 1/2" at 50 yd's.
Don't give up, they WILL shoot. My secret is that I am never satisfied. [smilie=1:
There is one make of gun that drives me nuts but I won't mention it. :mrgreen:

[gunsbrad]

I haven't had a big bore revolver in about 2 yrs due to a divorce. I was going to order a 45 blackhawk to replace the one I had,(and probably will later) but the 50th ann. 44s were on sale and I thought here is my chance. I got it in Friday and as I reported in another thread it is on its way back to Ruger.

I have shot mostly Keith style swc bullets in the past and I have shot a lot of them. I am in on the keith 44 group buy right now( my first). Since finding this site I have read disparaging remarks about keith bullets. Specifically what are some bullets you would recomend for the 44 and 45 cal Rugers in the 250 to 300 grain weight range. I shoot wheel weights almost exclusively, water dropped most of the time. If I can come up with 1/2" to 1" groups at 50yds it would sorely beat anything I have done.

I do shoot frome a rest and record my results.

[9.3X62AL]

Brad--

The Keith-type or SWC boolit form has two kinds of commentary--those who swear by them (my view) and those who swear at them--and that camp is well-represented in this thread!

I've had generally decent accuracy with the SWC design in most revolvers in several calibers over the past 30 years or so. I don't have and haven't owned any "premium" revolvers like a BFR or a FA, just factory-grade general purpose wheelguns by Colt, S&W, and Ruger. I do use some heavy-for-caliber boolits, and some round/flat noses as well. In my experience, neither variation has resulted in better overall accuracy for me--but the combination of my skills and the revolvers' limitations make 2" @ 25 yards about as good as it gets for me. My eyesight is going to h--l in a handcart, which isn't a big help either.

[jandbn]

Sorry to have revived this thread with my first post, but I didn’t think it necessary to post a new thread when my question about twist rate is so directly related to optimum bullet weight. After hours and hours of lurking prior to and after registering on CB (my home on the Net) I came to the conclusion (too much to choose from) that my next firearm purchase will be a Stainless Ruger Black Hawk or Bisley in 45 LC with a 5 1/2” barrel. (I’m still undecided as to which grip style at the moment.) Twist for either revolver is 1:16. Opinions here are to use a boolit in the 260-330 grain range. My preferred boolit will be primarily for deer and hopefully be a WFN in the 1100-1200 fps neighborhood.

The majority of general consensus on CB for hunting revolvers seems to be heavy for caliber and most everyone here has their favorite two or three recipes for a specific gun with stable bullets being the norm. I haven’t been able to find any posts where someone had calculated a handgun’s optimum boolit(s) based on given parameters such as desired boolit weight and velocity. The only referenced methodology for finding the “optimum bullet(s)” seems to be to find those two or three go-to loads for the specific handgun by a lot of pleasurable shooting via trial ’n error.

Now with all the time I have spent researching and reading up on my future purchase plus being one of “those types” that has to know for not other reason than just to do it, I figured why not calculate an optimum bullet based on the revolver’s twist and desired boolit velocity. After all, I found all sorts of firearm related calculators and formulas on the Net to use for computing everything else under the sun. (Most firearms related calculators and formulas pertaining to revolvers are not applicable in the real world as a dead deer is a dead deer.) Well the calculations haven’t panned out. My inquiring mind “needs” an explanation as to why the twist calculators and formulas that I have found on the Net don’t jive with the manufactures’ twist rates.

Every twist calculator or formula I tried using a .452 300 grain WFN at 1100-1200 fps gave a twist rate of well over 30. The same goes with other .452 boolits of various lengths and weights. The 44 Mag handguns follow this same trend of twist ratios. Yet revolvers produced by manufactures have twist rates of 16 to 20‘ish. Even using Don Miller’s Twist Calculator, which is a more modern version of the Greenhill formula and has been made part of other ballistic software programs, computes similar twists that drastically differ from manufacturers’ revolver twists. Is every twist calculator and formula “biased” toward rifles? How do manufacturers determine what twist to use in handgun length barrels? Does anybody know of a twist calculator or formula for handgun length barrels?

Felix? You seem to be rather adept (and then some) at math! Can you provide an explanation of the disparate twist rates if there isn’t a semi-accurate twist formula for handgun barrels?

44man? With your revolver experience and seeing as how you are so proficient at “thinking out of the box” (for which you deserve many kudos) plus tout twist rate as one of simpler means to the accuracy you have shown in your infamous target pictures, maybe you have an opinion or knowledge to share?

Anybody else care to comment?

[44man]

There is no paperwork in the world that works. Ask me about the stupid Marlin 1 in 38" twist in the .44! None work for a rifle either.

As far as I am concerned, shooting various twist rates with intended boolits for the caliber is the only way.
What I have found with revolvers is the faster twist rates will shoot a much wider range of boolit weights and shoot them all very well. I do not need just one specific boolit. Each boolit will have a sweet spot without ever reaching a max load for the powder.
The Ruger .45 with the 1 in 16" will shoot anything I stuff in it from 250 to 350 gr. The .44 will shoot from 240 to 330 gr. (heaviest I have)
When the twist gets slower, the top weight it will handle drops drastically. To shoot heavier boolits you need to up the velocity and pressure too much to suit me.
The strange gun is the BFR 45-70, it loves a 300 gr bullet or boolit yet still packs little groups with a 420 gr which is the heaviest I have tried. I expect it will shoot much heavier too. It doesn't seem to matter what I use. I cut the last WFN cherry for a mold by just looking at it as I filed the nose and just cut lube grooves by eye. It came out 378 gr and breaks 1" at 100 yards if I do my part.
Now who would expect a 1 in 14" twist would ever work in a 45-70? Run that through Greenhill once! :mrgreen:
My BFR .475 is the same. I have shot as light as 350 gr decent but it just starts to come on with 400 gr and it shoots everything up to 460 gr.
My suggestion is to pick a boolit you like and work loads for it.
I had to delete pictures, I was filling up my allowance.

[shotman]

And then S&W come up with the Gain twist for the 460. Its one fine gun and every time I shoot it ,I just look at the groups and wonder why they didnt do that before. It has shot the 185gr as good as the 310gr. I load a 45acp load in schofield brass and a 45 colt with a 252 and the 310gr in a 454 brass and all do well

[44man]

And then S&W come up with the Gain twist for the 460. Its one fine gun and every time I shoot it ,I just look at the groups and wonder why they didnt do that before. It has shot the 185gr as good as the 310gr. I load a 45acp load in schofield brass and a 45 colt with a 252 and the 310gr in a 454 brass and all do well
The reason for the gain twist was bullets were stripping the rifling at the high velocities.
My friend has been shooing a borrowed .460 and he is also amazed at the accuracy.
But then again, it is hard to find any S&W that does not shoot.

[jandbn]

It sure is a good thing there are decent folks here willing to share their knowledge and experience. If I, or anyone for that matter, anyone else were to assume an optimum boolit based soley on currently known calculators and formulas for barrel twist rates, a person sure would be scrathing their head wondering why manufacturer's produce the twist rates they do in handguns.

Maybe we can "taunt" Felix into using his genius to give us some semblance of an accurate twist formula for revolvers? I know figuring something like that out is way over my head. It just seems that with all the technological advaces today, somebody could figure somethig out!

The flip side of the coin is each firearm does its own thing anyway so I guess all is well as we can always have a lot more fun just shooting to find that optimum boolit rather than try calculate it.

[felix]

Yes, it can be done, but not without duress. The assumptions involved for the most appropriate solution are not practical in the field. Like the posts above, we are talking boolit slip and sliding from ignition throughout the barrel exit. In a true pistol, like in the ACP, we can use twists set for rifles, with additional compensating twist for the lack of velocity. For example, about 5 years ago I noticed someone made match barrels for their pistols at 24 twist. They actually made one for the 1911 as well, and I was tempted. That would have been marginal at 50 yards using bullseye HG68 loads. ... felix

[StarMetal]

The reason for the gain twist was bullets were stripping the rifling at the high velocities.
My friend has been shooing a borrowed .460 and he is also amazed at the accuracy.
But then again, it is hard to find any S&W that does not shoot.

Why would the S&W 460 strip bullets at high velocity when 223 with 7 twists and 22-250's with a 9 twist don't?????

I'm not sure that is the reason. I'm thinking more along the lines to keep pressure down because of more resistance of a one rate fast twist or whatever twist.

I may be able to find out though from my very good friend at Lothar Walther, I believe a while back he told me LW made their barrels.

Joe

[S.R.Custom]

...What I am interested in is more ideas on this than basic nuts and bolts.

Actually, I'm not very concerned about twist in the .44 revolvers and what bullets they will and won't stabilize. When you start looking at the data, you see that when you get heavier than 240-250 grains, the muzzle velocity drops off to the extent that kinetic energy and momentum both begin to suffer; so much so that even at 100 yards, the retained energy of the 250 gr bullet is still more than the 300, despite the vastly superior BC of the 300 gr bullet. In other words, a bullet heavier than 250 grs in the .44M is essentially a waste of lead, and I'm sure the engineers at Ruger had this in mind when they cooked up the twist rate of the SBH-- they decided on the twist rate that gave the best accuracy in typical 240-250 gr .44M loadings.

I've not done much work with the .45, but I'm guessing the faster twist rate of the .45 owes to the fact that it's a slower cartridge; crunch the numbers and you'll probably find you have to use a faster twist to get an optimal spin for a 250 gr slug only going 800 fps.

[44man]

Actually, I'm not very concerned about twist in the .44 revolvers and what bullets they will and won't stabilize. When you start looking at the data, you see that when you get heavier than 240-250 grains, the muzzle velocity drops off to the extent that kinetic energy and momentum both begin to suffer; so much so that even at 100 yards, the retained energy of the 250 gr bullet is still more than the 300, despite the vastly superior BC of the 300 gr bullet. In other words, a bullet heavier than 250 grs in the .44M is essentially a waste of lead, and I'm sure the engineers at Ruger had this in mind when they cooked up the twist rate of the SBH-- they decided on the twist rate that gave the best accuracy in typical 240-250 gr .44M loadings.

I've not done much work with the .45, but I'm guessing the faster twist rate of the .45 owes to the fact that it's a slower cartridge; crunch the numbers and you'll probably find you have to use a faster twist to get an optimal spin for a 250 gr slug only going 800 fps.
I do not know where you get your information but it is wrong. Given two boolits, one light and one heavy with the same basic profiles, the heavy one will ALWAYS have more sustained velocity and energy at range then the light one even if started a little slower.
But lets say you start both at the same velocity to start with. The boolit that is 100 or so gr heavier will have close to double the energy at 500 yards.
Now reduce the velocity of the heavy boolit by 100 fps which is about right for the difference in the 250 to 300 gr in the .44, you can still have a good 300 fp of energy more from the heavy boolit at 500 yards.
This holds true at all ranges. At closer ranges the heavy boolit has even more energy and will not lose it as fast as distance increases.
Pick the accuracy point of each .44 boolit I shoot, the 245 gr at about 1420 fps and the 320 gr LBT at 1316 fps, go to your book and plot the energy figures from 50 to 500 yards.
I think your eyes will be opened very wide! :Fire:
Then shoot the steel ram at 500 meters with your 250 gr boolit and then with the 320 gr and tell me which one will leave the ram standing and which has the most momentum!!!
I can tell you one thing, if I were to shoot an elk or larger at 100 yards, the 250 gr boolit will stay home.
You are printing mis-information that only confuses the poor fella asking questions.
Extra boolit weight is NEVER wasted.
Go to the .45 Colt in a Ruger with a 250 gr boolit at about 1300 fps and compare it to my 343 gr boolit at 1167 fps, work out the energy, then tell me which one you want me to shoot at you at 500 yards. I think you will find the heavy boolit has the edge in energy, momentum and penetration.
Here is a 330 gr, .44 boolit at 200 yards from my SBH. Does this look like the twist is wrong?

[felix]

The reason, Joe, is accelerating the boolit's rotation. Wider projectiles are progressively harder to do without stripping. ... felix

[44man]

The ONLY thing affected by boolit weight is trajectory.
Let us compare the .44 to the 45-70 and .475 revolvers with heavy boolits.
The .44 will drop about 35" at 200 with a 50 yard setting. The 45-70 will drop about 16" and the .475 only drops 18" with a 420 gr boolit.
The big difference is boolit weight with the .475 at the same velocity as the .44, far outstripping drop figures while the 45-70 uses a little more velocity to flatten trajectory.
The .475 is FAR more potent a killing machine then any other because of the boolit diameter and weight.
I do not sit at a desk and make up stuff. I shoot and hunt and know what heavy boolits do.
Supermag, have you ever shot revolvers to 500 meters? :confused:

[Bass Ackward]

Actually, twist rate is not for those that do everything right. They are more for the masses to do what will perform the best over an entire bullet weight range for the practical power limits and ranges of the caliber. Sort of how the guns will be used with a minimum of effort for the largest amount of people.

Twist rate is really a range determiner since only velocity is lost. And the worse you launch something, the faster you have to spin it to hope to achieve the same accuracy / range. Which is why accuracy varies for all of us as we change load conditions. If it were simply a velocity level and spin rate, then all loads that produced that combination would shoot the same. Particularly in a handgun where you don't have bedding or vibration issues.

The longer the barrel, the less twist rate is an issue and the slower you can go with it. The shorter the barrel, the more critical twist rate and bullet weight become.

[44man]

Actually, twist rate is not for those that do everything right. They are more for the masses to do what will perform the best over an entire bullet weight range for the practical power limits and ranges of the caliber. Sort of how the guns will be used with a minimum of effort for the largest amount of people.

Twist rate is really a range determiner since only velocity is lost. And the worse you launch something, the faster you have to spin it to hope to achieve the same accuracy / range. Which is why accuracy varies for all of us as we change load conditions. If it were simply a velocity level and spin rate, then all loads that produced that combination would shoot the same. Particularly in a handgun where you don't have bedding or vibration issues.

The longer the barrel, the less twist rate is an issue and the slower you can go with it. The shorter the barrel, the more critical twist rate and bullet weight become.
That was very well said! :drinks: Shorter barrels should have a faster twist. Cost to gun makers would be too much. A happy medium needs to be reached but it is sad some gun makers ignore proper procedures by testing and just go to out dated cannon figures worked out by some pencil pusher at a desk.
Talking to Marlin is like talking to the US Congress! :(
A few revolver makers are out of the loop and stubborn as all get out too.
Some revolver makers do not expect anyone to shoot more then 7 yards either.

[S.R.Custom]

Given two boolits, one light and one heavy with the same basic profiles, the heavy one will ALWAYS have more sustained velocity and energy at range then the light one even if started a little slower.

I never said any different. What I said was --from the SBH-- the 300 grain bullet starts so much slower than the 250 grain bullet INITIALLY, that it doesn't make much sense to fool around with anything heavier. To wit:

From my 7.5" SBH and a 250 gr LSWC, I can shake 1503 FPS (mean) as measured at 20' with an Oehler 35P. The most I can coax out of the 300 gr LSWC, on the other hand, is 1217 fps. Any more, and the primer pockets start to loosen. (And both of those figures, incidentally, surpass just about any published numbers for 'safe' loads.)

If we take that data and apply it to the ballistic tables found in Sierra's 3rd, we see that it takes the 300 gr bullet 250 yards to "catch up" to the 250 grain bullet in retained energy and momentum. And if we're smart and the purpose of our shooting is bullets-on-game out past 250 yards, we're not using the original poster's open-sighted Ruger SBH, are we? Anyway, my point in my previous post was that the twist of the Ruger SBH is just fine for anything you're likely to use it for.


...I do not know where you get your information but it is wrong... You are printing mis-information that only confuses the poor fella asking questions... I do not sit at a desk and make up stuff... Supermag, have you ever shot revolvers to 500 meters?

What's your problem? Did I say something that offended you?

[44man]

I never said any different. What I said was --from the SBH-- the 300 grain bullet starts so much slower than the 250 grain bullet INITIALLY, that it doesn't make much sense to fool around with anything heavier. To wit:

From my 7.5" SBH and a 250 gr LSWC, I can shake 1503 FPS (mean) as measured at 20' with an Oehler 35P. The most I can coax out of the 300 gr LSWC, on the other hand, is 1217 fps. Any more, and the primer pockets start to loosen. (And both of those figures, incidentally, surpass just about any published numbers for 'safe' loads.)

If we take that data and apply it to the ballistic tables found in Sierra's 3rd, we see that it takes the 300 gr bullet 250 yards to "catch up" to the 250 grain bullet in retained energy and momentum. And if we're smart and the purpose of our shooting is bullets-on-game out past 250 yards, we're not using the original poster's open-sighted Ruger SBH, are we? Anyway, my point in my previous post was that the twist of the Ruger SBH is just fine for anything you're likely to use it for.



What's your problem? Did I say something that offended you?
No, I never take offense, it is just that heavier boolits have more energy even if they take a microsecond longer to get to the target. To say a lighter boolit has more energy at 100 is wrong just because it starts faster.
But I see the velocities you fool with and the total quest for speed from a revolver. 1503 fps is ridiculous for any .44.
Run my figures and come back, I use sane, accurate loads because ME and MV has never killed anything, only boolit work in the animal does, along with the ability to hit the animal.
But let us use the Lyman chart for .45 boolits. Start a 293 gr boolit at 1400 fps and a 420 gr at 1300 fps.
Energy at 100 is 930 fp for the 293 gr.
200 is 728
300 is 610
400 is 529
500 is 468
the 420 is 1277 at 100
200 is 1086
300 is 955
400 is 858
500 is 782
347 fp more at 100 for the heavy boolit and 314 more at 500.
I might agree with you if you are talking about high velocity rifle loads but they have no place in handgun loads.
Light, high velocity bullets bleed off velocity fast and it will take time for a heavy bullet to match energy, but it does not only match it but will exceed it the farther down range you get.
You can not attribute magic to revolver boolits, heavy hits harder at any range.
I will never be impressed with super high velocity from any revolver, pushing the envelope.
Now please show us 50 and 100 yard groups shot with your super loads! :mrgreen:
Bass is always on me about "Hot " loads but he does not understand, I do NOT load hot, only accurate.
I did not like to quote any book figures like the Lyman because I do not believe they mean much. Neither do the figures you quote.
I put my boolits into practice and see for myself what they do. I can say a 310 gr at 100 is a hell of a lot more powerful then a 250 gr.

[44man]

Supermag, go back to your first post, that is NOT what you said. You did a back track.

[S.R.Custom]

...Light, high velocity bullets bleed off velocity fast and it will take time for a heavy bullet to match energy, but it does not only match it but will exceed it the farther down range you get...

Absolutely. And that'll happen pretty quickly in the case you cite where the two muzzle velocities differ by only 100 fps. And if the difference between the two bullets was only 100 fps at the muzzle, I wouldn't waste my time with the lighter one.

But in the case of the 7.5" Ruger SBH, the difference in max velocities is so far apart between the 250 gr and 300 grain bullets that it makes the 300 grain bullet irrelevant out to 250 yards. Whether it's my own muzzle velocity figures or Sierra's --Sierra uses the 7.5" SBH as their test platform-- the difference in max muzzle velocities between the 240 and 300 grain bullets is 300 fps.

In other words, there simply is not enough barrel hanging off the end of your typical .44 Magnum revolver to make effective use of a bullet weighing more than 240-250 grains. (Ever wonder why the heaviest .44 caliber Silhouette/Match bullet made by Sierra weighed only 250 grains?)


...ME and MV has never killed anything, only boolit work in the animal does...

I'm sorry you have an aversion to the math, but KE and M are but mere descriptors of that "boolit work" you mention. I kind of like them because by consulting a few figures and tables by someone who's been there already, I can keep from wasting my time.

As for posting my targets, well, you wouldn't be impressed. Except for the 7mm Mag elk gun, I don't have telescopes screwed to the top of any of my guns. Besides, you'd have no way of knowing how close I really was to the target. ;)

[9.3X62AL]

I don't have a "calculable" answer for J and BN's question. What I observe is that revolvers (and autopistols) use a twist rate sometimes far faster than what is needed to gyroscopically stabilize their bullets in flight, and I assume there must be--or have previously been--a reason for doing so.

Colt cap-and-ball revolvers used 1-16" twists, for *some* reason.......their usual projectiles were roundballs. Muzzle-loading rifles use a 1-60" to 1-72" twist for roundball shooting.

44 Magnum revolvers use(d) a 1-16" to 1-20" twist, while Marlin used a 1-38" twist (leftover from the 44-40 WCF) in its rifles so chambered.

9mm and 40 S&W often use a ridiculously fast 4 turns/meter or 1-10" twist to launch their short-for-caliber bullets. A slower twist rate can easily stabilize such bullets, and often results in a more accurate pistol/ammo equation. Still, a majority of makers insist on the fast-twist pitch rates in their bottomfeeders.

The whole answer might be something along the lines of "We've done it that way since 18-ought-whenever, nobody complains, so we continue to do so." One of those 'if it ain't broke, don't fix it' kind of things. I, for one, would like to hear from a ballistician or firearms engineer on this subject of twist rates. Much of it makes little sense to me.

[jandbn]

9.3X62AL,

I don't really care about the calculated twist rate because I can depend on everybody here to get "real world" examples of what works or don't work. It is just kind of strange that you have all those the long barrel folk that seem pretty dependent on twist calculation for their Bergers and A-MAXs and MatchKings when they order the barrel to build their one-holers. You would think that this day and age, somebody would have developed a twist formula for handgun length barrels. I have been away from shooting/reloading for over 20 years and I am finally ready and able to get back in the "bang" of things. But I would of thought by now that there would be there would have been a formula floating around somewhere. I just don't make much sense to for a revolver's twist to be around twice that of what the calculated twist is for rifles. I will take the all experience and knowledge here anyday!!

[S.R.Custom]

...I would of thought by now that there would be there would have been a formula floating around somewhere. I just don't make much sense to for a revolver's twist to be around twice that of what the calculated twist is for rifles...

Here's one for ya...

Suppose you were chambering a .44 Spl round in your Ruger SBH, and the characteristics of that .44 spl round were such that the bullet length was 0.790" --like the 250 gr. RCBS Keith bullet in my hand right now-- and the velocity was a typical old school .44 spl velocity of about 750 fps. Plug those numbers into this Greenhill calculator...

http://kwk.us/twist.html

...and see what pops out. While you're there, scroll down and read the bit about velocity: If you have to adjust the "constant" from 150 to 180 to compensate for really fast velocities, it makes sense that you would have to lower it for slower ones. This formula does that.

[edit] Here's another one that validates the 1:20 SBH twist. Again, consider our .44 Spl loaded with a Keith bullet to 750 fps...

http://www.uslink.net/~tom1/index.htm (click on "Calculate Optimum Twist Rate" and scroll down.)

Just out of curiosity, I plugged in my custom .444 Marlin boolit, a 405 gr unit that measures 1.125" in length. In my Winchester, it gets tossed out at 1800 FPS. The online calculator indicates a happy twist rate of 1:24...

[Lloyd Smale]

your loosing track of one important fact. Cast bullets are used in big game hunting because they penetrate the best of any bullet. But theres a limit to the velocity you can use to get this great penetration. We done a pile of testing and about 13-1400 fps is the limit to what most cast bullets can be shot at before they start deforming on impact. If a bullet deforms in any way on impact penetration will suffer dramaticaly. So in the case of a 44 mag a guy with a good gun can push a 300 grain to these velocity levels. To push a 250 to 1500 is counter productive. All its doing is increasing recoil and decreasing penetration. I get guys all the time claiming they use a certain load or gun because it shoots flatter. THe 454s and 460s are good examples. They may shoot a tad flatter out past a 100 yards just like using a light fast bullet in the 44s will shoot a bit flatter but past a 100 yards no handgun is flat shooting and they all demand you learn where your load hits so to me it doesnt matter if it hits 10 inches low or 15 inches low. I have to compensate anyway. I also beleive theres not a dozen handgunners in the US that have any bussiness shooting live game past a 100 yards with even a scoped revolver. Theres just to many variables in the field when hunting that can cause a blown shot and a wounded animal. So the least important thing to me when working up a hunting load for a handgun is trajectory and if i was going to shoot a deer or bear or pig at 200 yards id rather have the heavier bullet to insure deep penetration then a couple inches of trajectory i can conpensate for myself.. to me where the 44 really comes into its own is with a 300 grain bullet at about 1200fps. That load will take any game animal on earth and has taken them. It is mild recoiling, It will break big bone and still penetrate. It will shoot accurately and shoot flat enough for any work im going to do with a handgun.
I never said any different. What I said was --from the SBH-- the 300 grain bullet starts so much slower than the 250 grain bullet INITIALLY, that it doesn't make much sense to fool around with anything heavier. To wit:

From my 7.5" SBH and a 250 gr LSWC, I can shake 1503 FPS (mean) as measured at 20' with an Oehler 35P. The most I can coax out of the 300 gr LSWC, on the other hand, is 1217 fps. Any more, and the primer pockets start to loosen. (And both of those figures, incidentally, surpass just about any published numbers for 'safe' loads.)

If we take that data and apply it to the ballistic tables found in Sierra's 3rd, we see that it takes the 300 gr bullet 250 yards to "catch up" to the 250 grain bullet in retained energy and momentum. And if we're smart and the purpose of our shooting is bullets-on-game out past 250 yards, we're not using the original poster's open-sighted Ruger SBH, are we? Anyway, my point in my previous post was that the twist of the Ruger SBH is just fine for anything you're likely to use it for.



What's your problem? Did I say something that offended you?

[44man]

Lloyd, you said it better then I could.
One reason for the short barrel to need a faster twist is the velocity limit. If a boolit needs a certain RPM range to be stable and accurate at all ranges, what comes out of the short barrel still needs to be close to what comes out of a rifle.
The faster twist allows a lower velocity to be used along with lower pressures and lets one find the sweet spot without over loading.
Yet, if you want to push the boolit some more from the revolver, it will still be stable when too slow of a twist is just starting to get stable.
That is why the .45 Ruger has a 1 in 16" because it is a slow round to start with. Go to a rifle and 1 in 20" to 1 in 25" would work better but to go to 1 in 38" makes it so you can't shoot the boolit fast enough for long range stability due to case capacity and pressures.
Marlin got so many complaints about the .444 because even it would not spin up a heavy boolit so they changed it to a 1 in 20". But the .44 mag just can't get anywhere near the velocity needed yet they left it 1 in 38". That makes it a light boolit shooter and maybe a round ball is better! :mrgreen:
Yes, some pencil neck at a desk used straight Greenhill for the guns.
Now there is much talk about changing figures and you can make it match about anything you want to by starting with the twist you have and working backwards so you can prove it is right. Are you proving anything? Will it work for all calibers? NO, best to just dump Greenhill instead of making it match your gun.
The proof is what the gun actually does and I would never give up the fast BFR twists for anything. When a revolver can whip the pants off of a rifle at 500 meters and shoot a 5/16" group at 50, don't even suggest it to me! :drinks:
Supermag, if you work at it, you can prove Greenhill for my 1 in 14" twist! :bigsmyl2:

[alamogunr]

I've been following this thread with interest although I don't usually think this deep. Before I list some articles I'm aware of, I need to state that I don't understand half of what is presented. I am more mathematically challenged than most who have an engineering degree.

Precision Shooting magazine has had several articles recently concerning twist. The subject deals with twist in rifles, not handguns. I don't have a scanner, so I can't send them to anyone, but if you can find these articles, they might shed some light. I say "might" because, as I said, I don't understand half of what is presented.

Precision Shooting: "New Twist Rule": Part 1 &2, February,2008 and March, 2008

Precision Shooting: "How Good are Simple Rules For Estimating Rifling Twist": June, 2009

John
W.TN

[44man]

I've been following this thread with interest although I don't usually think this deep. Before I list some articles I'm aware of, I need to state that I don't understand half of what is presented. I am more mathematically challenged than most who have an engineering degree.

Precision Shooting magazine has had several articles recently concerning twist. The subject deals with twist in rifles, not handguns. I don't have a scanner, so I can't send them to anyone, but if you can find these articles, they might shed some light. I say "might" because, as I said, I don't understand half of what is presented.

Precision Shooting: "New Twist Rule": Part 1 &2, February,2008 and March, 2008

Precision Shooting: "How Good are Simple Rules For Estimating Rifling Twist": June, 2009

John
W.TN
You have joined my club! :bigsmyl2: Math sucks. Some have it and some don't, I sure don't! Deep thinking other then the mechanical stuff never happens here.
Is there a link to read that stuff?

[felix]

Again, folks, they are talking NO FREEBORE! ... felix

[44man]

Again, folks, they are talking NO FREEBORE! ... felix
Glad you said that but it would still be a good read to see what changes are being made.
Might be something to debunk! :mrgreen::mrgreen:

[StarMetal]

The reason, Joe, is accelerating the boolit's rotation. Wider projectiles are progressively harder to do without stripping. ... felix

Felix and all,

Here's the answer I got back from my friend at Lothar Walther:

None of those barrels we did had gain twist. Not even all the ones they did had it. Marketing hype and truth are mutually exclusive. A .452 dia. bullet spins in a revolver barrel just the same way a 32 357 or 44 does. The barrels groove was 450 and the bullet was 452 so the grip was very strong. This is what led to the super high hydraulic deformation inside the barrel.

I'm a little confused by it, the part on a 450 groove and using a 452 bullet. Yeah I know he said for a tighter grip. Now a friend of mine has a 460 Smith and if I recall he said his has normal rifling. I just emailed him to find out for sure.

Joe

[44man]

Felix and all,

Here's the answer I got back from my friend at Lothar Walther:

None of those barrels we did had gain twist. Not even all the ones they did had it. Marketing hype and truth are mutually exclusive. A .452 dia. bullet spins in a revolver barrel just the same way a 32 357 or 44 does. The barrels groove was 450 and the bullet was 452 so the grip was very strong. This is what led to the super high hydraulic deformation inside the barrel.

I'm a little confused by it, the part on a 450 groove and using a 452 bullet. Yeah I know he said for a tighter grip. Now a friend of mine has a 460 Smith and if I recall he said his has normal rifling. I just emailed him to find out for sure.

Joe
Just go to the S&W site, it tells you in black and white that the .460 has a gain twist.

[felix]

Nothing wrong with gain twist, as long as it is extremely slight and used primarily for keeping constant tension on the groove cutter. Just what is the difference between initiation and termination on that 460 barrel? ... felix

[StarMetal]

Just go to the S&W site, it tells you in black and white that the .460 has a gain twist.

Here's what he said about that Felix: Marketing hype and truth are mutually exclusive.

Joe

[alamogunr]

Fraid not! The website for Precision Shooting only has the feature article for the three most recent issues. The magazine is fairly specialized toward bench rest shooting. I have subscribed to it for several years because of the odd ball articles they include each month. For example, the June,2009 issue has an article titled "Shooting the Grease Gun", featuring the WWII stamped sheet metal submachine gun.

If I can find someone that has a scanner, I will try to get a copy for you.
John
W.TN

This in reply to 44 Man's query about a link.

[felix]

That, of course, Joe, depends on the folks doing either. Some salemen talk about attributes that have no effect on the application on hand, and some engineers talk about the superiority of their equipment in making the said product. All what we want on this board are guns WE can shoot using the cheapest components we can purchase or make. Completely different goals than the BR application, where cost and effort together is of no concern. ... felix

[Bass Ackward]

The real thing to take away with cast usage is the the faster the twist rate that you "have to" use because of choices you make in the launching system whether that be handgun or rifle, the narrower the accuracy window is going to be. ESPECIALLY if you want to push the envelope.

And from that, the narrower the options available to the reloader to work to fall within that window. That means everything from bullet weight, to design, to lube, to hardness, to everything.

Anyone that has ever fooled with cast very long learns very quickly that multiple reloading options makes for more accuracy choices .... and a more fun project.

[44man]

The real thing to take away with cast usage is the the faster the twist rate that you "have to" use because of choices you make in the launching system whether that be handgun or rifle, the narrower the accuracy window is going to be. ESPECIALLY if you want to push the envelope.

And from that, the narrower the options available to the reloader to work to fall within that window. That means everything from bullet weight, to design, to lube, to hardness, to everything.

Anyone that has ever fooled with cast very long learns very quickly that multiple reloading options makes for more accuracy choices .... and a more fun project.
I have not found that true in the revolver. A faster twist will DOUBLE boolit choice and weights I can use. Only the lighter boolits will not perform. Too slow of a twist severely limits boolit choice and you can be stuck with light for caliber boolits. Of course the gun will still "go bang" with whatever you put in it.
You have to determine what accuracy is of course. Take My .475 with a 350 gr boolit. It will do 2" to 3" at 50 yards and most guys would be tickled pink. Many jump up and down and wave their arms with 2" at 25 yards! :confused:
With a slower twist of 1 in 18" it gets very, very hard to get super accuracy as you pass 400 gr boolits, some have done it but not many. Most use over loads to do it. This twist loves 350 gr and will do 1" or less.
Mine does not start to shoot until I reach 400 gr and from there to 460 gr, it will hold sub 1" at 50 yards. It might even do it with heavier boolits but I don't have any to try.
I spent half my life shooting long range rifles with jacketed bullets and in every case, a faster twist was easier to work with but if I shot only to 100 yards or only used light bullets I would want a slower twist.
Twist rate still has to be determined by the use and distance you want your gun for. You can't say a slower twist is better anymore then I can say a faster one is better because everyone is doing something different.
But you can't ignore the importance of twist depending on usage.
For what I do, I want a faster twist. A slow twist might be perfect for you. You can't apply what you do for a fella that wants to shoot a heavy boolit for hunting and I can't apply what I do for a fella that wants a light boolit target load.

[jandbn]

Can anybody else chime in with their experience either similar or opposite of to 44Man's last post? I need more to stuff into the gray matter.:killingpc


Suppose you were chambering a .44 Spl round in your Ruger SBH, and the characteristics of that .44 spl round were such that the bullet length was 0.790" --like the 250 gr. RCBS Keith bullet in my hand right now-- and the velocity was a typical old school .44 spl velocity of about 750 fps. Plug those numbers into this Greenhill calculator...

http://kwk.us/twist.html

...and see what pops out. While you're there, scroll down and read the bit about velocity: If you have to adjust the "constant" from 150 to 180 to compensate for really fast velocities, it makes sense that you would have to lower it for slower ones. This formula does that.

[edit] Here's another one that validates the 1:20 SBH twist. Again, consider our .44 Spl loaded with a Keith bullet to 750 fps...

http://www.uslink.net/~tom1/index.htm (click on "Calculate Optimum Twist Rate" and scroll down.)


SuperMag,

I guess maybe I am guilty of not delving deep enough into optimum bullets for a given twist rate. Your examples provided data for me to try in the formulas that I didn't consider. In my first post, I had used heavy for caliber boolits in the calculations. As I mentioned before, I will take all the knowledge and experience here any day rather than rely on calculations. But… I do have this “problem” of not leaving well enough alone. So I proceeded to take a closer look at the formulas.

After crunching numbers and pondering the use of “adjusting the constant”, my initial assumption (NOT conclusion) is that manufacturers are using twist rates to “cover all the bases”. What I mean is they use twist rates to stabilize worst-case load combinations. Others have said this in so many words, but I guess I’m deaf in one ear and can’t hear with the other. Based on my assumption, then longer boolits and more velocity means “over-stabilization”.

The long barrel bench rest folks are concerned with their twist rates in that they “want” the minimum twist needed to stabilize their chosen bullet. From what I can gather so for with practical handgun hunting/shooting distances, over-stabilizing the boolit has minimal affect that probably can’t be measured. My idea of the effective hunting range of a revolver is around 50 yards. My choice of a 45 Colt at 1200 fps is all I need and probably then some for hunting where I do and thus the reasoning behind that combination. I don’t pretend to know what difference over-stabilization in a handgun has in small bore to large bore and in between, but I think it would be a moot point. (44Man may disagree with over-stabilization as he shoots his revolvers for accuracy. At my age, I’d almost give my left nut to be able to shoot groups 44Man has posted.:p)

My quest now is for self-information. I would like to see a graph or pivot table that would plot minimum stabilization. I am not a mathematician by any stretch, nor do I understand gyroscopic science like benchrest crowd. What I do understand is a given handgun with a specific twist shooting a boolit of a specific length (and weight), must exit the barrel at a specific diameter where velocity can be measured by a chronograph. Now if I could just plot RPM for length and caliber. If I can accomplish that, it might give a visual as to any correlation. It wouldn’t be much use in real world application but I would get the satisfaction of doing it because I can (I hope).

Below is an illustration for those that may read this thread and have not considered a twist formula, is a comparison of your first example load and a heavy for caliber load. I used the twist calculator on http://kwk.us/twist.html. Miller’s Twist Calculator gives very similar results. (Maximum Specific Gravity (SG) value is 11.3 for lead. I used 11.2 as an arbitrary number for a lighter lead alloy boolits.) This comparison will illustrate what happens in regards to over-stabilization as velocity (RPM) is increased. (I am not picking on Ruger at all. It is just that twist is readily available on their website.)

44 Special (Ruger with 20 twist)
Weight: 250 grain
Length: .760”
Diameter exiting Muzzle: .429”
Velocity: 750 fps
SG: 11.2
Calculated Twist 24 (SG of 10.9 for J-word = 23)

44 Mag (Ruger with 20 twist)
Weight: 250 grain
Length: .760”
Diameter exiting Muzzle: .429”
Velocity: 1500 fps (your load in your SBH)
SG: 11.2
Calculated Twist 33
---------------------------------------------------
Other comparisons:

38 Special (Ruger with 18 ¾ twist)
Weight: 158 grain
Length: .630”
Diameter exiting Muzzle: .356”
Velocity: 750 fps
Length: .630”
SG: 11.2
Calculated Twist 19.5

357 Mag (Ruger with 18 ¾ twist)
Weight: 158 grain
Length: .630”
Diameter exiting Muzzle: .356”
Velocity: 1250 fps
SG: 11.2
Calculated Twist 25
---------------------------------------------------
45 Colt (Ruger with 16 twist)
Weight: 260 grain
Length: .670”
Diameter exiting Muzzle: .451”
Velocity: 750 fps
SG: 11.2
Calculated Twist 29

45 Colt (Ruger with 16 twist)
Weight: 260 grain
Length: .670”
Diameter exiting Muzzle: .451”
Velocity: 1200 fps
SG: 11.2
Calculated Twist 37
---------------------------------------------------

[gunsbrad]

Folks, this is a very worthy discussion and I just want to add this.

Benchrest some bench rest shooters are worried about overstabilization and try to get a minimum twist to shoot at the given range. For instance .22 rimfire 50 yard benchrest competitors are only concerned with accuracy at 50yds. They don't care if it destabilizes at 75 or 100. 50 yds is where the trophy is. I personally want my .22s to be accurate much farther, but I play a different game. All br shooters don't buy into the minimum stabilization theory.

Greenhill's formula was an attempt to give an easy to find minimum twist, not optimum. He never claimed it was optimum.

Brad Hurt

[jandbn]

Brad,

I guess I should have been more specific in my comments about bench rest shooters. I should have said "some", not imply ALL. You are correct about the Greenhill formula. My original thought was to "find" optimum weight with a known twist. All things considered, RPM seems to be the place to start looking and build off of that.

[felix]

Really, you can say "ALL", Jan. One deviates in that sport for experimentation only, such as for improvement in say, certain ambient conditions such as shooting through severe gusts. I can remember "unique" barrels were used for certain benches at certain matches by a few diehards. If these folks won consistently enough, everyone would switch to that configuration within a year or two for all matches. ... felix

[jandbn]

Felix,

I appoligize if I don't have my "poop in a group." I am still playing catch-up from 20+ years of being away from shooting and hunting. When I was shooting and hunting way back when, all I knew was more ft lbs and velocity was better. Now that I am some what older and wiser and have boned up a little on real world experience from others, I know I have quite a learning curve to overcome. My hope in posting was to get opinions/help from everyone which in turn, helps to "re-educate" me properly. I am sure I WILL make mistakes here and there, but unlike other forums, the vast majority of CB members are congenial folks that are willing to help rather than ridicule. There are many on CB that have my respect and I hope to learn more from the experience here.

[Lloyd Smale]

I can relate my loading experinces with 45 colt rugers to what 44man said, It never made sense to me that they went with a faster twist (1-16) then they did with the 44s. I know they were meant to shoot bullets realitivly slow but so is the 44 specail and they get a 1-20 twist. It is nie on impossible to find a bullet under 280 grain that will shoot well at long distantances in a ruger 45 colt. It cant be that the bullet doesnt get enough spin as the twist is faster. It has to be a matter spinning those bullets to fast. A combination of that and if you look closely at your 45 ruger the rifling lands and groves are even shapped a bit differntly then there barrels in 44 and are a bit shallower. Im sure what happens is bullets are spun so fast that they are stripping through the rifling to some extend. Im sure someone will jump in and say there 45 shoots well. For one thing im talking long range. Over 200 yards. Ive got some decent groups at 25 and 50 with them but even then a good load seems about 10 times harder to find for a ruger 45 then a ruger 44. I cant for the life of me figure why ruger does this. Again i guess its because theres for the most part a bunch of yuppy bean counters running most of these gun manufactures these days and for the most part we are an exception not the rule. Most people are happy shooting a box of factory ammo once or twice a year and are happy if they can hit a coffee can at 10 paces.
I have not found that true in the revolver. A faster twist will DOUBLE boolit choice and weights I can use. Only the lighter boolits will not perform. Too slow of a twist severely limits boolit choice and you can be stuck with light for caliber boolits. Of course the gun will still "go bang" with whatever you put in it.
You have to determine what accuracy is of course. Take My .475 with a 350 gr boolit. It will do 2" to 3" at 50 yards and most guys would be tickled pink. Many jump up and down and wave their arms with 2" at 25 yards! :confused:
With a slower twist of 1 in 18" it gets very, very hard to get super accuracy as you pass 400 gr boolits, some have done it but not many. Most use over loads to do it. This twist loves 350 gr and will do 1" or less.
Mine does not start to shoot until I reach 400 gr and from there to 460 gr, it will hold sub 1" at 50 yards. It might even do it with heavier boolits but I don't have any to try.
I spent half my life shooting long range rifles with jacketed bullets and in every case, a faster twist was easier to work with but if I shot only to 100 yards or only used light bullets I would want a slower twist.
Twist rate still has to be determined by the use and distance you want your gun for. You can't say a slower twist is better anymore then I can say a faster one is better because everyone is doing something different.
But you can't ignore the importance of twist depending on usage.
For what I do, I want a faster twist. A slow twist might be perfect for you. You can't apply what you do for a fella that wants to shoot a heavy boolit for hunting and I can't apply what I do for a fella that wants a light boolit target load.

[44man]

Lloyd, I suppose the .45 would do well with a 1 in 20" and would probably work better with lighter boolits because they are short for diameter. I sure would not go slower though.
On the other side of the coin is my Lyman boolit that gets rifling engraved almost to the meplat. Depending on alloy it drops from 343 to 347 gr. It can't be driven fast, doing 1167 fps at the most accurate point. This benefits from the faster twist because of the lower velocity and does not skid the rifling beyond a tiny bit at the front. This boolit is .855" long and is engraved about .750".
I have killed deer in their tracks to just beyond 100 yards and on occasion have shot 1" groups at 75 yards.
Since it is a Vaquero, the sights beat me for long range and boolit drop is out of sight so I have not shot it as far as my other revolvers.
The point is that the gun does exactly what I want it to. Anyway, it is back to what you want to do and you are correct that a little slower twist will work better for a lighter boolit.
Now I do have the 255 gr Lee and with a light load of 7 gr of Unique, it is a can buster supreme out to 50 yards. I never tried to take it to a heavy load of slow powder because I hunt with the heavier boolits but I don't think it would do so good. I feel Ruger rifled it for normal Colt pressures with factory loads. Lighter boolits shot slow should benefit from the faster twist but if you want to jack them up you need a little slower.
Actually, the faster twist should be ideal for a cowboy action shooter with those zero recoil loads. It is the only way to get some spin on them. If you want to hunt, just use a heavy boolit, the LBT 335 gr shoots super too.
Now Jandbn shows calculated twist rates and I can assure you, none will work. If you found something to shoot, it will be the ONLY thing you can shoot. After two or three years testing you would finally give up. [smilie=l:

[felix]

Lloyd, the 45 surely can gain stability if they got rid of those shallow lands. ... felix

[felix]

Jan, no apology needed for anything. The BR crowd is interested in only one thing and that is how well they can shoot under extreme stress (weather, mainly). The guns have little to do with it because they are the "same" except for maybe personal balance in the recoil arena. Many different stock differences, for example. ... felix

[44man]

Felix, doesn't look that bad!

[S.R.Custom]

...My quest now is for self-information. I would like to see a graph or pivot table that would plot minimum stabilization...

Let us know when you're done. :mrgreen:

Seriously, tho, I would imagine this would be as difficult as finding a precise ballistic coeficient. What with the various bullet lengths, densities, nose profiles, etc. to consider, determining an exact optimum spin would be damn-near impossible; it's kind of tough to measure the air pressures around a particular bullet as it cuts through the air, so we really don't have any idea of what's really going on. It's pretty tough to come up with an accurate mathematical model in the general absence of data.

Greenhill's formula was hatched at a point in time where all bullets left their respective barrels at pretty much the same velocity (owing to the pressure limitations of black powder), and all bullets looked pretty much the same (round nose, 1-3 calibers long). The formula was a general mathematical guide, and at the time, worked reasonably well. Things now are a bit more complicated , no?

[jandbn]

SuperMag,

You pretty much hit the nail on the head. To say the least it is complicated and I am more than likely biting off more than I can chew. In practice, Excel works just peachy. But my head is already spinning :veryconfu and until it slows down, Excel won't be of much use. I don't have ballistic software that cost $ ‘cause I'm cheap. So if I'm able, I'll have to rely on my ability with math (which leaves a lot to be desired).

Maybe I haven't searched enough, but I have been unable to locate equations using RPM or twist rates plotted on an X or Y axis. So to start with if I can grasp enough to make things somewhat logical, I would "generalize" like the Greenhill type formulas. My thought for now is to "reverse engineer" (for lack of a better term) the common twist rate formulas and plot based on RPM. My fuzzy logic at this point is a boolit needs so many RPM for its length to remain stable from muzzle to impact. RPM can be calculated with the known barrel twist (with NO bullet stripping at the muzzle) and muzzle velocity. What I hope to see is a correlation on a plot line for RPM calculated on the other twist formula variables. Twist rate is based on basic variables, so maybe I can eek out an optimum bullet per RPM?

I’d start with a single cartridge, plot a graph, and then compare the results to other cartridges and "see" if anything shakes out. Also, if there is a plot line for RPM, then see if or how that correlation fits “on top” of current twist formulas. To keep “life” simple as possible, flowfield would need to be ignored. There are already enough numbers to contend with! I realize the mechanics of the flowfield are part of the total equation, but I don't really want spend time getting a "college degree" educating myself just for a hobby... unless a whole bunch of light bulbs turn on all at once. But I really, really doubt juice will flow that freely. I'd much rather be pressing a trigger than keys a keyboard!! Although… there are those cold MN winters when there's not much to do...

Ten dollars to a doughnut says what ever I end up with won’t even come close to real world experience and results! :bigsmyl2: