Twist rate and bullet length

[Jshorter]

I apologize in advance for the newbie question. I’ve been doing some more reading about long range shooting with 45 cal. There seems to be a lot of debate and opinions on 1 in 18 vs 1 in 20, 1 in 22, etc. Overall it seems that the 1:18 is preferred, and that’s what is winning competitions. My question is if bullet length is relative to the twist rate then why wouldn’t a 1:20 twist with the correct length bullet shoot as good as the 1:18 with the correct length bullet at say 1000 yards? The 1:18 stabilizes a longer bullet better than 1:20, so are the longer bullets in general better for long range?

 

[Jshorter]

Also if anyone could point me to some good sources on this topic that would be much appreciated.

 

[ElDiablo]

I think in .45, the 275 gr to 350 gr bullets with high BCs tend to be good long range choices. The 1:18 - 1:20 twist seems to shoot those bullets very well. Short range hunting (100 yards) you will not see any appreciable difference but at long range (say 300+ yards) the 1:18 is a very versatile choice.

 

[bronko220002]

Bison bullets has a great bullet stabilization calculator. I just found it posted by another member either here or on the sister site.

 

[ElDiablo]

Yes, here’s Bison’s:

https://bisonballistics.com/calculators/stability
Here’s another by JBM:

https://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi

 

[ElDiablo]

According to the Hornady ballisticians, the commonly used Miller stability formula is a simple calculator that may be off up to 20%. Gyroscopic stability at above 1.0 is the general rule. In the 1.0 to about 1.1 or 1.2 - you may see poor accuracy. Rule of thumb - must be > 1.4.

 

[Jshorter]

Yes, here’s Bison’s:

https://bisonballistics.com/calculators/stability
Here’s another by JBM:

https://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi

Thank you! I haven’t seen this yet so I’ll check it out

 

[X-ring]

I apologize in advance for the newbie question. I’ve been doing some more reading about long range shooting with 45 cal. There seems to be a lot of debate and opinions on 1 in 18 vs 1 in 20, 1 in 22, etc. Overall it seems that the 1:18 is preferred, and that’s what is winning competitions. My question is if bullet length is relative to the twist rate then why wouldn’t a 1:20 twist with the correct length bullet shoot as good as the 1:18 with the correct length bullet at say 1000 yards? The 1:18 stabilizes a longer bullet better than 1:20, so are the longer bullets in general better for long range?

In .45 cal. 1:18 is the most common rate of twist for mid-long range shooting with m/l or B.P. ctg. rifles. If you intend to shoot long range, you'll need bullets of 500 grains or more. Longer bullets are better for long range. Don't over think things. Use what works. If the 1:18 is preferred and what is winning, what is there to debate? X

 

[Mnt monkey]

I realize the 18 twist is the choice for the long distance big lead shooters ,but it's also the best option for the hunter,, all of my 18 twist barrels shoot the light bullets that those that are looking at the 20 twists want to be able to shoot, in particular the lighter 40 cal bullets in the light blue sabot,,, as for bullet size to bore anything from a 250 to a 400 plus with a jacket and the 18 of course will do lead even bigger. Having so many bullets downrange the last years the only way I would build a 20 and then forgive my sarcasm would be if I wanted to limit myself if I want all the bullet choices I can have in my rifle and better performance even in the lighter bullets it's hands down the 18,,, my position is from shooting 3 to 4 days a week, as I mentioned in another thread I have for the most part ignored the barrel twist bullet length charts and just sit down and shot myself ,, I think many see the 18 as too much twist, and you can get too much spin on lead bullets, and sabots,even with a jacketed bullet,, however to me the 18 is at that Perfect Limit it gives me bullet choices, that the 20 does not and with the bullets that I wanted to shoot in the 20 in my experience the 18 does just as good if not slightly better again I'm talking statistically with multiple rifles not just one pet rifle in 20 for one pet rifle in 18.

 

[ENCORE50A]

...................... Overall it seems that the 1:18 is preferred, and that’s what is winning competitions. My question is if bullet length is relative to the twist rate then why wouldn’t a 1:20 twist with the correct length bullet shoot as good as the 1:18 with the correct length bullet at say 1000 yards? The 1:18 stabilizes a longer bullet better than 1:20, so are the longer bullets in general better for long range?

Only considering 45cal..............

There's an awful lot involved in LONG RANGE shooting, especially 1,000yds. To my knowledge, there's only 4 of us on this site shooting MODERN INLINES to 1,000yds. Quite frankly, all 4 of us are still learning.
The potential problems with a 1:20, even shooting a great bullet for that twist rate, would be yes, length and its BC. Heavier and longer bullets are the rule. 275gr and 300gr bullets are very poor choices for shooting 1,000yds. Bullets of at least 325grs with very high BC's, even better at 350grs, work well at 1,000yds out of a 1:19 twist and the 1:18's.
Propellant charges in competitions is limited to 120grs VOLUME of BH209, giving approximate velocities of around 2,180fps +/-. Bullets will go sub-sonic at approximately 800yds.

This Arrowhead 350gr XLD has won 2 of the 3 long range matches of 800, 900 and 1,000yds.




Although a quality bullet, the Pittman Accumax 275gr bullet, it is not a LONG range bullet and wouldn't be used in competition.




This is a Fury 300gr. It is an outstanding hunting bullet but, it doesn't stabilize well beyond 400yds.

 

[Jshorter]

In .45 cal. 1:18 is the most common rate of twist for mid-long range shooting with m/l or B.P. ctg. rifles. If you intend to shoot long range, you'll need bullets of 500 grains or more. Longer bullets are better for long range. Don't over think things. Use what works. If the 1:18 is preferred and what is winning, what is there to debate? X

This makes more sense now knowing that longer bullets are better for long range, and the 1:18 stabilizes a longer bullet better.

 

[X-ring]

This makes more sense now knowing that longer bullets are better for long range, and the 1:18 stabilizes a longer bullet better.

Were you thinking about using a traditional M/L, a B.P.Ctg. or a modern inline muzzleloader for long range? X

 

[Sarge]

Random thoughts:
Short answer is yes, longer is better. Lots of factors come into play for ultimate accuracy not even counting the ones we can’t control.
The velocity plays a major factor in bullet stabilization. The same bullet can be stabilized with different twist rates depending on types of powder used generating higher velocity(BP v BH v Smokeless). For example, a particular bullet may stabilize in 18 twist using BP, 20 twist using BH, and 22 twist using smokeless.

 

[Jshorter]

Were you thinking about using a traditional M/L, a B.P.Ctg. or a modern inline muzzleloader for long range? X

Traditional, I figured the twist rate and bullet length concept would be same across the board?

 

[Sarge]

Concept is the same, just not necessarily interchangeable, but can have overlap.

 

[X-ring]

Traditional, I figured the twist rate and bullet length concept would be same across the board?

It is. If you are going traditional, then you'll be shooting big lead bullets such as the Lyman 535 gr postell, a money bullet style [both are grease groove] or a paper patch bullet. The 1:18 twist will shoot any of these well when you find the right load. Just some random suggestions. Get a Soule type rear sight, a Hadley eyecup and an aperture front sight with spirit level. Use 1 1/2 or 2f Swiss whichever gives better accuracy. X

 

[Jshorter]

It is. If you are going traditional, then you'll be shooting big lead bullets such as the Lyman 535 gr postell, a money bullet style [both are grease groove] or a paper patch bullet. The 1:18 twist will shoot any of these well when you find the right load. Just some random suggestions. Get a Soule type rear sight, a Hadley eyecup and an aperture front sight with spirit level. Use 1 1/2 or 2f Swiss whichever gives better accuracy. X

What’s the heaviest you would shoot in a 1:18 or 1:20? Thank you for the sight suggestions; that’s probably the route I’ll go.

 

[X-ring]

What’s the heaviest you would shoot in a 1:18 or 1:20? Thank you for the sight suggestions; that’s probably the route I’ll go.

All my .45's are 1:18. I shoot the 535gr. Lyman postell in my Ctg. rifles and a 535 gr postell and a 540 gr. paper patch in my Gibbs. Shooting a heavier bullet would gain nothing but more recoil. Check Buffalo arms website for a good selection of .45 bullets, moulds, and sights. X

 

[Bruce in WV]

There is an interesting entry on the Pedersoli site buried in the blog entry about one of their rifles. The last sentence is relevant:

"The rifling twist of Pedersoli's .50 CALIBER RB-ML RIFLE bore is a snappy 1-in-24 twist ... while every other production run in-line .50 caliber rifle comes with a 1-in-28 rifling twist. So ... What Makes The 1-in-24 Twist So Advanced? At this point, let's just say that it has long been my contention that we've "outgrown" the 1-in-28 rifling twist. William "Tony" Knight and I came up with that twist back when both the "ultra modern" in-line rifles and saboted bullet concepts were just getting off the ground, during the mid to late 1980's. Ever since, the 1-in-28 twist has become the in-line rifle "Industry Standard" - a standard that was entirely based on stabilizing fairly short .44 and .45 caliber handgun bullets ... using a plastic sabot ... out of a .50 caliber bore."

 

[Ninering62]

There is an interesting entry on the Pedersoli site buried in the blog entry about one of their rifles. The last sentence is relevant:

"The rifling twist of Pedersoli's .50 CALIBER RB-ML RIFLE bore is a snappy 1-in-24 twist ... while every other production run in-line .50 caliber rifle comes with a 1-in-28 rifling twist. So ... What Makes The 1-in-24 Twist So Advanced? At this point, let's just say that it has long been my contention that we've "outgrown" the 1-in-28 rifling twist. William "Tony" Knight and I came up with that twist back when both the "ultra modern" in-line rifles and saboted bullet concepts were just getting off the ground, during the mid to late 1980's. Ever since, the 1-in-28 twist has become the in-line rifle "Industry Standard" - a standard that was entirely based on stabilizing fairly short .44 and .45 caliber handgun bullets ... using a plastic sabot ... out of a .50 caliber bore."

I have a really sweet .50 1:24, as cool & beautiful as it is, if it were another 1:28 I wouldn't have it right now.