Twist rate for a .45 caliber

[moleeyes36]

I'm about to order a .45 caliber barrel from FCI for an under hammer project I want to do this fall.  In all the guns of various calibers I've owned over the years I've never had a .45 caliber rifle.  The various makers use different twist rates for .45 caliber barrels (Colerain 1:48, Green Mtn. 1:60, Rice 1:66, etc.). 

This is going to be a barrel for round ball use and I need to specify the twist rate I want when I order the barrel.  Having no experience with the caliber I don't know what the optimum twist rate for a round ball barrel in .45 caliber should be.  Is there a generally accepted "standard" twist rate for this caliber?  Thanks.

Mole Eyes

[smylee grouch]

How fast do you want to push the ball?  Faster ball usualy works better with a slower twist. Slower than 1-48 if you realy zip it out there. IMHO

[rhbrink]

 A 60 or 66 inch twist would suit me I have owned both and they all shoot very well. Might ask the barrel maker what his favorite is?

RB

[Hungry Horse]

The best shooting rifle in .45, I have ever shot, was made from one of the old Dixie barrels, that was designed to convert a trapdoor Springfield into a muzzleloader. The rate of twist was 1 in 56". One of the modern custom barrel makers mentioned in an article in one of the muzzleloading oriented magazines that this was the ideal twist for a .45, and I believe him.

                         Hungry Horse

[Don Getz]

I have tallked about a 45 that I had, built it with a 1/56 twist.   Had a 4 power weaver scope on it, would virtually shoot a
slightly enlarged hole at 50 yards.  I shot a .445 ball with .018 OxYoke wonder patch.   It would shoot great with 40 to 60 grains of Goex FFF...........Don

[Long John]

I would use either a 1 in 60 or 1 in 66 twist, especially if you want to shoot at the upper end of the velocity spectrum.  In my experience, slow twists with radius groove rifling will shoot higher charges with faster velocities and less fouling than faster twists.

Best Regards,

John Cholin

[moleeyes36]

Thanks for all the input.  I've had a lot of experience with .40 and .50 caliber rifles so I expected something in the neighborhood of 1:60 would work well in a .45 for most uses since it's in between the 1:48 in a .40 and the 1:70 I prefer in a .50.

Mole Eyes

[galamb]

My first 45 was 1:56, the one I'm building now is 1:66.

I believe if you use the Greenhill formula = 150 X diameter squared/length of the projectile.
(150 x (.45 X .45)/.45 for a roundball) = 1:67.5

If you use the modified Greenhill it is cal x 1.25 = .45 x 1.25 = 1:56

So toss a coin unless you plan on shooting conicals 

[greybeard]

Many moons ago I had a 1 in 70  barrel 36" .  One of the best ever with 70 grains ffg.
        bob

[eddillon]

According to the Greenhill formula the twist should be 1:67.3 so I guess that 1:66 is pretty dang close.

[RichG]

I have an old Sharon button rifled 45 barrel with a 1-72 twist and very shallow rifling. Any load I've tried in it from 35-70 grs. 3f shoots better than I can. 70 grs. 3f gets just over 2000fps.
1in 48 might be a little fast but anything slower should work great. just work up a load your barrel likes.

[gard72977]

I had a H/A target 45 with the heavy barrel. It had a 1/66 twist and shoot great. I wish I had not got rid of it!! It shot well with light charges down to as low as 40gr.

[moleeyes36]

My first 45 was 1:56, the one I'm building now is 1:66.

I believe if you use the Greenhill formula = 150 X diameter squared/length of the projectile.
(150 x (.45 X .45)/.45 for a roundball) = 1:67.5

If you use the modified Greenhill it is cal x 1.25 = .45 x 1.25 = 1:56

So toss a coin unless you plan on shooting conicals 

Getting old is better than the alternative, but your memory sure goes out the window.  That's the formula I was trying to find, but I couldn't remember the darn name of it so I could Google it.  Thanks for the information.

Mole Eyes

[Dphariss]

I'm about to order a .45 caliber barrel from FCI for an under hammer project I want to do this fall.  In all the guns of various calibers I've owned over the years I've never had a .45 caliber rifle.  The various makers use different twist rates for .45 caliber barrels (Colerain 1:48, Green Mtn. 1:60, Rice 1:66, etc.). 

This is going to be a barrel for round ball use and I need to specify the twist rate I want when I order the barrel.  Having no experience with the caliber I don't know what the optimum twist rate for a round ball barrel in .45 caliber should be.  Is there a generally accepted "standard" twist rate for this caliber?  Thanks.

Mole Eyes

Any RB twist with decent rifling form and depth, .008-.010" is deep enough will make all the velocity needed. A 50 cal will work fine with a 48 and will shoot fine with HV loads. So will a 66 or a 70.
If it were me I would use a 48 in a 45. Having a specific twist is just not that important with a RB.

Dan

[Dphariss]

Greenhill is irrelevant to the RB. It was meant for ARTILLERY.
Its only close for bullets... Its off about 10% in BPCRs for example where the twist IS important.

Dan

[JoeG]

A 1:48 twist was a pretty common twist in the old days
I have a .45 douglas barrel and a .50 Getz barrel both in 1:48
they both shoot better than I can hold

[moleeyes36]

I just got off the phone with Charlie Burton and ordered the barrel.  Charlie said his standard twists for a .45 are 1:57 and 1:66 and he prefers the 1:57 himself.  Based on his recommendation and the inputs I got here, I went with the 1:57 twist.  So in 6 to 8 months I'll have the barrel.  Thanks.

Mole Eyes

[flehto]

Just wondering if choosing any  twist between 1:48 to 1:66 really makes a difference in a .45. using a PRB?  My super accurate squirrel LR has a .45 Douglas bbl  X42"  lg  w/ a 1:66 twist and shoots a squirrel load of 30 grs 3f  which has gotten mostly head hits . For deer, the load is "upped" to 70 grs 3f and is also very accurate. By the way, I was fortunate that both loads which are suitable for squirrel and deer don't require a sight adjustment when changing from one load to the other.

Conicals are a different story and do require faster twists.

Perhaps the twist, w/in reason,  isn't that important when  shooting PRBs? ......Fred

[bob in the woods]

I had one of those Douglas .45 cal  1 in 66 in twist barrels.  It made up into a nice rifle that was extremely accurate.
Great barrels.

[eddillon]

Greenhill is irrelevant to the RB. It was meant for ARTILLERY.
Its only close for bullets... Its off about 10% in BPCRs for example where the twist IS important.

Dan

Dan,
Greenhill negates the length requirement.  Hence is valid for round balls.  The specific gravity for lead is slightly greater that the specific gravity of a jacketed bullet so the calculation has a slight error.



I used the QuickLOAD software to calculate the twist.