Fast twist barrels

[Hiwall55]

I recently saw a 40/70SS with a 1 in 12 twist barrel for sale and I was wondering if anyone else had any experience with such a fast twist and how it shot. Thanks

[Chill Wills]

Highwall55,
If it is a 12 twist and not a typo I do not think I could invest in it.


I have 40’s in 16 twist, 14.5 twist and 13 twist. The 13” twist is a 40-70 SS. It is the only 40cal I have not been able to make shoot reliably.
And it is a Highwall too.:drinks:

I have no idea if it is the fast twist that is the trouble or the chambering ……or maybe something else about the rifle that is the problem but the outcome is the same. It makes Great groups and then it misbehaves for a few shots and then back to putting the shots where they should go. I have looked at everything else I (we) can think of. If I was rolling in dough $$$ I would re-barrel it in a 16 of 14.5” with the same reamer and see what that does.

[drcook]

a 1:12 does seem a might fast. I have a 40-82 in a 1:13 twist Lilja barrel and am going to start working with it for load development. I have the 1:13 for longer bullets.

Chill Wills, what cartridge are you shooting ? A rifle that groups then has some fliers then has good groups sounds like it could be an annealing problem. Try annealing your brass and see if that helps.

[waksupi]

Lube purging is another possibility.

Thinking along, It may just need a heavier boolit.

[Chill Wills]

a 1:12 does seem a might fast. I have a 40-82 in a 1:13 twist Lilja barrel and am going to start working with it for load development. I have the 1:13 for longer bullets.

Chill Wills, what cartridge are you shooting ? A rifle that groups then has some fliers then has good groups sounds like it could be an annealing problem. Try annealing your brass and see if that helps.

drcook,
" The 13” twist is a 40-70 SS. It is the only 40cal I have not been able to make shoot reliably. "

yes, you might be on to something but we have ruled that out so far. It would be easy to try and is on the list. It is a Lilja as well chambered to 40-70 SS.

waksupi, Tom Gray's theory of lube purge is a tough one to prove. Especial if the barrel gets wiped between shots. With smokeless-maybe. With BP, ...not so much a chance and not see it with other BPCR loads and rifles.
In fact, don't even say that! You'll keep me awake at night thinking about it!:kidding:

Michael Rix
Lots to try, lots to try....

[drcook]

Sorry, my post was addressed to 2 different folks. I caught on that your rifle was a 1:13.

The 1:12 was addressed to hiwall55.

Mine is chambered in 40-82 Crossno. After I finish the wood and start shooting it again in the spring, I might even drop down to 1F and see how that shoots in it.

[Hiwall55]

This one is a SHILOH 40/70SS with a 490 gr. Brooks creedmore w/ 1 in 12 Twist. My .40's all have 1 in 16 and I was wanting to build one in 1 in 14 twist , but I found this and I haven't heard of such a fast twist. any way thanks for the Info, I think I will pass on it.

[drcook]

Was it is that Shiloh out on gunbroker that was rebarreled? If so, it also has a 1:16 45-100 barrel that goes with it. If that barrel is long and heavy enough, that could make a good long distance blaster

[Boz330]

One of the guys I shoot with has a 12 twist 40cal. He hasn't had a lot of luck with it, but then he doesn't have a lot of luck with anything.

Bob

[Hiwall55]

drcook, yes that is the one,I am looking to buy or build a 40/70SS but that twist in that barrel seems like it might not be for me

[Bad Ass Wallace]

I'm building another 40/65 at present with a Badger 1:16" twist. The metal work is finihed just waiting on a new stock. I had a chance to test fire it with the 420gn Snover and it was brilliant.

I have a "fast twist" 1:12 Pedersoli Hiwall 38/55 and when loaded with a Paul Jones 374gn boolit it will just shoot exceptionally well.

I have dies and cases for a 40/90 Sharps BN and have been thinking about a 1:14" barrel for this project. What weight boolit would this shoot; perhaps 450gns.

One thing that the 38/55 has shown is that a heavy boolit in front of the main powder charge, not only builds up a back pressure that seems to make the powder burn hotter and cleaner, but the velocity per grain of powder is very high.

So in a 40/90 which has a reputation for not being a very accurate chambering, a heavy boolit in a fast twist barrel may just be the combination that will work:roll:

[Texantothecore]

From Titan Reloading:

Greenhill formula
T=150 x D
_____
R

T is the twist required (number of inches for one revolution),
D is the bullet diameter (in inches)
R is the bullet length to diameter ratio, (length divided by diameter)

Conversely, to find out what length bullet will be stabilized in a given twist, use:




L=150 x D x D
___________
T (that is, 150 x D squared divided by T)

L is the bullet length
The number 150 is a constant used by Greenhill and works well at velocities in the vicinity of 1500 f.p.s. or greater. At 2800 f.p.s. the constant can be changed to 180 with good results.

Note that it is bullet LENGTH, not weight that is important. Greenhill works well with all lead/lead-alloys commonly used for bullets.

the above was written by Normal F. Johnson, at the following address; http://www.recguns.com/VIIIB6.html

Minimum twist is one of the many calculators included in the Lee Shooter Program.