Twist rate for .357

[Matt15]

I am thinking of building a .357 disco with a cothran valve. What I need to know is what would be the best twist rate for bullets between 120 and 130 grain at 850-900 fps? This would be a bullet shooter for coyotes.

Thanks

[nielsenammo]

1:26 is,available from TJ and would work great

[Matt15]

1:26 is,available from TJ and would work great

Thanks! I was planning on using that barrel but thought I would double check.

[TroyHammer]

1-26" seems a little slow for that heavy of a bullet. A 9mm handgun/rifle uses 1-16" and shoots 115 gr. Mine is a cothran valve disco build with 1-16" twist 28" barrel.

[Matt15]

Airguns use a slower twist rate than firearms.

[nielsenammo]

1-26" seems a little slow for that heavy of a bullet. A 9mm handgun/rifle uses 1-16" and shoots 115 gr. Mine is a cothran valve disco build with 1-16" twist 28" barrel.

1:26 is a proven twist rate.  Used in Slayer and RAW airguns.  What slugs are you shooting out to 100 yards with success?  Not pellets but slugs/bullets.

Also the math is the math when it comes to twist rate, it is not a guess.  The math for that weight bullet is perfect with 1:26, a 1:16 barrel is suited for bullets roughly 180 grains.

[Extreme Big Bore]

I am no expert on twist rate but have seen some crazy things work on my .408 I went with a 1 in 32 twist rate and it shoots 160, 230, 270 grain great out to 100 yards. I think the TJ's 1 in 26 would be a great choice that is what I use for my .357 from what I have seen is for 100 yards and under a slower twist rate works great and allows for more bullet choices for hunting. For long range and long bullets I have found a fast twist works better the .308 long range rifles I built for my guys were a 1 in 8 twist rate that seemed to work much better at longer range. Seems to me short bullets want a slower twist rate kind of like old muzzle loaders they had a 1 and 66 twist rate for round balls but would not shoot longer bullet well.

[nielsenammo]

I am no expert on twist rate but have seen some crazy things work on my .408 I went with a 1 in 32 twist rate and it shoots 160, 230, 270 grain great out to 100 yards. I think the TJ's 1 in 26 would be a great choice that is what I use for my .357 from what I have seen is for 100 yards and under a slower twist rate works great and allows for more bullet choices for hunting. For long range and long bullets I have found a fast twist works better the .308 long range rifles I built for my guys were a 1 in 8 twist rate that seemed to work much better at longer range. Seems to me short bullets want a slower twist rate kind of like old muzzle loaders they had a 1 and 66 twist rate for round balls but would not shoot longer bullet well.

1:32 is a good choice for .408, probably better performance on the lighter bullets at distance would be my guess but I have never shot one of your rifles.  The math works out to be a faster twist rate for those bullets but if you are getting accuracy is shows slower is still stable but when you run the twist too fast the accuracy falls apart after 50 yards or so.  Seems like you got an handle on the twists.

[Extreme Big Bore]

With the .408 with a 1 in 14 twist I found the first shot would be at zero and the second would always be 1 1/2 high and 1 1/2 left on a 4500 PSI fill when I went to the slower twist I got two shots per fill at zero. Again not a expert at this twist thing just telling what I have seen. Had a long talk with Mike Sayers at TJ's today he explained why the math does not work when it comes to air rifles he claims it is do to the instantaneous blast that powder delivers and air rifles do not have the same effect on the bullet. The air is moving much slower and uses the barrel length to do the work. He also got into bore size and land grove dimensions that are very different for air rifles over traditional powder burners. This man seems to know the most about these issues that I know but he will never get on these web sites if there is any questions anyone wants answered post it on here and I will call him and tell you what he claims will work. I have listened to him and things work out pretty good for me.

[TroyHammer]

http://kwk.us/twist.html

I've found this useful. It helps determine the best twist rate for a specific bullet or what type of bullet should work best in your particular twist.

[K.O.]

to me it would seem unless it is a disco double or bottled disco going with  lighter rounds 95g-105g would be a better choice...

the specs on the TJ liner are .357 groove with .350 lands 6 L&G... so the 9mm luger/.380 molds should swag out and work fine... If they drop to small could lapp the mold...

?

[dyotat100]

That calculator is way off.

It's says that the 257420 74 gr at 950 fps needs a 1:12.

Not all of the calculators work for us or who says they even work.

So that would mean every 257 out there is wrong when people are shooting dime size groups with 85 and 92 gr in the same 1:14 twist barrel.

[dyotat100]

Here is one that is right or at least matches what we already know.

https://www.vcalc.com/wiki/AndrewBudd/Greenhill+Formula+for+Optimal+Rifling+Twist+Rate

[K.O.]

http://kwk.us/twist.html

I've found this useful. It helps determine the best twist rate for a specific bullet or what type of bullet should work best in your particular twist.

You might want to switch to this calc it include for subsonic I am betting the one you are using does not...

http://www.geoffrey-kolbe.com/barrel_twist.htm

the .357 lever guns  have a very wide range of twist,

Marlin 1:16       

Uberti  1:18  (I think)

Winchester 1:19 and 1:26    (94 trapper)

If I remember right Rossi is 1:30

and there was a  Browning   1:38 I think

[rsterne]

Most of the twist calculators are NOT intended for subsonic use.... Here is what the Kolbe Twist Calculator says for Stability Factor for a Lyman 257420 in a 14" twist....



As you can see, there is no problem, even right at Mach 1 with that bullet and twist combination.... but the stability is certainly dependant of the velocity.... A Stability Factor of 1.5 is considered optimal for maximizing the BC while not spinning the bullet too fast....

Bob

[Tofazfou]

You will find than tons of twist work.  1 quest is to match power plant to twist rate.  The bulldog shoots 145 gr nosler at about 775 fps +- some.  It has a 14" twist.  Thats just not appealing to see.  A gun with tha power plant would have been better suited to a 20" or 26" twist.

Nothing wrong with 20" and 26" twist for a 357 cal airgun shooting pellets, roundballs and midweight slugs

[nielsenammo]

In the testing I have done I have found that slower is more forgiving. 

[MJP]

Sometimes faster works, for what ever reason. I shoot with the Evanix 357 barrel in my af style frame and I think it's 16" twist if remembering correct. It shoots good with 82-200gr bullets up to 300m mostly I use 142-156gr it's really accurate with those. Beer cans consistently at 300m accuracy. But speed needs to be 300m/s and above.

Marko

[Hobbyman2007]

I'm using a 1:16 barrel liner in my .357. It shoots the .358 swc and JsB pellets very well out to 100 yards and more . The gun is at 150 fpe  give or take .