Rates of twist

[Aussie Bruce]

Greetings all from down under,
Can anyone advise me of thr rate of twist of the rifling in the following revolvers:-
Model 14 Ser No K933702
Model 16 Ser No BEZ7872
Model 19 Ser No K903332
Pre Model 27 Ser No S84176
Model 27 Ser No S282870
Thanks in advance

 

[pistola]

1 in 18 3/4".

 

[garbler]

Greetings all from down under,
Can anyone advise me of thr rate of twist of the rifling in the following revolvers:-
Model 14 Ser No K933702
Model 16 Ser No BEZ7872
Model 19 Ser No K903332
Pre Model 27 Ser No S84176
Model 27 Ser No S282870
Thanks in advance

As I recall all S&W barrels are 14" twists and Colts are 16". The later being preferred for most target work.

 

[Alk8944]

As I recall all S&W barrels are 14" twists and Colts are 16". The later being preferred for most target work.

You recall incorrectly, they are all (revolvers) 18 3/4", just like pistola stated.

 

[garbler]

You recall incorrectly, they are all (revolvers) 18 3/4", just like pistola stated.

Well I will take your word for this but I need to ask you since I have been out of the business for a while and might not recall all the details. Anyway is the 18" twist something S&W started doing after Steve Melvin and the British took over or are you saying they were always an 18" twist ?

The reason I ask is back in the 70's when I was in gunsmithing school we had a two day armorers course set up by the S&W's people. I found my notes from that course and they said their barrels were a 14" twist . Then about tens years after that class I was enrolled in another gunsmithing school in NC and a big part of the class was fitting up competition revolver barrels and of course setting back S&W barrels. Again my notes and I recall the instructor telling us S&W used a 14" twist and Colt a 16". So then I started pulling a bunch of old invoices from years ago for custom barrels I bought from Power, Wichita, Barnett, Douglas and Nowlin and all the 38-357 barrels were a 14" twist but some of the 44-45 cal were 16".

So I am a bit confused on this since I was taught by some pretty heavy hitters in the revolver world that at least the earlier S&W's were a 14" twist.

addendum Edit : Went out and dug up some old reference sources and talked with a smith I know in Canada and I don't see where an 18" almost 19" twist is going to do much at all for the medium calibers such as 32-41. It seems to be too slow for these smaller bullets. I can see this slower twist being a distinct advantage with some of the larger bullets being shot in 44-45 caliber guns however. I would be interested in your thoughts on this

Regards

 

[GBertolet]

The S&W twist rate for the 38/357 revolvers is 1 in 18 3/4 inches. It has been for a long time. The standard 44 cal is 1 in 20 inches, and I believe the 45ACP revolver is 1 in 16 inches, just like the 1911 Colt auto.. Someone correct me if I am wrong on the 45ACP. Many Colt 38/357 twists are 1 in 14 inches. Many aftermarket barrels for this caliber are this twist rate also, as many feel the faster twist stabilizes low velocity wadcutter bullets better than the slower S&W 1 in 18 3/4 twist.

 

[Texas Star]

I think Garbler is confusing custom barrel twists with std. factory twists.

Colt is 1:14" and S&W at 1:18.75". Ruger is at S&W level for DA's; I tihink some of their SA .357s were about 1:16".

I have an old Speer manual that lists twists for many companies, inc. rifle barrels and recall many from various articles and books.

I have seen bullet expansion tests, which usually show Colt-fired bullets expanding more than S&W-fired bullets. Velocities were similar, so I think that a faster twist helps to expand bullets.

I ran this idea past a very famous outdoor magazine gun editor who is more technically oriented than most of his peers. I posited that one reason why the 7X57mm is so effective with the usual faster Euro twist rate might be that the bullet spins pretty fast.

He replied that bullet rotation stops before the bullet is through the hide of, say, a deer, so it wasn't relevant. But I keep thinking of how .38 bullets from a Detective Special expanded better in some trials than they did from a four-inch M-10! Or, certainly, on par.

I asked the NRA, but the answer was so vague that I think it really meant that whoever responded didn't really know.

This field needs more exploration. If you fire bullets from a Euro 9mm, you'll probably see more expansion than if you shoot that same bullet from a S&W with a slower twist. This is ONE reason why I've never liked S&W autos.

 

[garbler]

I think Garbler is confusing custom barrel twists with std. factory twists.

Colt is 1:14" and S&W at 1:18.75". Ruger is at S&W level for DA's; I tihink some of their SA .357s were about 1:16".

I have an old Speer manual that lists twists for many companies, inc. rifle barrels and recall many from various articles and books.

I have seen bullet expansion tests, which usually show Colt-fired bullets expanding more than S&W-fired bullets. Velocities were similar, so I think that a faster twist helps to expand bullets.

I ran this idea past a very famous outdoor magazine gun editor who is more technically oriented than most of his peers. I posited that one reason why the 7X57mm is so effective with the usual faster Euro twist rate might be that the bullet spins pretty fast.

He replied that bullet rotation stops before the bullet is through the hide of, say, a deer, so it wasn't relevant. But I keep thinking of how .38 bullets from a Detective Special expanded better in some trials than they did from a four-inch M-10! Or, certainly, on par.

I asked the NRA, but the answer was so vague that I think it really meant that whoever responded didn't really know.

This field needs more exploration. If you fire bullets from a Euro 9mm, you'll probably see more expansion than if you shoot that same bullet from a S&W with a slower twist. This is ONE reason why I've never liked S&W autos.

Okay you guys win and I was mistaken. So it looks like I must of been recalling the optimal twist with custom barrels I fitted up for pin, plate and PPC guns I built years ago. Though S&W apparently used the slow twist the faster 14-16" twist will generally give you better accuracy with 32-38 cal. When you jump to 44-45 then the slower twist pays off with the longer heavier bullets but not semi-wadcutter types. Like I said originally I was going from memory and it ain't what it used to be so my old notes talking about 14" twists and S&W revolvers were really misinterpreted and were actually saying this was optimal on 38-357 guns and NOT factory stock.

As for the theory that a faster spin mean more expansion well there are way too many factors to really say given bullet design, distance, velocity, etc. etc. .

As for the 7x57 Mauser being such a good game killer due to twist well this is something I never heard before credibly. It was always my understanding that the cartridge was often loaded with bullets of very high sectional density ( up into the 300’s ) often 190 grains and larger. These bullets were unusually long for their diameter so a slower twist is normally needed to stabilize them. Also many of these older Mauser actions were throated pretty deep so these long narrow bullets could be seated way out. Fact is this cartridge with these long bullets defied those writers that told us to keep the bullet in the neck and not into the shoulder/powder column. Guys like Karmojo Bell killed a lot of elephants with this cartridge but it was more about his finding that sweet spot through the brain pan. Other African hunters of the past like Corbett shot and like the cartridge for a wide range of plains animals and even lions as I recall. But Finn Aagaard was last writer I knew of who really promoted this old veteran round as a reliable killer without a lot of flame and smack.

 

[Skeetr57]

Garbler, you have it exactly backwards. The longer the bullet for a given diameter, the faster the twist rate to stabilize it. The first .30 caliber us military was the .30-40 Krag with a 220 grain bullet, and the best twist rate was determined to be 1 turn in 10 inches. This was carried over to the .30-06 as its original bullet was also 220 grains. Later .30-06 ammo was loaded with either 150 gr or 172 gr bullets, without changing the twist rate. The M14 was designed around the 7.62x51 NATO round with a 150 gr bullet, and the rate was reduced to 1:12.