Swiss Arms Twist Rates

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saskcop

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I know that there are many SAN gurus on here.

I have been shopping for a SAN, but I am trying to figure out which ones have 1 in 7" twists. Except for being able to put a cleaning rod down the pipe and figuring out the twist, is there any other way to find out the rate of twist in these rifles? I have been told that it is not stamped on the guns. Are the flat tops all 1 in 7" or are some of them 1 in 10"?
 
Savage said:
Commercial 1-9" unless you replaced your barrel with a SIG military barrel then 1-7
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Swiss arms barrels, either civilian or the Stwg 90, are 1 in 10. The 1 in 7 is special order.

I had both before, they are not marked in any obvious manner.

I had shot 69 SMK and SS109 out of 1-10 swiss arms many years ago. Sierra bullet box clearly shows that 69gr SMK needs 1-10 and faster. SS109 basically has the same length as 69gr smk but lighter. There is no point of chasing 1-7 unless the rifle needs to shoot 77gr/75gr bullets.
 
greentips said:
Swiss arms barrels, either civilian or the Stwg 90, are 1 in 10. The 1 in 7 is special order.

I had both before, they are not marked in any obvious manner.

I had shot 69 SMK and SS109 out of 1-10 swiss arms many years ago. Sierra bullet box clearly shows that 69gr SMK needs 1-10 and faster. SS109 basically has the same length as 69gr smk but lighter. There is no point of chasing 1-7 unless the rifle needs to shoot 77gr/75gr bullets.
Click to expand...

Thanks for setting the record straight
 
greentips said:
Swiss arms barrels, either civilian or the Stwg 90, are 1 in 10. The 1 in 7 is special order.

I had both before, they are not marked in any obvious manner.

I had shot 69 SMK and SS109 out of 1-10 swiss arms many years ago. Sierra bullet box clearly shows that 69gr SMK needs 1-10 and faster. SS109 basically has the same length as 69gr smk but lighter. There is no point of chasing 1-7 unless the rifle needs to shoot 77gr/75gr bullets.
Click to expand...

That is just it. I love loading the 75-77 grainers and have had super luck with them. That being said, I have also had some 69 grain Nosler Match loads that would shoot tiny little groups.
 
greentips said:
Swiss arms barrels, either civilian or the Stwg 90, are 1 in 10. The 1 in 7 is special order.

I had both before, they are not marked in any obvious manner.

I had shot 69 SMK and SS109 out of 1-10 swiss arms many years ago. Sierra bullet box clearly shows that 69gr SMK needs 1-10 and faster. SS109 basically has the same length as 69gr smk but lighter. There is no point of chasing 1-7 unless the rifle needs to shoot 77gr/75gr bullets.
Click to expand...

Or tracers because that's the only reason military users go to the 1-7 barrel. But it will allow you to shoot the Mk262 from Black Hills.
 
The primary reason the Swiss military adopted 1-10" was for increased barrel life and given that the GP90 round is stable with it, it saves barrel changs.
 
I had some leftover Hornady BTHP 75, so I decided to shoot them through my 1/10 Swiss. It seriously looked like a shotgun had hit the paper.

So I guess one way to tell is to just shoot a group of heavy projectiles ;)
 
Putting obsession with terminal ballistics and shooting things with 5.56 at 700 yards aside, 69gr SMK is a better round for general shooting because it's velocity and bullet shape are closer to SS109.

This means 69gr SMK drop table tracks closely to all the military BDCs designed for SS109 out of M4 carbine, like ACOG and Elcan Spectre DR.
 
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