Rifle twist confusion question

[kelljp]

On my stock Thompson Center barrels I know if my ramrod rotates one half turn in 2 feet it is a 1:48. But I'm getting confused on some other barrels (30-32 inch) long.
What's the rotation in 2 feet of the ramrod for a 1:60 or 66 twist ? Thanks for any input, I keep coming up with different rates. Old age sucks

 

[bubba.50]

24in=2 feet 60in=5 feet 2 feet is 40% of 5 feet so, looks to me like it would be roughly 2/5ths of a turn.

 

[ohio ramrod]

This is a good application of the old slide rules.Just set up the proportion 1:48 and read off the corresponding points for different twists. Oh I forgo,t you young wippersnapers don't even know what a slide rule is, much less, how to use one.

 

[SciAggie]

Ahem….

 

[kelljp]

This is a good application of the old slide rules.Just set up the proportion 1:48 and read off the corresponding points for different twists. Oh I forgo,t you young wippersnapers don't even know what a slide rule is, much less, how to use

I told my wife not to throw that box of stuff from college in the attic away. I knew I'd need that slide rule again eventually

 

[Nameless Hunter]

On my stock Thompson Center barrels I know if my ramrod rotates one half turn in 2 feet it is a 1:48. But I'm getting confused on some other barrels (30-32 inch) long.
What's the rotation in 2 feet of the ramrod for a 1:60 or 66 twist ? Thanks for any input, I keep coming up with different rates. Old age sucks

A 1:60 rifle twist produces 1/2 ramrod rotation in 30inches (2-1/2 feet) of ramrod travel.
Rotation for just two feet of ramrod travel gets a little tricky to measure since you're not going to get a full half twist (180 degrees) of the ramrod.
Instead, you'll get a rotation based on 48 (twist) divided by 60 (twist), which is 0.8 (80 percent) of 180 degrees.
So, .8 x 180 degrees = 144 degrees of ramrod rotation with two feet of ramrod travel in a 1:60 twist barrel - real hard to measure.
If the 1:60 twist barrel is less than 30" long, you're probably better off trying for 15" of ramrod travel - for a 1/4 rotation of the ramrod.
Hope that's clear as mud...

 

[kelljp]

Thanks

 

[Grenadier1758]

Instead of a half turn, .measure a quarter turn. It's relatively easy to see a quarter turn on an octagon barrel. Measure how far you have pulled the rod to get the quarter turn and multiply by four. Do the measurements 5 times with a fresh patch on the jag. I don't trust that brush won't get stuck, then we'll have another thread to make comments.