rifling twist on lyman great plains rifle

[bluecarpenter]

Was wondering what the rifleing twist is on my greatplains rifle. Have had it for a year and can't remember. Thanks.

 

[paulvallandigham]

It should be 1:66, but you need to measure it yourself to be sure.

 

[bluecarpenter]

How do I measure it.

 

[DEWB]

Twist on a lymam round ball barrel is 1 in 60"

 

[bluecarpenter]

Nothing on barrel that says rate of twist just says great plains And some other marks

 

[longcruise]

The twist on the current production rifles is 1:60. Originally they were 1:66 but the rate changed sometime between 1985 and about 1996. All dates approximate. My rifle which dates to about 1981 has a 1:66.

I'm not sure why they changed it, but it probably had something to do with production needs in the factory.

 

[Zonie]

How do I measure it.

You will need a cleaning rod, a cleaning jag and a lightly oiled patch.

A piece of masking tape and a pen plus a ruler or tape measure is also needed.

Fit the jag on the rod and put the patch on the jag.

Run it down the barrel until it stops on the breech plug.

Wrap the masking tape around the rod so that it is flush with the muzzle.

Mark a line on the tape in line with the front sight.

Slowly retract the rod allowing it to rotate at its own rate.
Keep on retracting the rod until the mark on the tape has rotated 1/4 of a full turn from where it started.

Measure the distance from the muzzle to the lower edge of the tape.

Multiply this distance by 4 and you will have the rate of twist.

For instance, lets say the rod moved 12 inches to rotate the mark from the 12:00 o'clock position to the 3 o'clock position (1/4 turn).

Multiplying 12 times 4 you get 48, so the rate of twist is 1:48.

Repeat this whole thing several times because if the patch "jumps" a groove because you were unknowingly preventing its free rotation the reading will be wrong.

After several trys you should have a feel for this and you will get a good answer.

 

[paulvallandigham]

Go back to the Index page for this forum. Up towards the top you will find an entry, " Articles, Charts, and Links". Click on articles. Claude has posted an article written by one of our members that explains how to measure the ROT in your rifle that makes it easy to do. :thumbsup: