illinoisburt
Member
Part of the mystery of finding an accurate load for your particular rifle is knowing the twist rate. As a general rule, the more bearing surface the faster the rifling needed to stabilize the bullet. Therefore it's helpful to know what twist a rifle barrel is cut when looking for suitable weight bullets
The industry has settled on standard twist rates which work well for a given caliber, but those numbers have changed some over the years as bullets became longer and more streamlined. Some cartridges changed in common usage to lighter or heavier bullets as well. So there may be a lot variance from one make and model rifle to another.
Web searches can turn up tons of information, but why not measure it yourself and know the answer definitively?
To start we need just a few common items: a cleaning rod with tight fitting patch or brush, masking tape, a pen, and a ruler.
Start with 2 pieces of tape on the rod. It works best to place the front piece a little back from the patch so you can have it well engaged in the rifling when we start the next steps. A second piece of tape should be placed at least a foot or more farther up the rod.
Make a line on both piece of tape so you can index at the start and track the revolution as the tod turns.
With the patch in the barrel, line up the edge of the tape with the end of the barrel (or any barrel attachment). Index the rod with the front sight, or mark an index point on another piece of tape on the barrel. The edge of the tape will be our beginning measurement point so take care when lining everything up.
Next, carefully push the patch or brush into the barrel, allowing the rod to turn as it moves forward. This may take a little finesse the first time or two.
Once the patch has moved far enough for the second tape line to have made 1 full turn and line up with our index, stop and mark the rod at the end of the barrel by wrapping a new piece of tape with the edge even with the crown or accessory edge.
Remove the rod from the barrel and measure from the leading edge of the front piece of tape to the leading edge of the marking tape. That distance is 1 full turn. In this case, that is 9 inches. So my rifle has a 1 in 9 inch twist rate.
You can easily run the same rod back through to verify your measurements.
The industry has settled on standard twist rates which work well for a given caliber, but those numbers have changed some over the years as bullets became longer and more streamlined. Some cartridges changed in common usage to lighter or heavier bullets as well. So there may be a lot variance from one make and model rifle to another.
Web searches can turn up tons of information, but why not measure it yourself and know the answer definitively?
To start we need just a few common items: a cleaning rod with tight fitting patch or brush, masking tape, a pen, and a ruler.
Start with 2 pieces of tape on the rod. It works best to place the front piece a little back from the patch so you can have it well engaged in the rifling when we start the next steps. A second piece of tape should be placed at least a foot or more farther up the rod.
Make a line on both piece of tape so you can index at the start and track the revolution as the tod turns.
With the patch in the barrel, line up the edge of the tape with the end of the barrel (or any barrel attachment). Index the rod with the front sight, or mark an index point on another piece of tape on the barrel. The edge of the tape will be our beginning measurement point so take care when lining everything up.
Next, carefully push the patch or brush into the barrel, allowing the rod to turn as it moves forward. This may take a little finesse the first time or two.
Once the patch has moved far enough for the second tape line to have made 1 full turn and line up with our index, stop and mark the rod at the end of the barrel by wrapping a new piece of tape with the edge even with the crown or accessory edge.
Remove the rod from the barrel and measure from the leading edge of the front piece of tape to the leading edge of the marking tape. That distance is 1 full turn. In this case, that is 9 inches. So my rifle has a 1 in 9 inch twist rate.
You can easily run the same rod back through to verify your measurements.
